Establishment of a Quality Assurance System for Minimally Processed Jackfruit
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Establishment of a Quality Assurance System for
Minimally Processed Jackfruit
Mohd. Salleh Punan, Abd. Shukor Abd. Rahman, Latifah Mohd. Nor, Pauziah
Muda, Ahmad Tarmizi Sapii, Rohani Md. Yon and Faridah Mohd. Som*
Abstract
Jackfruit (Artocarpus heterophyllus) of Malaysia is commonly consumed as fresh produce and hence is sold
as whole fruit, sections/quarters and minimally processed (MP) products. The demand for retailing the fruit as
MP products is expanding due to the recent trend of consumers towards ready-to-eat and quality produce. Both
domestic and export markets prefer MP jackfruit in their retail outlets, especially at supermarkets,
hypermarkets and fast food centres. Hence, there is a need to develop a proper minimal processing technique
for the preparation of MP jackfruit. The operation involves harvesting at the right level of maturity, correct in-
field handling, sorting, washing, ripening, cutting and removal of the core, taking and selecting individual
fruitlets, packing, storage and transportation. These operations should be monitored consistently to ensure the
quality and safety of end products. A quality assurance (QA) system has been established and implemented for
the processing and management of the product from the point of harvest, postharvest operations and minimal
processing, up to the retailing of the end products. The components in the QA system include control of raw
materials, postharvest operations, sanitation at the processing plant, minimal processing unit operation and
control of end products.
JACKFRUIT (Artocarpus heterophyllus) is one of the and difficult-to-peel fruit, reduced costs in packaging
non-seasonal fruit crops grown widely in Malaysia. and transportation, more convenience, maintained
Depending on the type or clone, the fruit is consumed freshness, extended shelf life and minimised quar-
fresh, or as canned slices, fruit juice and dried chips. antine barriers in some importing countries (Reyes
For fresh consumption, the fruit is commonly sold as 1997a).
whole fruit, sections/quarters and minimally Product quality is one of the prime factors in
processed (MP) produce. Recently, the demand for ensuring consistent marketing of MP jackfruit. It is
marketing jackfruit as MP product has been expanding well known that quality is a combination of various
due to the recent trend of consumers towards ready-to- parameters demanded by consumers such as colour,
eat and quality fresh produce. The demand is appearance, shape, size, texture and taste. However,
expanding not only within the traditional market there is no precise measurement or standard unit to
outlets, but also in other market sectors such as food identify product quality objectively, since it is always
services, fast food outlets and food processors associated with the degree of acceptance by the
(Vinning 1995). The trend is similar in other Associ- consumer (Kramer and Twigg 1970). A quality
ation of South-East Asian Nations (ASEAN) countries assurance (QA) system was proposed for the horticul-
including Singapore and Brunei, where most of their tural industry by the Natural Resources Institute
produce comes from Malaysia. The reason for this (1994) to monitor the quality of fresh produce
trend is understandable, as MP produce offers some according to consumers’ demands. The ‘assurance’ in
advantages, such as ease in serving portions of large QA has been defined as “consistently and reliably
delivering products and services that have been prede-
* Malaysian Agricultural Research and Development termined by the markets” (Piccone and Bunt 1997).
Institute (MARDI) Headquarters, PO Box 12301, 50774
Kuala Lumpur, Malaysia.
115
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)The QA concept is also essential in minimal Harvesting is done by cutting the stalk using a sharp
processing of jackfruit to control variability in pro- knife and holding the fruit to avoid it dropping.
duction and end-product quality due to differences in
growing techniques, seasonal effects, a range of post- HARVESTING Farm quality assurance
harvest conditions, variation in processing techniques Preharvest treatment
and facilities, human factors and market conditions. Maturity index
This paper elaborates the quality system developed for Harvesting method
IN-FIELD HANDLING Fruit specification
implementation during preparation and distribution of
MP jackfruit for both local and export markets. The
components of the QA system include control of raw PACKAGINGHOUSE OPERATIONS
materials, postharvest operations, sanitation at the
• Receiving
processing plant, minimal processing unit operation • Quality inspection
and control of end products. • Sorting
• Washing & rinsing
RIPENING
Minimal Processing Procedures
Minimal processing of produce results in the breaking
MINIMAL PROCESSING
of plant cells and liberating oxidising enzymes. The
surface of the cut produce is exposed to the sur- • Cutting & removal of the core
rounding air, thus enhancing contamination by • Taking individual fruitlets
• Sorting
bacteria, yeast and moulds. The main factors limiting • Quality inspection
the shelf life of MP produce are enzymatic browning,
white surface discoloration, microbial spoilage, senes- PACKAGING
cence due to increase respiration and ethylene pro- • Retail/small packs
duction, and degradation in nutritional value, texture • Bulk packaging
and flavour (Reyes 1997b). Hence, it is important to
STORAGE
ensure that all steps in the process are properly carried
out to minimise physical injuries, avoid contamination • Pre-cooling
• Low temperature
and maintain high quality of end products. An appro-
• Modified atmosphere/
priate procedure for the preparation of MP jackfruit controlled atmoshere
was established for commercial operations. The
TRANSPORTATION
procedure involves various steps of the operation from
harvesting up to market delivery (Figure 1). • Land transport
• Air freight
RETAILING
Harvesting
• Retail temperature/conditions
• Optimum shelf life
Jackfruit should be harvested at the right stage of • Quality inspection
maturity. The maturity indices used for whole, fresh
fruit can be used for choosing the correct harvesting Figure 1. Minimal processing unit operations.
stage of raw fruit for minimal processing. A maturity
study conducted at the Federal Land Development
Authority’s (FELDA) farm verified that the fruit is
fully matured after 14 weeks (100 days) from bagging, In-field handling
which is equivalent to 16 weeks from anthesis. At this
stage, the ripened fruit has good eating quality in terms Harvested fruit should be packed in bulk containers
of aroma, texture, sweetness and taste—the total made of either plastic or wood and delivered to the MP
soluble solids (TSS) content has reached about plant by lorry or pick-up van.
24°Brix, total sugar about 11–15%, while the total
titratable acidity (TTA) is about 0.3%. It is recom-
mended that fruit be harvested in the morning, as field
heat is still low and tolerable to the produce.
116
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Packinghouse operations Packaging
Fruit received from farms should be inspected to Minimally processed products should be packed
ensure that the quantity (weight) and the quality meet properly using a suitable packing material and system.
the required specifications. The fruit should then Packaging aims to protect the product from physical
undergo some minimum postharvest operations prior and microbiological hazards since their natural
to minimal processing to ensure maintenance of high protector (the fruit skin) has been removed. The
quality raw materials for processing. The minimum common packaging methods for MP jackfruit include
packinghouse operations include sorting, washing and polyethylene bags, polystyrene trays wrapped with
rinsing. Washing of produce should be done using polyvinyl chloride (PVC) film and polypropylene con-
chlorinated water to remove dirt, foreign matter, latex tainers with lids. Sealing packages may also involve
stains and any field contamination. After washing, altering the concentration of respiratory gases inside
produce must be rinsed properly to remove excess the package to create a modified atmosphere system.
moisture from the surface of the fruit. Modified atmosphere packaging has also been found
to be capable of preserving freshness and extending
the shelf life of MP products such as pineapple,
Ripening pomelo, durian and jackfruit (Anon. 1997).
Prior to the minimal processing, fruit should be Storage
ripened fully to achieve optimum aroma, sweetness,
taste and eating quality. Fruit should be kept at After packaging, MP jackfruit should be kept at a
ambient temperature to allow natural ripening within chilled temperature for storage before distribution. A
3–4 days. However, uneven ripening is a major storage temperature of 2°C was found to be suitable
problem in the natural ripening process, especially for for extending the shelf life of MP jackfruit for 3 weeks
large-sized fruit. An induced ripening method is rec- (Anon. 1997).
ommended for jackfruit to achieve more uniform
ripening of the fruit. Induced ripening is done by Transportation
keeping the fruit in a static or closed ripening chamber,
equipped with an ethylene gas tank and a flow rate MP jackfruit should be distributed using a refrig-
controller. Ethylene gas with a concentration of 50 erated lorry or pick-up van. It is important to maintain
parts per million (ppm) is flushed into the chamber set the chilled temperature of 2°C throughout the distri-
at 25°C. After 24 hours, the chamber is opened to bution process to avoid deterioration. It is
allow continuation of the ripening process under recommended that pre-cooled MP jackfruit be kept in
ambient conditions. The fruit ripens 3–4 days after the thermal-freeze box to maintain the chilled temperature
treatment with ethylene gas. along the journey to retail outlets. For the export market,
air transportation is recommended to ensure fast
delivery. Transportation by refrigerated sea-freight may
Minimal processing operation also be viable if the volume of the consignment is large
enough and the shelf life of the product is long enough
Fruit ready for minimal processing should be shifted to fulfil the total shipping and distribution periods.
to a hygienic processing room to avoid microbial con-
tamination of the cut surface. Basic operations may
include cutting the skin using a clean knife to remove Retailing
the core, taking individual fruitlets and sorting the
Most of the retail outlets for MP products are super-
fruitlets according to the required size, maturity and
markets, hypermarkets, the fast food sector, food
colour. Only full fruitlets (not half or partly cut) are
service sectors and food processors. It is once again
recommended for retailing. However, fruitlets with or
important to maintain the chilled temperature of the
without seeds can be prepared according to the con-
product at all outlet sectors to avoid deterioration. The
sumers’ preference. Multiple handling of the fruitlets
product may be stored temporarily for a period of not
should be minimised during minimal processing to
more than the expected shelf life. All display racks or
avoid injuries and contamination.
shelves in the supermarket or hypermarket should also
be equipped with refrigeration facilities.
117
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)QA System in Minimal Processing inspection of raw fruit at the processing plant. Both
processor and producer should agree on the tolerance
The QA system was established as a management tool limits of product quality to be delivered into the
to support the minimal processing operation for jack- processing plant.
fruit. The components in the QA system include
control of raw materials, sanitation of processing Raw material inspections
plants, control of processing operations and control of A system of inspection of all raw fruit entering the
end products. plant should be in place at all times. Inspection facil-
ities such as calipers, balances and thermometers
Control of raw materials should be provided and used by trained staff. A
standard quality form must be prepared and details
Raw fruit specifications recorded on it by the inspector. The details of the
Fruit brought from farms into the minimal record include date and time of receipt and inspection,
processing plant should comply with the specifica- name of supplier, vehicle number, produce temper-
tions agreed on by the grower/supplier and processor. ature on receipt, and condition or quality of produce
The specifications shown in Table 1 have been according to the specifications. A decision of either to
developed based on the Malaysian Standard of Speci- accept or reject the consignment must be made based
fication for Fresh Jackfruit (SIRIM 1986). The on the inspection analysis.
specification can be used as guidelines for quality
Table 1. Specifications of fresh jackfruit for minimal processing.
Parameter Specification
Variety Yellow or orange-coloured flesh
Pest and disease farm control 1. Control of stem borer by pruning the infested plant
parts, filling or injecting with methamidophos (tama-
ron), monocrotophos (azodrin) or dimethode (rogor)
2. Control of fruit borer and fruit fly by bagging the fruit,
removing rotten fruit and spraying with insecticide
3. Control of fruit rot by spraying with fungicide
Preharvest practice Bagging the selected fruit 2 weeks after fruit set
Maturity 100 days (14 weeks) from bagging
Harvesting method Manually with sharp knife
In-field packaging Fruit shall be packed in plastic containers, wooden crates
or similar protective containers
Labelling Each container shall be marked with the following
information:
• Name of produce/variety
• Net weight in kilograms
• Date of harvest/packing
• Name and address of producer/supplier
Quality requirements Fruit shall be of similar varietal characteristics, fairly well
formed, mature, not over-ripe, reasonable clean or free
from stains, dirt and foreign materials, and reasonably free
from injury, decay, disease, living and dead insects,
moulds and other contaminants
Size classification Fruit shall be classified according to size:
• Large, weighing 16 kg and above
• Medium, weighing 8 kg to less than 16 kg
118
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Sanitation in the processing plant Control of processing operations
Plant cleanliness and hygiene Production history
Sanitation in the plant involves consideration of
Although production activities at the farm level do
layout design, maintenance of walls, ceilings, floors,
not directly influence the minimal processing opera-
doors, plumbing, water supply, refrigeration system,
tions, relevant information should be made available
ventilation, glove/boot locker and toilet facilities
to the processor. This is important to the overall QA
(Cantwell 1996). The layout for a minimal processing
system so that corrective actions can be taken to
plant can be divided into four main areas: packing-
improve the industry. Some of the information to be
house area, minimal processing area, cold room
recorded includes source of fruit, grower’s code or
facilities and management office. The overall clean-
name, cultural practices, pest and disease man-
liness of the plant should be maintained since it is
agement, and preharvest practices.
considered to be food processing plant. Non-splin-
tering and easily cleaned surface materials should be
used for work surfaces, walls and floors. Regular Work instructions
washing and cleaning works should be implemented Workers and staff involved in the processing plant
using suitable chemicals and cleaning detergents. should be given clear and easy-to-understand instruc-
The area in which it is most important to be tions in order to carry out their duties properly. The
hygienic—and thus should be monitored most closely— content of the instructions should explain the precise
is the minimal processing area, where cutting of fruit, work to be done at every processing step. Work
sorting and packing fruitlets are performed. The room instructions should be made available to the workers
should be isolated from other areas to avoid contami- either in the form of a manual or display charts.
nation. The room should be provided with a double-door
access system to ensure maximum protection from HACCP
insects and microorganisms. Surfaces for the walls, floor
The Hazard Analysis and Critical Control Points
and ceiling of the room should be made from easy-to-
(HACCP) standard is well known in the food
clean materials. Washing, cleaning and sanitising should
processing industry as a system of monitoring and
be scheduled regularly before, during and after
controlling quality of processes and product, so that
processing activities. The room should be air-condi-
product is not contaminated with microbiological,
tioned to control room temperature at about 15–20°C, so
chemical or physical hazards. The system has been
as to maintain freshness of produce during processing.
recommended for implementation in the minimal
Equipment processing of fruits and vegetables (Cantwell 1996;
Reyes 1997c). For MP jackfruit, a HACCP worksheet
All appliances and facilities including knives,
has been established to monitor minimal processing
scissors, secateurs, containers and the cutting bench
operations right from receiving the raw fruit up to the
must be made from rust-proof materials, such as
distribution to retail outlets (Table 2). The guideline
stainless steel or plastic. Equipment and appliances
was verified commercially at the Federal Land Devel-
used in the processing works should be cleaned and
opment Authority’s minimal processing plant.
sanitised. Basic steps for sanitation involve physical
cleaning, pre-rinsing, detergent application, post-
rinsing and sanitation using either steam, hot water, Control of end products
chemical detergent or chlorinated water.
End-product specifications
Staff and workers
Staff and workers preparing and handling MP The processor/producer and distributor/retailer for
jackfruit have a great responsibility to ensure the each specific market should clearly define end-product
health and safety of the end users. It is important to specifications. For MP jackfruit, the specifications
ensure that all staff and workers entering the plant— shown in Table 3 are proposed as guidelines for
especially the processing area—wear clean apparel, quality inspection. Both the processor/producer and
gloves, caps and boots. Changing rooms and lockers distributor/retailer should agree on the tolerance limits
for personal belongings should also be allocated to of end-product quality to be delivered into the market.
each worker.
119
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Table 2. Hazard Analysis and Critical Control Points (HACCP) worksheet for minimal processing of jackfruit.
Operation Potential hazard(s) Control measures CCP Critical limit Tolerance Monitoring proce- Corrective action
(Yes/No) dure
Receiving raw Fruit borers, fruit fly and Ensure in-field bagging and Yes Infected area 10% area defects Inspection of Wash with
fruits fruit rot discard infected fruit softened infected fruit fungicide
Blemishes, immature Discard blemished, immature No Soft fruit, unripe Flesh too soft Inspection of the Proper in-field
and overripe fruit and overripe fruit fruit flesh handling
Washing and Contamination due to Ensure water quality, use 200 No Fruit rotten 10% fruit defects Monitor water Replace water
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
rinsing the use of poor quality ppm chlorinated water and quality regularly
and recycled water ensure removal of excess
water (drying)
Fruit storage Spoilage at non-ideal Cool rapidly (pre-cooling) Yes 10–12°C 12 ± 2°C Record storage Service coldroom
Quality assurance in agricultural produce,
temperature and store at optimal temperature regularly
(printed version published in 2000)
temperature and humidity continuously
ACIAR Proceedings 100
Ripening Uneven ripening, Induce ripening with ethylene Yes 50 ppm ethylene 3–4 days ripening Detect aroma of Use proper
overripe gas, monitor ripening stage ripened fruit ripening room
Cutting, Microbial contamination Monitor cleaning regime, i.e. No Unclean appliances Sanitised daily Inspection before Wash regularly
120
removal of (through hands, knives) sanitiser concentration usage
individual Microbial contamination Remove all peel, minimise Yes Unwashed raw Flesh in contact Inspection of flesh Wash raw fruit
fruitlets from peel contact with flesh fruit quality before cutting
Spoilage at non-ideal Operate in hygienic room Yes Temperature 20°C Airconditioned Record room Use hygienic
temperature with temperature at room temperature processing plant
15–18°C regularly
Packing Contaminated Ensure clean package, No Exposed package Factory cleaning Inspection of the Wash and dry
fruitlets packaging material monitor microbial quality package package
Spoilage due to Test packed sample for leaks, Yes Modified Modified Measure head- Use accurate MAPa
incorrect atmosphere monitor composition of atmosphere levels atmosphere limits space gases design
inside the package headspace gases regularly
Storage, Spoilage due to non- Monitor storage and handling Yes 2–5°C 5 ± 2°C Record Service all
distribution ideal temperature and temperature and humidity temperature facilities regularly
and retail humidity regularly
outlets
aMAP = modified atmosphere packagingTable 3. End-product specifications for minimally processed jackfruit .
Parameter Specification
Variety Yellow or orange-coloured flesh
Stage of ripeness Fully ripened but not overripe
Style of cut fruit Individual fruitlets with or without seeds
Quality of fruitlets Fruitlets to be of similar varietal characteristics, uniform colour and ripening stage,
reasonably uniform size and shape, fairly firm and free from injury or blemish, decay, disease,
moulds and other contaminants
Retail packaging Fruitlets to be packed in polypropylene containers with lids, polystyrene trays shrink-wrapped
with polyvinyl chloride (PVC)/stretch film or similar protective containers
Labelling Each container to be marked with the following information:
• Name of produce/variety
• Net weight in grams
• Date of packing/expiring
• Recommended storage temperature
• Name and address of packer/supplier
End-product inspection Conclusion
A record form should be prepared and completed by
trained staff to check end-product quality. The quality The safety of end product is one of the most important
should comply with the specifications outlined earlier quality aspects to be monitored in MP jackfruit. Mon-
by the producer. In the case of end-product quality itoring quality can be done using a QA system
below the specifications, a decision should be made approach starting from the receiving of raw materials,
whether to reject the product or return it to the through processing methods, packaging and storage,
processor for improvement. Quality certification and ending with end-product quality at retail outlets.
should be stamped on the box of the consignment as a The total QA approach implemented regularly will be
warranty to the distributors and buyers. able to provide consistent product quality and safety,
and hence extend buyers’ confidence to consume the
End-product management produce.
End products should be kept under chilled temper-
ature conditions to avoid deterioration and spoilage. It
Acknowledgments
is important to ensure that a ‘cool chain’ system be
used continuously during storage, handling, distri- The authors wish to acknowledge the Australian
bution and retailing of MP products. Temperature in Agency for International Development (AusAID) for a
the storage facilities and products should regularly be research grant through the ASEAN–Australia
monitored. Sample analysis should also be scheduled Economic Cooperation Program III project; Palamere
for stored products to evaluate quality and safety Pty Ltd (Australia) and all Australian technical spe-
levels. cialists for their assistance in managing the project; the
Federal Land Development Authority (FELDA), the
Documentation Federal Agricultural Marketing Authority (FAMA)
and all staff at Postharvest Handling and Minimal
An essential element of any QA system is that Processing Program, Malaysian Agricultural Research
records are maintained throughout all the processing, and Development Institute (MARDI), for their contri-
handling, storage and distribution stages. Records butions to the project.
should be clearly written, dated and signed by the
authorised person in charge of the operation. A
specially designed form for specific inspection and
analysis should be used to assist in standardising all
records.
121
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)References Minimal Processing of Tropical Fruits, Kuala Lumpur,
21–23 October 1997. Brisbane, Palamere Pty. Ltd.
Anon. 1997. Annual Report. Serdang, Selangor, Reyes, V.G. 1997b. Factors limiting shelf life and quality of
Horticulture Research Centre, Malasian Agricultural minimally processed fruits and vegetables. The
Research and Development Institute (MARDI). Association of South-East Asian Nations (ASEAN)–
Cantwell, M. 1996. Plant and worker sanitation: a brief Australia Economic Cooperation Program III: Quality
review. In: Fresh-cut products: maintaining quality and Assurance Systems for ASEAN Fruits (QASAF)
safety. Davis, University of California. Workshop on Minimal Processing of Tropical Fruits,
Kramer, A. and Twigg, B.A. 1970. Quality control for the Kuala Lumpur, 21–23 October 1997. Brisbane, Palamere
food industry. Wesport, Connecticut, AVI Publications. Pty. Ltd.
Natural Resources Institute (1994). Manual for horticultural Reyes, V.G. 1997c. Preservation technologies and systems
export quality assurance. Chatham, United Kingdom, for minimally processed fruits and vegetables. The
Natural Resources Institute. Association of South-East Asian Nations (ASEAN)–
Piccone, M. and Bunt, C. 1997. Understanding quality Australia Economic Cooperation Program III: Quality
systems. The Association of South-East Asian Nations Assurance Systems for ASEAN Fruits (QASAF)
(ASEAN)–Australia Economic Cooperation Program III: Workshop on Minimal Processing of Tropical Fruits,
Quality Assurance Systems for ASEAN Fruits (QASAF) Kuala Lumpur, 21–23 October 1997. Brisbane, Palamere
Project Workshop, Bangkok, 24–28 March 1997. Pty. Ltd.
Brisbane, Palamere Pty Ltd. SIRIM (Standards and Industrial Research Institute of
Reyes, V.G. 1997a. Current developments in minimal Malaysia) 1986. Specification for fresh jackfruit.
processing of fruits and vegetables. The Association of Malaysian Standard MS 1055. Shah Alam, Selangor,
South-East Asian Nations (ASEAN)–Australia SIRIM.
Economic Cooperation Program III: Quality Assurance Vinning, G. 1995. Report on a market study of minimally
Systems for ASEAN Fruits (QASAF) Workshop on processed tropical fruits. Brisbane, Palamere Pty Ltd.
122
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Minimally Processed Fruits in Singapore
Kalanithy Karichiappan, Lim Cheong Huat and Chew Siang Thai*
Abstract
A survey was conducted to study the quality and food safety status of minimally processed (MP) fruits in
Singapore. As the industry is still in its infancy, produce of this category is not widely available in the market
but is slowly gaining in popularity and the increasing demand has hastened its development. Several analytical
parameters of quality in fruit products were measured to determine quality changes, including physical
examination, pH, ethylene and oxygen gas levels, surface colour, total sugar, total acidity and water activity.
For contaminants, pesticide residues were measured and microbiological levels monitored using total plate
counts as well as counts of Escherichia coli, coliforms, Staphylococcus aureus, Lactobacillus and PPC
(psychrophilic count). Results obtained indicated that MP fruits in Singapore are relatively safe.
MINIMALLY processed (MP) fruits have gained popu- A survey was conducted on MP jackfruit and durian
larity in Singapore since their introduction a few years from September 1997 to June 1998 to study the quality
ago. MP fruits are prepared and packaged for con- and food safety status of MP fruits in Singapore.
venient consumption. Other advantages include
superior quality over processed fruits. However, the Materials and Methods
main disadvantage is their increased perishability and
shorter shelf life as compared to fresh whole fruits.
Minimal processing is defined as “all unit operations Materials
such as washing, sorting, trimming, peeling, slicing,
Several samples of MP jackfruit and MP durian
coring etc. that might be used prior to blanching in
were analysed for this study. The samples were either
conventional processing” (Rolle and Chism 1987) for
collected from a local MP plant or purchased from wet
the purposes of this paper.
markets and retail outlets to assess the microbiological
Presently in Singapore, there are five major sectors
and pesticide contamination as well as quality changes
of producers that are involved in MP fruits. These
in the retail outlets.
range from the small-scale fruit stalls that are located
in food centres, canteens and hawker centres to large-
scale operations such as that of the Singapore Airport Methods
Terminal Services in-flight catering centre. The rest
The microbiological tests undertaken included total
include fresh fruit shops, supermarkets and MP fruit
plate counts, and counts of Escherichia coli, col-
processing plants. Currently, all the sectors except the
iforms, Staphylococcus aureus, Lactobacillus and
MP fruit processing plants primarily aim to supply MP
PPC (psychrophilic count). Total plate counts were
fruits directly to the consumers. Thus, depending on
determined using the spiral plater system according to
the storage needs, attention has been focused to
the methods described in the Compendium of Methods
varying degrees by the different groups with a view to
for Microbiological Examination of Foods, American
extending the shelf life of this type of produce. One
Public Health Association (APHA) and the Associ-
major obstacle that limits the production of MP fruits
ation of Official Analytical Chemists (AOAC)
is the higher degree of perishability brought about by
Official Methods of Analysis. Total coliform and
damage to the fruit tissue during processing.
E. coli counts were determined using the Colitrak
* Veterinary Public Health Laboratory, Primary Production method which is based upon the widely used ‘most
Department, 51 Jalan Buroh, Singapore 619495. probable number’ (MPN) assay as specified in the
123
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Bacteriological Analytical Manual (Food and Drug Results and Discussion
Administration—FDA/BAM) and AOAC.
The pesticide residue analysis included testing for
organochlorine compounds, organophosphorus com- Packaging materials
pounds, pyrethroids, dithiocarbamates (as total CS2)
All of the MP fruits were packed in styrofoam trays
and N-methylcarbamates. Organochlorines were
with polyethylene film wrapping except for those
analysed by the multi-residue method. The organo-
which were sampled from ready-to-eat, cut fruit stalls
chlorines were extracted with acetonitrile, the water in
in hawker centres and food courts. The ready-to-eat,
the aqueous mixture was salted out, and the organic
cut fruit stalls pack the MP fruits in plastic bags or on
layer was dried and redissolved in hexane followed by
wooden skewers.
cleaning up with florisil solid phase extraction. The
eluent was injected for gas chromatography with an
electron-capture detector. The organophosphorous Physical quality attributes
compounds were extracted from the fruit samples with
ethyl acetate in the presence of anhydrous sodium General
sulfate and the filtered extracts were determined by Cutting and slicing of fruits has adverse conse-
gas chromatography using phosphorous-specific quences on product appearance. Cut surfaces bring
detection. Dithiocarbamate fungicides (Thiram, enzymes and substrates together which accelerate
Maneb, Zineb, Mancozeb, Ferbam, Manam, sodium browning. Most fruits have an active wound response
dimethyl dithiocarbamate and Ziram) were deter- mechanism, which is triggered by the production of
mined as carbon disulfide by the headspace gas wound ethylene. Ethylene can accelerate colour
chromatographic method with a flame photometric changes associated with ripening and senescence. Sig-
detector. N-methyl carbamates were extracted with nificant surface colour changes were observed for the
acetonitrile, the water in the mixture was salted out and jackfruit and durian samples. The surface colour
the organic layer was evaporated to dryness. The darkened from light yellowish-orange to a deep orange
residue was redissolved in methanol, followed by colour for the jackfruit within a day. The durian flesh
cleaning up with C18 solid phase extraction. The took a slightly longer time to change from light cream
eluent was injected for high performance liquid chro- to a yellow colour. These observations correlate well
matography (HPLC) using a machine equipped with a with the high level of ethylene gas detected in these
post-column derivation unit, and the carbamates were samples, which enhances the ripening process.
detected using a fluorescence detector. Pyrethroids Generally jackfruit were able to maintain good
were determined by gas chromatography with an appearance if stored at a refrigerated temperature for a
electron-capture detector method. All the pesticide week with a minimum amount of polyethylene pack-
residue analysis was done using multi-residue aging, as refrigeration delays senescence and
methods as described in Analytical Methods for polyethylene packaging reduces dehydration. After 7
Residues of Pesticides (Ministry of Welfare, Health days, some fluid had exuded from the jackfruit and
and Cultural Affairs, Rijswijk), fifth edition (1988). ‘off’ aromas became detectable.
For quality changes, pH, physical examination,
ethylene and oxygen gas levels, surface colour, total MP jackfruit
sugar, total acidity and water activity were monitored. Eleven samples of MP jackfruit were analysed. The
Surface colour was measured by using Minolta pH ranged from 5.07 to 5.77—which is within the
Chroma Meter CR300 based on the Hunter system. pH acidic range. The Brix value (dissolved solids) was at
was measured using a Fisher Accumet 950 pH meter a moderate level—13 to 22.5° and the acid content was
after calibration at 25°C. Total acidity was determined around 0.08 to 0.29%—which explains the observed
by a titration method using a standard sodium pH. The water activity results ranged from 0.94 to
hydroxide solution. Total sugar (°Brix) was deter- 0.99. The oxygen composition in some packages was
mined by refractometry utilising an Abbe reduced to as low as 6.3% (high respiration rate, rapid
refractometer. Water activity was measured using a oxygen consumption rate) and in some samples was as
LUFT Water Activity Analyser. Both ethylene and high as 19.8% (normal atmospheric oxygen compo-
oxygen gas levels were obtained by using a TEMAC sition is 20.8%). The ethylene results ranged from as
gas analyser. low as 300 ppm to as high as above 1,000 ppm (the
increase caused by the ripening process).
124
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)A series of experiments was also carried out in our contain either 0.6 or 0.9 ppm of dithiocarbamates (as
laboratory to evaluate the effect of temperature on the total CS2). All of the pesticides detected were within
respiration rate and ethylene production of MP jack- the Food and Agricultural Organization of the United
fruit. At 4°C, a significant reduction in both the Nations/World Health Organization (FAO/WHO)
oxygen uptake and ethylene emission was observed Codex Alimentarius Commission’s maximum residue
for the fruit. But more interestingly, when the chilled limits. The detection of the organochlorine
fruit was left at room temperature (25°C) for about 4 compounds in the fruits suggests that organochlorine
hours, the respiration rate reverted to the normal rate compounds (which were banned in the early 1970s in
and the oxygen in the package could be depleted to as many countries) are still persistently found in the
low as 5% while the ethylene level could reach a value environment.
of about 800 to 1,000 ppm.
The colour of the fruit (flesh) ranged from yellow to Microbiological contamination
orange–red. This correlates with measured surface
colour b* (the hue on the blue-to-yellow axis) which MP jackfruit
ranged from 36.74 (dull yellow) to 47.79 (deep Ten samples of MP jackfruit were tested. The
yellow) and surface colour a* (the hue on the green-to- results of the total plate counts ranged from < 5,000
red axis) which ranged from 0.2 (minimum redness) to organisms/g to 4.66 × 106 organisms/g. 6 out of 10
40.19 (moderate redness). Detailed results are given in cases (60%) had counts fractionally above the 1 × 105
Table 1. organism/g limit of Singapore’s Food Regulations.
Counts for psychrophiles, coliforms, E. coli and
MP durian Lactobacillus were acceptable. E. coli 0157:H7 was
Fifteen samples of MP durian were tested. Durian not detected in any of the samples tested. However, 4
samples had the highest pH among the samples we of the 10 samples had high counts of S. aureus
tested. The pH ranged from 6.45 to 7.57. In addition, a (ranging from 111 to 1,089 organisms/g). These would
high Brix value of >25° (17.5 to 36.88°) and a low total be probably due to contamination by the fruit handlers,
acidity value of about 0.03 to 0.33% were common for and might cause problems if these strains are entero-
the durian samples. This explains the higher pH values toxin-producing. Enterotoxins of S. aureus are very
observed. The water activity results ranged from 0.94 to stable. Taken together, the results suggest that the
0.98. The oxygen composition ranged from as low as jackfruit had been handled in a hygienic manner,
3.5% to as high as 19.1%. Ethylene gas levels were although the high counts of S. aureus might be cause
found to be well above 1,000 ppm for most durian for concern. Detailed results are given in Table 3.
samples. The colour of the fruit (flesh) ranged from light
yellow (creamy) to yellow. This correlates with MP durian
measured surface colour b* which ranged from 20.78 11 samples of MP durian were tested. The results of
(very light yellow) to 48.49 (yellow) and surface colour the total plate counts ranged from 5,000 to 2.89 × 107
a* which ranged from –4.52 to 2.8 (shades of red). organisms/g. The one excessively contaminated
Detailed results are given in Table 2. sample (2.89 × 107 organisms/g) would either have
experienced temperature abuse or have been handled
Pesticide contamination in a very unhygienic manner. Another of the durian
samples had an exceptionally high psychophilic count
Organophosphorus compounds, pyrethroids, dithio- of 1.49 × 106 organisms/g. Detailed results are given in
carbamates and N-methylcarbamates were not Table 4.
detected in any of the MP fruits. Only three samples of
jackfruit were found to contain 0.01 or 0.02 ppm of Reference
gamma-benzene-hexachloride ( -HCH). a Another
sample of durian was found to contain 0.01 ppm beta- Rolle, R.S. and Chism, G.W. 1987. Physiological
benzene-hexachloride ( -HCH)
` and 0.02 ppm quin- consequences of minimally processed fruits and vege-
tozene. Two samples of durian were also found to tables. Journal of Food Quality, 10, 157–177.
125
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)Table 1. Physical attributes results for 11 samples of minimally processed jackfruit.
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
Test Sample number
1 2 3 4 5 6 7 8 9 10 11
Colour of flesh pale yellow orange–red orange–red dull yellow yellowish orange orange yellow reddish reddish orange–
Quality assurance in agricultural produce,
orange orange orange yellow
(printed version published in 2000)
pH at 25°C 5.48 5.20 5.28 5.38 5.21 5.77 5.50 5.60 5.60 5.09 5.07
ACIAR Proceedings 100
°Brix 18.70 15.20 15.00 15.00 20.00 19.80 13.00 16.00 16.20 22.50 18.60
% citric acid 0.14 0.18 0.14 0.15 0.21 0.15 0.09 0.13 0.24 0.29 0.08
126
Water activity 0.99 0.97 0.99 0.97 0.96 0.99 0.98 0.97 0.98 0.96 0.94
% oxygen 19.80 16.90 6.30 19.30 17.10 6.30 15.60 15.60 14.80 15.60 11.30
Ethylene (ppm) 900 720 >1 000 300 1 000 1 000 650 650 495 >1 000 615
Surface colour L* 72.83 58.79 54.53 51.37 59.74 57.25 57.53 63.52 56.38 55.23 56.49
Surface colour a* 0.20 9.20 6.93 4.31 12.99 1.44 7.08 40.19 12.42 14.67 11.17
Surface colour b* 44.98 43.97 46.86 36.74 40.47 36.62 41.32 47.79 42.74 43.03 43.89
Surface colour C* 44.98 44.92 47.36 31.03 41.58 36.64 41.93 48.03 44.50 45.60 45.29
Hue angle (H°) 89.70 78.30 81.70 83.50 77.50 87.80 80.33 85.13 13.87 70.70 45.84
Notes on surface colour measurements: L* indicates lightness or darkness (0 = black, 100 = white); a* indicates the hue on the green-to-red axis (negative value = greenness,
positive value = redness); b* indicates the hue on the blue-to-yellow axis (negative value = blueness, positive value = yellowness); C* is the intensity of the hue [C* = (a*2 +
b*2)1/2]; and hue angle (H°) is the angle in the colour wheel of 360°(H° = tan–1b*/a*).Table 2. Physical attributes results for 15 samples of minimally processed durian.
Test Sample number
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Colour of flesha Y Y LY Y LY Y Y Y Y O Y Y Y Y Y
pH at 25°C 6.97 7.57 6.85 6.92 6.99 6.55 6.48 6.45 6.53 6.63 6.82 6.63 6.67 6.68 6.69
Quality assurance in agricultural produce,
(printed version published in 2000)
°Brix 29.40 33.00 30.00 29.80 26.70 36.88 25.25 25.20 17.50 27.50 22.50 28.50 25.80 21.00 22.00
ACIAR Proceedings 100
% citric acid 0.03 0.03 0.05 0.06 0.03 0.08 0.08 0.08 0.12 0.21 0.33 0.30 0.05 0.15 0.06
Water activity 0.97 0.94 0.98 0.97 0.98 0.96 0.97 0.94 0.96 0.95 0.97 0.98 0.97 0.97 0.95
127
% oxygen 11.20 14.20 19.10 4.30 14.50 8.60 13.60 19.10 6.80 5.80 12.50 4.10 12.00 4.90 3.50
Ethylene (ppm) >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 >1 000 770 775
Surface colour L* 72.56 70.76 75.07 73.40 76.42 75.18 74.30 71.40 58.87 51.39 45.85 51.72 64.35 55.69 46.03
Surface colour a* –1.46 –2.88 –2.54 –2.83 –4.52 –2.71 –0.75 2.40 0.26 2.80 –0.45 0.65 –1.48 0.26 0.60
Surface colour b* 25.66 24.61 20.78 23.90 29.75 27.15 48.49 40.27 40.21 34.91 31.54 41.16 39.78 28.45 22.79
Surface colour C* 25.70 24.77 20.93 24.13 30.09 27.29 48.49 40.34 40.21 35.03 31.56 41.16 39.82 28.46 22.80
Hue angle (H°) 93.20 96.60 96.90 96.70 98.60 95.67 90.80 93.36 89.70 85.27 90.97 89.20 92.50 89.57 88.47
aFlesh colour: Y = yellow, LY = light yellow and O = orange.
Notes on surface colour measurements: L* indicates lightness or darkness (0 = black, 100 = white); a* indicates the hue on the green-to-red axis (negative value = greenness,
positive value = redness); b* indicates the hue on the blue-to-yellow axis (negative value = blueness, positive value = yellowness); C* is the intensity of the hue [C* = (a*2 +
b*2)1/2]; and hue angle (H°) is the angle in the colour wheel of 360° (H° = tan–1b*/a*).Table 3. Microbiological results for 10 samples of minimally processed jackfruit.
Test (count) Sample number
1 2 3 4 5 6 7 8 9 10
Total plate count 6.2 × 105 2.18 × 105 40 000 1.11 × 105 47 600 1.57 × 105 < 5 000 < 5 000 4.66 × 106 9.48 × 105
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
Psychrophilic count (PPC) < 5 000 < 5 000 < 5 000 < 5 000 < 5 000 < 5 000 < 5 000 2.82 × 104 5 000 4.96 × 104
Coliforms 143 238 1 100 40 3Maturity Indices and Harvesting Practice of
‘Arumanis’ Mango Related to the Target Market
N.O. Tridjaja* and M.S. Mahendra†
Abstract
Mango as a climacteric fruit is frequently harvested when less than fully ripe. This is often necessary to obtain
optimal eating quality at the time of consumption where markets are a considerable distance from the place of
harvest.
In this study the age of fruit was calculated, based on the time of flowering. The orchard selected for the trials
was located in northern part of Bali, Indonesia. The laboratory analyses were carried out at Udayana
University.
The results showed that optimal maturity of ‘Arumanis’ mango for best consumption is when the fruit is
harvested 13–14 weeks after flowering. Fruit age has a close relationship with total soluble solids (TSS), total
acidity and pH content. This study found that ‘Arumanis’ mango is best for consumption when the TSS content
of the fruit is not less than 16.8°Brix, total acidity 0.18%, pH 4.8, flesh colour rating 6–6.5, and taste score 5.
MANGOES CAN be classified into two groups based on fruit quality (Kosiyachinda et al. 1984). Therefore,
their ability to reproduce from seed: monoembryonic there is a need to find objective measures which can be
and polyembryonic types. The major commercial used to determine fruit maturity in order to determine
cultivars in Indonesia, the Philippines and Thailand optimal harvesting time.
are of the polyembryonic type, while in Malaysia and Mango fruit traded commercially are commonly
Singapore, a mixture of polyembryonic and monoem- harvested green. Various methods for determining
bryonic seeds are extensively grown (Kusumo et al. maturity in mango have been proposed, namely,
1984). ‘Arumanis’ mango, which is classified as pol- softness of cheeks, peel colour, development of
yembryonic, is considered to have much commercial shoulder, specific gravity, and starch content.
potential. However, these methods have found limited com-
The definition of maturity as ‘the stage of devel- mercial application since they are mainly applicable to
opment giving minimum acceptable quality to the fruit that have reached an advanced degree of ripeness.
ultimate consumer’ implies a need for objective The objective of this trial was to study the maturity
measures of maturity. Indication of maturity is of con- indices and harvesting practice of fresh ‘Arumanis’
siderable importance during the marketing chain (Reid mango fruit related to the target market.
1985). Mango growers harvest fruit using their
judgement based on the appearance of the fruit. Con-
sequently, fruit harvested by conventional criteria may Materials and Methods
exhibit significant variations in both ripening rate and
Fruit were obtained from local farmers in the northern
* Postharvest Horticulture Division, Directorate of Farm part of Bali island, and the analyses were carried out at
Agribusiness and Processing Development, Directorate the Analytical Laboratory, Udayana University,
General of Food Crops and Horticulture, Ministry of Denpasar. Fruit were harvested at six stages of
Agriculture, Jl. Ragunan No. 15 Pasar Minggu 12520, maturity at one-week intervals: P1 = harvested 11
Jakarta, Indonesia.
† Horticulture Section, Department of Agronomy, Faculty
weeks after fruit set; P2 = harvested 12 weeks after
of Agriculture, Udayana University, Kampus Bukit fruit set; P3 = harvested 13 weeks after fruit set; P4 =
Jimbaran, Denpasar, Bali, Indonesia. harvested 14 weeks after fruit set; P5 = harvested 15
129
Quality assurance in agricultural produce,
edited by G.I. Johnson, Le Van To, Nguyen Duy Duc and M.C. Webb.
ACIAR Proceedings 100
(printed version published in 2000)weeks after fruit set; and P6 = harvested 16 weeks after nificantly decreased in fruit harvested at 13, 14, 15,
fruit set. and 16 weeks after full bloom. The lowest value for
On arrival at the laboratory, the samples of fruit weight loss was observed in fruit harvested at 16
were selected on the basis of good condition and even weeks after fruit set (4.92%), but was not significantly
maturity. Fruit of uniform size were selected. Each different to fruit harvested at 15 weeks after full bloom
fruit was carefully sorted according to visual (Figure 1).
assessment of its size, freshness and level of damage. The moisture content of fruit flesh increased slightly
After sorting, the fruit were washed, dipped in a with the increase in fruit maturation. Fruit harvested at
fungicide solution, and dried until the skin was dry. 11 weeks after full bloom showed the lowest moisture
The sample units were then randomly allocated to each content (8.74%), and the highest was in fruit harvested
treatment. A randomised block design was used which at 15 weeks after fruit set (Figure 1).
consisted of six treatments and four replicates. An
analysis of variance of data from the experiment was
carried out and where significance was shown, the data Fruit firmness
were further analysed using Duncan’s multiple range
test (Gomez and Gomez 1976) to determine the signif- ‘Arumanis’ mango does not lose its green colour
icance between individual treatments. even when fully ripe (Yuniarti 1980). The absence of
a quick visual index of ripeness in ‘Arumanis’ mango
Observations were made on weight loss, fruit
makes it difficult to ascertain the degree of fruit
firmness, total soluble solids, total acidity, vitamin C
ripeness without the use of destructive analytical pro-
content, pH, and organoleptic evaluation (colour and
cedures, although it is possible that firmness could be
taste). Observations on fruit freshness were carried out
used as an index.
daily to calculate the storage life.
Fruit firmness was highest in fruit harvested 12
weeks after full bloom (1.73 kg/cm2) and deterio-
Results and Discussion rated significantly as time to harvest after fruit set
increased. The lowest value was observed in fruit
Weight loss and moisture content harvested at 16 weeks after fruit set (Figure 2), but
was not significantly different to fruit harvested 13,
Weight loss decreased with the onset of fruit matu- 14 and 15 weeks after full bloom. Fruit harvested at
ration. The highest weight loss was observed in fruit 13 and 14 weeks after fruit set had fruit firmness
harvested at 11 weeks after fruit set (9.28%), and sig- values of 0.79 and 0.63 kg/cm2, respectively.
15 1.75
a 10 a
18 a
ab a a
Total soluble solids (°Brix)
b a ab
Moisture content (%)
12 8 15 1.4
Firmness (kg/cm2)
b
Weight loss (%)
c
b b 12 c
9 6 1.05
a a b b d d
9 b
6 4 0.7
6 b b b
Moisture content 2 TSS
3 3 0.35
Weight loss Firmness
0 0 0 0
11 12 13 14 15 16 11 12 13 14 15 16
Harvesting time (weeks after fruit set) Harvesting time (weeks after fruit set)
Figure 1. Weight loss and moisture content of Figure 2. Total soluble solids and fruit firmness of
‘Arumanis’ mangoes harvested at one-week ‘Arumanis’ mangoes harvested at one-week
intervals after fruit set. Points marked with intervals after fruit set. Points marked with
different letters are significantly different at different letters are significantly different at
the 5% level. the 5% level.
130
Quality assurance in agricultural produce,
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ACIAR Proceedings 100
(printed version published in 2000)According to Pantastico et al. (1984), compre- Total acidity
hensive studies on ‘Carabao’ mango showed that fruit
firmness decreased abruptly early in the ripening Total acidity decreased with the onset of fruit matu-
period, but continued to decrease with further ration. The highest value was in fruit harvested at 11
ripening. Softening changes in ripening mango have weeks after fruit set (0.98%), and significantly
been previously attributed to the activity of enzymes decreased in fruit harvested at 12, 13, 14, 15 and 16
that degrade pectic substances. In Malaysian ‘Aru- weeks after fruit set. The lowest value for total acidity
manis’ mango, the activities of pectin methylesterase was observed in fruit harvested at 16 weeks after full
and polygalacturonase were low in immature fruit, and bloom (0.13%), but this value was not significantly
increased with increasing physiological age. When different to fruit harvested at 13, 14 and 15 weeks after
harvested fruit were allowed to ripen under ambient full bloom (Figure 3). Kosiyachinda et al. (1984)
conditions, pectic enzyme activity initially decreased stated that titratable acidity decreases with the onset of
but then markedly increased in ripening fruit. maturation, however no common value for the
maximum titratable acidity exists that could be used to
Total soluble solids determine the earliest acceptable picking time.
Total soluble solids (TSS) increased with the onset Vitamin C content and pH
of fruit maturation. However, the highest TSS was
observed in fruit harvested at 14 weeks after fruit set The highest vitamin C content was observed in fruit
(16.96°Brix), and was significantly different to fruit harvested at 16 weeks after full bloom (161.7 mg/100
harvested at 11 and 12 weeks after flowering. The g), and the lowest value was measured in fruit
lowest value of TSS observed was of fruit harvested at harvested at 12 weeks after full bloom (85.8 mg/100
11 weeks after full bloom (11.72°Brix) (Figure 2). g). The vitamin C content increased as the time before
Pantastico et al. (1984) reported that total sugars and harvesting increased, except in fruit harvested at 15
soluble solids increased as the ‘Carabao’ mango fruit weeks after fruit set where the value decreased slightly
ripened, with the most marked increases occurring (123.2 mg/100 g) (Figure 3).
early in the ripening process. Mendoza et al. (1972) The pH of fruit flesh significantly increased with the
also found that the soluble solids content of mango onset of fruit maturation. Fruit harvested at 11 weeks
increased with the onset of maturation, however at after fruit set had the lowest pH (3.40), which was sig-
10–15 weeks after fruit set, the change in soluble nificantly different to fruit harvested at 13, 14, 15 and
solids did not show a consistent trend. 16 weeks after fruit set. The highest pH was measured
in fruit harvested at 16 weeks after fruit set (5.15)
(Figure 4).
165 1.36 6
Vitamin C content (mg/100 g)
Colour and taste scores
b ab a 9
a a
c a a
Total acidity (%)
a
b 1.02 4.5 a ab
110 b b
6
pH
b
d a a a a
d c
Vit. C content 0.68 3
Total acidity b
b d pH
55 3
0.34 1.5 b Colour score
a a a
Taste score
a
0 0 0 0
11 12 13 14 15 16 11 12 13 14 15 16
Harvesting time (weeks after fruit set) Harvesting time (weeks after fruit set)
Figure 3. Vitamin C content and total acidity of Figure 4. pH, flesh colour score and taste score of
‘Arumanis’ mangoes harvested at one-week ‘Arumanis’ mangoes harvested at one-week
intervals after fruit set. Points marked with intervals after fruit set. Points marked with
different letters are significantly different at different letters are significantly different at
the 5% level. the 5% level.
131
Quality assurance in agricultural produce,
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ACIAR Proceedings 100
(printed version published in 2000)Flesh colour and fruit taste Conclusion
Flesh colour was judged using a rating where: 1 = all The major chemical change in ‘Arumanis’ mango fruit
white; 2 = white with a slight yellow; 3 = whitest during growth and maturation was a regular increase
yellow; 4 = yellowish white; 5 = yellow with a slight of the level of reducing sugars throughout the devel-
white; 6 = all yellow; and 7 = yellowish red. The flesh opment period. It was expressed by a gradual increase
colour score significantly increased with the increase in total soluble solids up to maturity, a continued
in fruit maturation. The lowest colour score was decrease in fruit firmness, a decline in total acidity,
observed in fruit harvested at the earliest time of har- and an increase in pH and vitamin C content.
vesting (11 weeks after fruit set, with the score of 3.0 The results of the trial showed that the optimal
= whitest yellow), and the highest was in fruit maturity of the fruit for consumption was reached
harvested at 16 weeks after fruit set (7.0 = yellowish when fruit was harvested at 13–14 weeks after fruit set,
red) (Figure 4). characterised by the values of 16.8–17.0°Brix total
Fruit taste was judged using a rating where: 1 = soluble solids, 0.18–0.22% total acidity, pH 4.8, flesh
dominant sour; 2 = slightly sour; 3 = balance of sweet colour rating of 6–6.5, and a taste score of 5.
and sour; 4 = slightly sweet; and 5 = dominant sweet. In the absence of adequate objective measures of
The taste score significantly increased with the maturity, visual indicators are often employed, such as
increase in time after fruit set. The lowest taste score the shape of the fruit, the appearance of powdery
was in fruit harvested at 11 weeks after flowering (3.05 materials or bloom on the fruit surface, or the presence
= balance of sweet and sour), and the highest was in of plant sap at the fruit surface close to maturity.
fruit harvested at 13, 14, 15 and 16 weeks after fruit set
(5.0 = dominant sweet) (Figure 4). Acknowledgments
Storage life The authors wish to thank the Association of South-
East Asian Nations (ASEAN)–Australia Economic
Fruit storage life significantly decreased with the Cooperation Program III (AAECP–III) Quality
increase in fruit maturity. Fruit harvested at 11 weeks Assurance Systems for ASEAN Fruit (QASAF)
after full bloom showed the longest shelf life (9 days) Project for financial support of this work, and the Aus-
at room temperature (29 ± 1°C), while the lowest was tralian Centre for International Agricultural Research
observed in fruit harvested at 15 and 16 weeks after (ACIAR) for the presentation of this paper at 19th
fruit set (4 days) (Table 1). ASEAN/1st APEC Seminar on Postharvest Tech-
nology, Ho Chi Minh City, Vietnam. The authors also
wish to thank Prof. John Janes and Dr Zora Singh
(Curtin University of Technology, Australia) for their
helpful comments and Mr I.B.K.G. Kertia who typed
the manuscript.
Table 1. Storage life of ‘Arumanis’ mangoes harvested at one-week intervals after fruit set.
Treatment Storage life
Daysa LSR 5%
P1 (harvested 79 days afsb) 9.00 a
P2 (harvested 86 days afs) 7.00 b 0.36
P3 (harvested 93 days afs) 6.50 c 0.38
P4 (harvested 100 days afs) 5.00 d 0.39
P5 (harvested 107 days afs) 4.00 e 0.40
P6 (harvested 114 days afs) 4.00 e 0.40
a Values with different letters are significantly different at the 5% level.
b afs = after fruit set
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