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PACKAGING TECHNOLOGY AND SCIENCE Packag Technol Sci 2005 18 125 131 Published online 7 March 2005 in Wiley InterScience DOI 10 1002 pts 681 Packaging Performance Comparison for Distribution and Export of Papaya Fruit By Vanee Chonhenchob1and S Paul Singh2 1Department of Packaging Technology Kasetsart University Bangkok 10900 Thailand 2School of Packaging Michigan State University East Lansing MI 48824 USA This paper presents the development and testing procedures for new packaging systems for papaya fruit Papaya is a nutritious tropical fruit consumed both in its fresh form and as a processed product worldwide Thailand is a major exporter of fresh and processed papayas from Asia Major quality indices for papayas include colour size fi rmness and freedom from defects and decay A high percentage of post harvest losses of papaya fruits have been reported as exports have increased Mechanical damage is one of the major causes of the quality loss of papaya fruits therefore proper packaging is demanded for better protection In addition other criteria are important to meet consumer acceptance New packaging systems for papayas were compared with the existing systems currently used for local markets The packaging systems were evaluated in terms of physical protection heat transfer characteristics for rapid cooling and maintaining optimum temperature and relative humidity during post harvest quality maintenance and marketing issues Two cushioning systems foam nets and paper based wrap materials were also compared Actual shipment and vibration tests were performed and the effect on quality was determined The new packaging systems tested showed better protective performance and improved quality parameters as compared to existing systems Minimized mechanical injuries resulted in a decreased susceptibility to decay and bruising Paper based cushions showed similar protection to plastic foam nets materials but offered a better ripening response for papayas The data were compared to seek an optimum packaging system for papayas based on the various criteria Copyright 2005 John Wiley Revised 3 September 2004 Accepted 6 December 2004 KEY WORDS papaya RPC packaging system heat transfer post harvest losses mechanical damage Correspondence to S P Singh Department of Packaging Technology Kasetsart University Bangkok 10900 Thailand Email singh msu edu Copyright 2005 John Wiley 15kg or rectangular Thai RPC for the Solo type RPC TH B 15kg 2 RPC US A 7kg 3 RPC US B 20kg 4 RPC US C for Solo type 10kg 5 corrugated fi breboard box CFB 15kg Effects of cushioning systems were also determined Foam nets and paper wrap materials were compared The various packaging systems tested are shown in Figure 1 Real life shipment and vibration tests Real life shipment and laboratory vibration tests were per formed to compare the protective performance of various shipping containers Real life shipments represent transportation and handling methods used in existing produce distribution methods in Thailand For real life shipment handling and distribution systems of papayas as previously observed were simulated Papayas in different packaging systems were transported from the orchard to the laboratory at Kasetsart University in Bangkok Vibration tests in accordance with ISTA Project 1A were also performed 5The packaging systems were subjected to a fi xed vibration frequency at 4 Hz 240RPM for the duration of 1h After simu lated tests the papayas were evaluated for per centage losses in quality The papayas were stored at ambient temperature 28 32 C Export markets New packaging systems for papayas for export Based on the test results for local markets and based on the packaging requirements discussed with growers distributors and exporters a new V CHONHENCHOB AND S P SINGH Packaging Technology and Science Copyright 2005 John Wiley 18 125 131 Copyright 2005 John Wiley 18 125 131 PERFORMANCE COMPARISON OF PAPAYA PACKAGING Packaging Technology and Science RPC TH A Khagdum Paper based RPC TH B Solo Foam net RPC US A Solo Foam net RPC US B Khagdum No cushion RPC US C Solo No cushion CFB Khagdum No cushion Figure 1 Packaging systems tested packaging system was developed for papaya export The new packaging system was compared to the existing systems by performing vibration tests Papayas were evaluated for percentages of quality loss as a function of package type Heat transfer characteristics In addition to the shipping tests all packaging systems were examined for their heat transfer characteristics according to the method of Singh 1992 6The com plete method of determining 7 8 cooling time has been described and cited by Singh6and has been used to compare package performance in earlier studies on strawberries bananas and mangoes It represents the time required to drop seven eighths of the temperature difference between the fruit temperature at the start of the test and the fi nal desired cooling temperature The temperature of the fruit was measured at the centre location of the fruit using an Omega probe thermometer with an accuracy of 0 05 C in the measuring range see top right panel Figure 1 Optimum storage tempera ture for papayas was 10 13 C The seven eighths cooling time was calculated based on the data on temperature profi les RESULTS AND DISCUSSION Post harvest losses of papaya at local markets Papayas at local markets in Thailand showed a range of defects summarized in Table 1 Major post harvest losses were mechanical injuries scarring decay and skin abrasions The values of percentage damage for each category are listed based on the entire shipment evaluated e g the Khagdum variety showed that on average 38 of all fruit inspected showed bruising 30 5 of all fruit inspected showed abrasion damage 20 of all fruit showed scarring defect and so on These percentages cannot be added since a fruit may have multiple defects and therefore may be counted under more than one defect category Packaging systems for papayas for local markets Shipping containers used for papayas in Thailand vary among users Mostly Khagdum papayas are vertically packaged with the bottom end down in round RPC RPC TH A while Solo papayas are vertically packaged in rectangular RPC RPC TH B with foam nets wrapped on each fruit According to discussions with growers distri butors wholesalers retailers and consumers the packaging requirements for papaya for local markets can be summarized as follows 1 Provide ergonomic fi eld picking and handling 2 Protect papaya fruits from bruising and abrasion 3 Provide stackability 4 Optimize good ventilation with minimized weight loss 5 Provide approximate capacity of 15 20kg 6 Offer symmetrical packing arrangement and sales appeal V CHONHENCHOB AND S P SINGH Packaging Technology and Science Copyright 2005 John Wiley 18 125 131 Table 1 Post harvest losses classifi ed by types of defects at wholesale and retail levels Post harvest losses KhagdumSolo Types of defectsWholesaleRetailAverageWholesaleRetailAverage Bruise354138293130 Abrasion293230 5273129 Scarring211920121614 Decay223830162420 Overripe6118 5486 Uneven skin colour151213 5856 5 Real life shipment and vibration tests After real life shipment and vibration tests papayas packaged in different types of shipping containers and cushioning systems were stored at ambient temperature Mechanical injuries on papayas were evaluated after storage for 2 days when these damages were clearly visible The results from vibration tests corresponded with those from real life shipment tests Table 2 shows the percentage mechanical damage after vibration tests of Khagdum and Solo papayas For Khagdum papayas RPC US C and RPC US A showed the best protective performance against mechanical damage followed by RPC US B and CFB respectively The highest degree of mechani cal damage was observed in a current used prac tice in which Khagdum papayas are packed in a vertical orientation in RPC TH A Bruises occurred around the fruit particularly at the bottom end Papayas in RPC TH A packaged in a horizontal orientation had less mechanical damage compared to vertical placement Fruit orientation in the pack ages affects the degree of bruising Vertical place ment is not suitable for Khagdum papayas In all shipping containers tested papayas wrapped with foam nets and paper based materials had the lowest percentage of mechanical damage The results showed no signifi cant differences p 0 05 between the two cushioning systems on damage levels RPC TH B was currently used for Solo type papayas As shown in the results similar trends to Khagdum papayas were observed in Solo papayas except that vertical placement was appropriate for the Solo type RPC US C and RPC US A showed better protection against mechanical damage as compared to RPC US B and CFB The highest degree of bruising was observed in RPC TH B The results also suggested that the Solo type papaya is less susceptible to mechanical damage than the Khagdum type Ripening is an important process directly related to papaya quality The results showed different ripening levels of papayas in various packaging systems In general papayas placed in the bottom layers tended to have a higher ripening rate than those in the top layers However uniform ripening was only observed in RPC US A double layer placement and RPC US C single layer place ment In addition papayas wrapped with paper based materials showed more uniform ripening than those with foam nets Mechanical damage is one of the primary criteria for the rejection of papayas at destined markets The results also suggested the possible effects of mechanical damage on other defects such as decay abnormal ripening and softening Mechanically injured papayas showed a higher degree of such defects than intact fruits after storage for a few days Packaging systems for export markets There have been reports of high percentages of mechanical damage of papayas at export markets Copyright 2005 John Wiley 18 125 131 PERFORMANCE COMPARISON OF PAPAYA PACKAGING Packaging Technology and Science Table 2 Damage levels of papayas in various shipping containers after vibration tests Degree of mechanical damage KhagdumSolo Package typeNo cushionFoam netPaper basedNo cushionFoam netPaper based RPC TH A vertical 594952N AN AN A RPC TH A horizontal 453835N AN AN A RPC TH BN AN AN A453639 RPC US A251512211210 RPC US B vertical 473536393032 RPC US B horizontal 413028N AN AN A RPC US CN AN AN A21911 CFB513942423835 Papayas need to be repackaged by local compa nies Current packaging systems used for export ing papayas vary among exporters There has been a demand for proper packages for exporting papayas To obtain feedback a panel of 18 distributors and exporters were surveyed for input According to the results from the study for local markets and the discussion with this panel of distributors and exporters the required features for packaging systems for papayas for export markets are 1 Package papayas in a single or double layer 2 Offer protection against mechanical damage throughout handling and distribution systems 3 Provide stackability 4 Offer good cooling performance 5 Provide approximate capacity of 8 15kg 6 Offer symmetrical packing arrangement and sales appeal The new packaging systems were corrugated fi bre board boxes of inside dimensions 58 49 15cm for Khagdum and 58 37 15cm for Solo papayas Both types were packaged in a single layer with paper based wrap materials Khagdum papayas were packaged in a horizontal orientation while Solo papayas were packaged in a vertical orienta tion with the bottom end down The results after vibration tests showed that damage levels to papayas packaged in the new systems were sig nifi cantly reduced Mechanical damage was 4 12 in Khagdum and 2 10 in Solo types The degree of loss in the new packaging system will be further investigated based on actual export shipments Heat transfer characteristics Prompt cooling was recommended to maintain the quality of fruits after harvest The optimum tem perature for papayas is 10 13 C The heat transfer characteristics of tested shipping containers are shown in Table 3 The results show that all RPC types except RPC TH A no hole can be used properly for prompt pre cooling and maintain ing optimum temperature and relative humidity during handling and distribution This character istic plays an important role in controlling decay and diseases Khagdum papayas had about twice the cooling rate of the Solo type CONCLUSIONS Papayas are highly sensitive to mechanical damage Proper packages with cushions results in reduced damage improved marketability and prolonged shelf life of papaya fruits at local and export markets According to the results from the present study single layer placement of papayas at optimum maturity stage with cushioning is recommended for best quality V CHONHENCHOB AND S P SINGH Packaging Technology and Science Copyright 2005 John Wiley 18 125 131 Table 3 Rate of cooling 7 8 cooling time of various shipping containers for papayas Seven eighths c