Best Practices in Postharvest Management of Leafy Vegetables in Greater Mekong Subregion docx

Contents Part 1: Problems and Needs of Leafy Vegetable Value Chains in Poverty-stricken Upland Areas in CLV and Available Country Interventions 1 Problems and Needs of Leafy Vegetable

Best Practices in Postharvest

Management of Leafy Vegetables

in Greater Mekong Subregion

Countries

AVRDC - The World Vegetable Center

Shanhua, Taiwan

Best Practices in Postharvest

Management of Leafy Vegetables in Greater Mekong Subregion Countries

AVRDC - The World Vegetable Center

AVRDC - The World Vegetable Center is the leading international nonprofit organization committed to alleviating poverty and malnutrition in the

developing world through the increased production and consumption of safe vegetables

AVRDC - The World Vegetable Center

Editor: Maureen Mecozzi

AVRDC Publication Team: Kathy Chen, Vanna Liu, Chen Ming-che, Shiu-luan Lu

© 2009 AVRDC - The World Vegetable Center

Citation

Back (L-R): Mr Borarin Buntong, Cambodia; Mr Nguyen Dinh Hung, Vietnam; Dr Varit Srilaong, Thailand; Dr Kyaw Nyein Aye, Myanmar; Ms Luong Thi Song Van, Vietnam; Dr Sirichai Kanlayanarat, Thailand; Dr Li Hong, China; Dr Li YunShou, China; Mr Thongsavath Chanthasombath, Lao PDR; Mr Chansomone Phomachan, Lao PDR; Mr Nguyen Khac Trung, Vietnam; Mr Nguyen Duc Hanh, Vietnam

Contents

Part 1: Problems and Needs of Leafy Vegetable Value

Chains in Poverty-stricken Upland Areas in CLV and

Available Country Interventions

1

Problems and Needs of Leafy Vegetable Value

Chains in Selected Upland Areas in Cambodia

and Available Country Interventions

Mr Borarin Buntong

2

Problems and Needs of Leafy Vegetable Value

Chains in Selected Upland Areas in Lao PDR and

Available Country Interventions

Mr Thongsavath Chanthsombath

9

Problems and Needs of Leafy Vegetable Value

Chains in Selected Upland Areas in Vietnam and

Available Country Interventions

Dr Chu Doan Thanh

Postharvest Technologies for Fresh Leafy

Vegetables in Yunnan, China

Processing Technologies for Leafy Vegetables in

the Philippines and Other Parts of the World

Upland Agriculture Development in Yunnan, China

Acknowledgements

AVRDC - The World Vegetable Center and workshop participants gratefully acknowledge financial support from the Asian Development Bank through the RETA 6376 project The organizers also thank the people who assisted in the preparations for the workshop and who facilitated and accommodated the group during the study tour

Foreword

Postharvest technology (PHT) is crucial for perishable commodities such as leafy vegetables to bring down losses, improve marketing, and increase farm returns It is of particular importance in the Greater Mekong Subregion (GMS), one of the world’s leading vegetable producers and consumers, where the vegetable industry is seriously constrained by high postharvest losses and poor marketing systems Initiatives to promote the postharvest sector could fuel economic growth, promote rural sustainability, and ease the problems of poverty, unemployment, and malnutrition in developing countries PHT enables countries to participate effectively in domestic and international trade

in light of increased competition due to trade liberalization and market reforms

AVRDC - The World Vegetable Center designed and instituted two PHT initiatives for vegetables in GMS funded by the Asian Development Bank (ADB) The new ADB RETA 6376 project pursues PHT development for leafy vegetables, targeting small farmers and processors in upland areas in Cambodia, Lao PDR, and Vietnam This project complements the ongoing initiative on fruit and vegetables (ADB RETA 6208)

The ADB RETA 6376 workshop on Best Practices in Postharvest Management of Leafy Vegetables in GMS Countries held in Hanoi, Vietnam

on 25-27 October 2007 sought to build the groundwork for future PHT research and development work for leafy vegetables in the region The specific objectives of the workshop were to:

 examine the needs and problems of leafy vegetable farmers and other supply chain actors in upland areas of Cambodia, Laos, and Vietnam, and the existing country initiatives addressing those needs/problems

 review and document the fresh produce handling and processing technologies for leafy vegetables available in GMS and elsewhere

 identify PHT to be developed and formulate the R&D details

 foster regional cooperation to advance the vegetable industry in GMS countries

The workshop gathered PHT experts, key project players and other development workers in GMS to discuss and analyze the initial findings of surveys on leafy vegetable value chains in upland areas of Cambodia, Laos, and Vietnam Existing country interventions were examined in Session 1, and

experiences shared in postharvest handling (Session 2) and processing (Session 3) of leafy vegetables, including indigenous techniques and those in commercial practice with particular emphasis on simple, low-cost innovations Session 1 concluded with a list of priority problems/needs; Sessions 2 and 3 with postharvest handling and processing technologies to be developed by the Cambodia, Laos, and Vietnam teams, respectively Paper presentations preceded each workshop session

Best Practices in Postharvest Management of Leafy Vegetables in GMS Countries contains the papers presented in each session and the summary of

the following workshop discussion It has four parts: The first three parts correspond to the three workshop sessions, and the last part covers the concluding discussion, including a presentation about China’s experience in developing upland agriculture This proceeding can serve as a reference for development workers, policy makers and other stakeholders in developing countries aiming to strengthen the vegetable industry through improving value-addition activities after harvest

Dr Antonio Acedo, Jr

Dr Katinka Weinberger

AVRDC - The World Vegetable Center

PART I: Problems and needs of leafy

vegetable value chains in poverty-stricken upland areas in Cambodia, Laos, and

Vietnam, and available country

interventions

Problems and Needs of Leafy Vegetable Value Chains in Selected Upland Areas in Cambodia and Available Country

Interventions

Borarin Buntong

Postharvest Technology Laboratory Supervisor/Lecturer

and RETA 6376-Cambodia Team Expert Member

Faculty of Agro-Industry, Royal University of Agriculture

Phnom Penh, Cambodia

Mong Vanndy

National Coordinator, RETA 6376/ 6208 Project Deputy Director, Kbal Koh Vegetable Research Station

Department of Agronomy and Agricultural Land Improvement

Phnom Penh, Cambodia

Introduction

Cambodia is one of the least developed countries in the Greater Mekong Subregion It is located between latitude 10-15oN and longitude 102-108oE It has 24 provinces, three cities, and a total land area of 181,035 km2 The upland areas are located on the eastern side of the Mekong River

Vegetables rank second to rice among cultivated crops Total production area

is about 70,000 hectares with annual yield of 460,000 tons (FAO, 1999) Vegetables, particularly the leafy type, serve as a major source of income of many farmers and are the main and cheap source of nutrition for low-income families, especially those living in upland areas

Through the ADB-funded RETA 6376 spearheaded by AVRDC - The World Vegetable Center, development initiatives to introduce postharvest technology (PHT) and expand market opportunities for leafy vegetables were made possible, targeting small farmers and processors in upland areas in Cambodia, Lao PDR, and Vietnam A major initiative is the leafy vegetable value chain survey to gather benchmark information on present postharvest practices, problems, and needs of farmers and processors to be used as a basis

Vegetable Value Chain Survey

Priority leafy vegetables and survey sites

Survey site and crop priorities of Cambodia, Lao PDR, and Vietnam partners were set during the RETA 6376 Inception Workshop held on July 3-5, 2007

in Vientiane, Lao PDR For Cambodia, Kampong Cham and Siem Reap provinces were identified as the two upland survey areas; common cabbage and Chinese kale were selected as priority leafy vegetables (Fig 1)

Preparatory activities

Initial arrangement The RETA 6376-Cambodia team led by the National

Coordinator conducted an exploratory trip to the two provinces in September

2007 to identify specific areas in each province to be covered, make administrative arrangements with local authorities, and identify possible survey respondents

Figure 1 The two sites (Siem Reap and

Kampong Cham) and priority leafy vegetables of

the Cambodia surveys

Figure 2 Some postharvest practices for fresh leafy vegetables in Cambodia Top, l-r: field handling of harvested produce; sorting, trimming, cleaning; air drying Chinese kale leaves after washing

Bottom, l-r: packaging; transport

Survey questionnaire translation Two questionnaires, one for farmers and the

other for processors, sent by AVRDC headquarters (HQ) were translated into Khmer prior to the enumerators’ training

Enumerators’ training The training for survey enumerators was conducted

by the survey expert from AVRDC HQ in the Training Room of Kbal Koh Vegetable Research Station (KKVRS) on 24-28 September 2007 There were

11 participants from KKVRS and Department of Agriculture During the training, the Khmer translation of the farmer and processor questionnaires was checked, revised, pretested, and finalized

Conduct of survey

The survey in Kampong Cham was conducted on 1-5 October 2007 and the survey in Siem Reap was conducted on 6-9 October 2007 As planned, 100 respondents were covered in each province, for a total of 200 respondents However, the target number of processors was not met, similar to the Lao and Vietnam surveys Overall, only four processors of common cabbage (no processor of Chinese kale), all from Kampong Cham, were interviewed; the

Initial findings

The RETA 6376-Cambodia team expert member from the Royal University

of Agriculture who handled data input was trained by the AVRDC-HQ survey expert in survey data encoding The following are some initial findings of the survey:

Harvesting and field handling Harvesting of cabbage and Chinese kale is

done manually (Fig 2a) The time of harvesting depends mainly on the order from the collector The harvested produce may be left in the field to dry (cabbage) or brought to a packing area near the field Sometimes, packing is done in the field Some of the problems identified are as follows:

 improper maturity

 loose handling (no container)

 careless handling resulting in leaf crushing and/or head bursting

 exposure to the sun

Packinghouse operations, packaging, and transport At the packing area, the

produce is trimmed, cleaned, and sorted (Fig 2b-c) Some outer leaves of common cabbage are removed, while for Chinese kale, some farmers separate the leaves individually Cabbage usually is not washed; Chinese kale is washed and air-dried There is no quality standard used during sorting Collectors dictate quality criteria for acceptance The produce is transported unpacked, or packed in bamboo basket of different shapes and sizes (Figure 2d-e), plastic bags, or sacks Transport is done by small truck (Fig 2f) or motorcycle with or without trailer Some problems observed:

 large containers that could result in high compression damage and increase the tendency of handlers to drop the container due to its heavy weight

 overpacking of containers

 mixing of many types of containers of produce in the transport load without proper arrangement (improper stacking)

 overloading of transport load

 inability of plastic bag to protect the produce

 loose transport (produce transported without container)

 exposure to sun and rain during transport

 delays during transport or distribution

Storage Farmers do not have storage facilities The produce is kept in a

shaded area of the house or collected immediately by collectors and wholesalers Losses of produce during handling and transport to market are usually passed on by collectors and wholesalers to the farmers by requiring them to provide a weight allowance such as 1-3 kg additional weight per unit order

Processing Chinese kale is usually marketed and consumed fresh Cabbage is

consumed fresh and also is processed, mainly pickled (Fig 3) The usual procedure includes removal of outer leaves, slicing the cabbage head into quarters, salting, and fermentation for 1-2 days Aside from food safety concerns, some problems noted by processors include:

 short shelf life of 1-3 days

 fast color deterioration

 no uniform quality

 lack of skill and knowledge in processing

 no enough capital and lack of labor

General problems/needs The survey found that farmers and processors need

training in PHT to improve their knowledge and skills to operate a profitable enterprise, and require assistance in sourcing capital

Available Interventions Addressing Postharvest Problems

Some farmers use their own creativity to reduce losses of cabbage and Chinese kale as shown in Figure 4 Observed traditional innovations include:

 use of fresh banana leaves to line of bamboo basket to protect the produce from the sharp edges of the container

 proper arrangement of Chinese kale leaves inside the container to minimize leaf tearing and crushing

 individual wrapping of cabbage heads with old newsprint

 use of plastic bags to minimize weight loss, which is a form of modified atmosphere packaging

 exposing the cut butt end of cabbage heads to the heat of the sun for 1-2 hours before collection, to allow the cut end to dry and minimize

The fermentation process to produce pickled cabbage is a traditional

technique, although it needs improvement to address the problems

encountered

There is no PHT development for leafy vegetables in research and academic

institutions Aside from the scarcity of trained personnel in PHT, there is a

lack of funding support for leafy vegetable PHT research and development

Figure 3 Fermented common cabbage in retail

market display in Cambodia

Figure 4 Some indigenous/present postharvest techniques

for leafy vegetables

Problems and Needs of Leafy Vegetable Value Chains in Selected Upland Areas in

Lao PDR and Available Country

6376 and RETA 6208)

Vegetables are the second most important agricultural crops after rice Total cultivated area is 85,710 hectares, producing 744,450 tons of produce (DOA, 2005) Leafy vegetables account for about 50% of the total vegetable production, with area and volume of production of 45,240 hectares and 356,610 tonnes, respectively Vientiane Province is the major upland growing area, located north of the capital, Vientiane; Champasak is the leading vegetable-producing province at the southern tip of the country on the border with Cambodia and Thailand

PHT development for leafy vegetables was launched through RETA 6376 One major activity is the value chain survey targeting small farmers and processors in selected upland areas This paper presents some of the initial findings of the survey in Lao PDR

Vegetable Value Chain Survey

Priority leafy vegetables and survey sites

During the RETA 6376 Inception Workshop on July 3-5, 2007 in Vientiane,

common cabbage and Chinese/green mustard were identified as the priority

crops, while Vang vieng and Hinheub (in place of Kasy) Districts of

Vientiane Province were selected as the survey sites After further

consultation with the provincial agriculture agency, Kasy District was

reinstated as a survey site as originally proposed (Fig 1)

Preparatory activities

Initial arrangement The National Coordinator, Director-General of the

Department of Agriculture, and the RETA 6376/6208 Regional Project

Coordinator held a meeting with officials of the provincial agriculture agency

at the provincial capital, Phonhong The team received assurances of support

for the project and assistance in other requirements of the survey, such as

identification of respondents District agriculture staff (DAS) were selected to

be survey enumerators The DAS attended enumerators’ training a week later

Figure 2 Some postharvest practices for fresh leafy vegetables in Lao PDR Top, l-r: Loose hauling and packing in bamboo basket Trimming

of outer leaves and packing in plastic bag 68-kg capacity bamboo basket Bottom, l-r: Baskets of cabbages awaiting transport Truckload

of cabbages transported bare

Survey questionnaire translation Two questionnaires, one for farmers and the

other for processors, sent by AVRDC headquarters (HQ) were translated into Lao prior to the enumerators’ training

Enumerators’ training The training for survey enumerators was conducted

by the AVRDC HQ survey expert in the Training Room of the Crop Multiplication Center (CMC) on 4-7 September 2007 There were 10 participants, 6 DAS and 4 CMC staff including the National Coordinator The AVRDC-ADB Regional Project Coordinator and Small-scale Enterprise Advisor also attended some parts of the training During the training, the Lao translation of the farmer and processor questionnaires was checked, revised, pretested, and finalized

Conduct of survey

The survey in Kasy District was conducted on 10-14 September 2007 and in Vang vieng from 17-21 September 2007, with 100 respondents from each district, for a total of 200 respondents Due to a limited number of processors, only 18 processors of both cabbage and mustards were surveyed, eight from

Kasy and 10 from Vang vieng Selected project staff members were trained

by the AVRDC-HQ survey expert to use software for encoding survey data Initial findings

Farmers Figure 2 shows some of the postharvest handling practices for

cabbage Cabbages are loosely handled (without packaging containers), packed in big bamboo baskets (usually 68 kg capacity), or trimmed of outer leaves (wrapper leaves) before packing in plastic bags The major problems and needs of cabbage farmers obtained during the survey are:

 Overproduction: Cabbage usually is grown after rice during the dry and cool period of the year, from December to March When harvest time comes, there is an oversupply of produce and price of cabbage drops drastically

 Overmaturity: This is manifested as cracking and internal browning

of the cabbage head This is a frequent occurrence, as most farmers wait for the order from collectors and wholesalers rather than harvest the crop with no sure market

 Allowance for postharvest loss: Collectors/wholesalers usually require 25% allowance for losses incurred when handling the produce from the farm to the market Because they usually provide big plastic bags as packing material with 12-kg capacity, farmers fill each plastic bag with 15 kg cabbage Otherwise, collectors/wholesalers will not buy the farmers’ produce

 Losses due to the use of plastic bags: Use of plastic bags as packing material is beneficial in preventing too much water loss (weight loss) Cabbages are harvested in the morning (0800-1000), packed in plastic bags, piled along the road and sometimes covered by leaves, and picked up by the collectors in the afternoon (1400) Sweating inside the bag is common, a condition that favors rotting during subsequent handling Plastic bags cannot protect the produce from handling hazards resulting from mechanical damage High losses due to trimming of damaged leaves and rotten parts (due to bacterial soft rot) of the cabbage head are incurred (Fig 3)

 Need for storage facility: Farmers acknowledged that if they could store their cabbages for at least one month, they could have better control in harvesting and marketing their produce This is because after one month, the price of cabbage normally increases

Figure 3 Trimming losses in cabbage due to physical injury and rotting

and leafy wilting and yellowing in Chinese mustard

Figure 4 Lao technique in Chinese mustard fermentation

For Chinese/green mustard farmers, the major problems that contribute to postharvest loss are:

 Wilting, weight loss and yellowing of leaves (Fig 3)

 Insect damage

 No uniform size (small)

 Overmaturity: This is manifested by the production of flower stalks, because some farmers have to delay harvest to wait for orders from collectors and wholesalers

 Allowance for postharvest loss: For green mustard, farmers are required to provide1 kg allowance for loss per 12 kg plastic bag of produce For Chinese mustard, this is not required

 No storage facility: Farmers preferred to wait for orders from collectors and wholesalers rather than harvest the crop at the right maturity The practice of soaking stems in water can keep mustards for only one day; then, wilting and yellowing rapidly develop Farmers need to extend storage life of mustards

 Limited processing techniques

Processors Figure 4 illustrates the Lao technique in fermented mustard

processing, similar to that practiced for common cabbage Sorting is first done followed by separating individual leaves, washing, adding and mixing with salt, and fermenting in a pot for 1-2 days Prior to fermentation, the vegetable is mixed again with salt, monosodium glutamate, and rice water The major problems and needs of processors are:

 Improvement of technique

Available Interventions Addressing Postharvest Problems

Figure 5 shows some of the indigenous/traditional techniques of leafy vegetable farmers and processors observed during the survey

 Trimming cabbage and inverted positioning of head

 Water dipping and sprinkling

 Chinese mustard fermentation (Lao style) The technique is a traditional innovation gained through experience, but still needs improvement to solve or minimize the problems encountered

There are other interventions being instituted by some development agencies For example, the District Agriculture and Forestry Office (DAFO) has been implementing training programs on proper production of leafy vegetables including hygienic practices to assure food safety The National Agriculture and Forestry Extension Service (NAFES) is involved in promoting small enterprise through its ADB-funded Smallholder Project Some universities and development agencies (e.g FAO, NGO) are conducting training programs in processing techniques for vegetables However, PHT research and development interventions are lacking

Figure 5 Some indigenous postharvest techniques for fresh leafy

vegetables in Lao PDR

Conclusion

Postharvest handling and processing of the project’s priority leafy vegetables are far from ideal and losses could be very large, especially when there is an oversupply Some handling and processing techniques are used but may need

to be examined and improved to increase their effectiveness Other PHT techniques are needed and should be disseminated so that the quality and safety of the produce can be assured

Problems and Needs of Leafy Vegetable Value Chains in Selected Upland Areas in Vietnam and Available Country Interventions

Chu Doan Thanh, Ph.D

National Coordinator, RETA 6376/ 6208 Project Head, Department of Postharvest Technology Research Institute of Fruits and Vegetables (RIFAV)

Trau Qui, Gia Lam, Hanoi, Vietnam

Introduction

Vietnam is an agricultural country, with 75% of the population (or more than

62 million people) engaged in the agricultural sector In 2005, Vietnam’s agriculture contributed 19% of the country’s GDP Despite the great effort of the government to reduce the problem of malnutrition and poverty, the number of people living below the poverty line is still high, especially in remote and upland areas

Vegetables are one of the main sources of rural income To help farmers, particularly the vegetable growers in upland areas, increase their income and reduce rural poverty, the Asian Development Bank through AVRDC - The World Vegetable Center is implementing a number of technical assistance programs such as RETA 6208 “Improving rural livelihoods through development of vegetable-based postharvest technologies in Cambodia, Lao PDR and Vietnam (CLV)” and recently, RETA 6376 “Support of vegetable value chains in GMS countries for prosperity and poverty reduction.”

As one of the initial activities of RETA 6376, surveys of vegetable value chains in selected upland areas of Cambodia, Laos, and Vietnam were conducted In Vietnam, the national partner is the Research Institute of Fruits and Vegetables (RIFAV) This paper describes some preliminary findings of the survey conducted in Vietnam

Vegetable Value Chain Survey

Preparatory activities

Initial arrangement An exploratory trip to the selected survey sites, Lac

Thuy and Thanh Chuong districts, was conducted on 23-25 August 2007 by

the RETA 6376-Vietnam team led by the National Coordinator The team met and discussed with authorities and staff of local departments of agriculture, people’s committees, women’s associations, and farmer associations responsible for the agriculture sector in the two districts The local authorities strongly supported the activities of the project The team also received strong commitment from local authorities to provide necessary assistance during the implementation of project activities To better understand farmers’ needs and finalize the project’s priorities, the team also visited vegetable farmers and local markets where leafy vegetables are sold

Survey sites and priority leafy vegetables The exploratory trip finalized the

areas from each district to be covered in the survey and the priority leafy vegetables

Survey sites and farmers to be interviewed

Lac Thuy district: 100 farmers from four communes - Chi Ne town, Phu Lao, Lien Hoa, and Dong Tam

Thanh Chuong district: 100 farmers from four communes - Thanh Linh, Thanh Thinh, Thanh Lien, and Thanh Van

Priority leafy vegetables

Based on the discussion with local farmers and authorities, the priority leafy vegetables identified earlier during the RETA 6376 Inception Workshop on 3-5 July 2007 in Vientiane, Lao PDR, had to

be revised The final priority crops were:

Lac Thuy: 3rd week of September

Thanh Chuong: 4th week of September

Enumerators’ training To ensure smooth implementation of survey activities,

RIFAV in collaboration with AVRDC - The World Vegetable Center headquarters and AVRDC’s Laos-based ADB Postharvest Project Office

Technology During the training, the farmer and processor questionnaires were revised, pretested, and finalized

Conduct of survey

Although the RIFAV team was already experienced in conducting surveys based on previous experience in the RETA 6208 project, the team needed the expertise from the survey expert from AVRDC headquarters to refresh their knowledge and skills, which was achieved when the expert joined the team for some parts of the survey Highlights of the survey in each site are as follows:

Lac Thuy District

Date: 21-27 Sept 2007

Number of farmers interviewed: 88

Number of processors interviewed: 12

Total number of respondents: 100

Thanh Chuong District

Date: 29 Sept-5 Oct 2007

Number of farmers interviewed: 98

Number of processors interviewed: 2

Total number of respondents: 100

c) Handling and processing of leafy vegetables is far from ideal and losses could be very high, especially at peak season Main problems are rapid wilting, rotting, and inability to sell the vegetable at a good price due to lack of postharvest techniques such as storage, handling treatments, and processing

d) Some handling and processing techniques are used, but may need

to be examined and improved to increase their effectiveness

Available Interventions Addressing Postharvest Problems

There are already techniques in harvesting and field operations such as the right maturity, harvest time, harvest technique, harvest containers and tools to use, temporary storage in the field, and hauling the produce to the packing place Some farmers also clean, sort, trim, and/or bunch the produce RIFAV has also developed a simple, low-cost hydrocooling facility In packaging, some materials with specific shapes and sizes can be recommended, but may need to be examined for leafy vegetables Temperature and humidity control during storage and other measures such as avoiding exposure to ethylene sources, direct sun light and heat sources, and pests are available

In processing, RIFAV has developed a fermentation technique for Chinese mustard (Fig 1) The specifications of the technique are as follows:

a) Chinese mustard is usually harvested at a late stage of maturity to ensure soluble solids of 8-10%, of which sugar is about 4% and protein 1-2%—the most appropriate condition for lactic fermentation

b) Table salt: use dry salt without contaminating matter Do not use deliquesced salt for making a salt solution of 12-15%

c) Preparation of raw material: Old outer leaves and too young leaves

as well as rotten and heavily damaged leaves should be removed The upper parts of the leaves should be cut and set aside Long leaves are cut into shorter sections The Chinese mustard is washed with clean water to remove foreign matter, dust, and surface microorganisms The vegetable is dried by leaving in shade with natural air circulation until

no excess water is on the leaf surface Proper weighing is done for accurate preparation of recipe The weighed vegetable is loaded into a container made from plastic, glass, porcelain, etc

d) After packing the vegetable into containers, the container is filled with the prepared salt solution until all the vegetable is below the

e) Pressing: The container content is pressed by putting a load on the surface to the vegetable remains in the solution The load weight is calculated at approximately 50% of total vegetable weight

f) Storage: The pickled vegetable is ready after 6-8 days Care must be taken to ensure that foreign matter and other contamination sources do not fall into the container If black scum forms on the vegetable surface during pickling and storage the product should be removed immediately and discarded, and the container should be cleaned and sterilized

RIFAV has also developed a canning technique for fermented head cabbage and Chinese mustard Fermented leafy vegetables usually have a very short shelf life of up to 3-4 days There are other ways to prolong the shelf life and preserve the quality for up to six months using further processing techniques such as preserving in airtight pasteurized/sterilized containers like jars, cans,

or plastic pouches The technique is shown in Figure 2

Figure 1 Flowchart for Chinese mustard fermentation technique

developed at RIFAV

Figure 2 Flowchart for fermented cabbage and mustard canning

developed at RIFAV

The canning technique has the following procedures:

a) Good quality fermented head cabbage and Chinese mustard must be used b) Washing is done by soaking the vegetable in clean water for 5-10 minutes

to remove possible contamination matters

c) Surface drying is done with natural wind by leaving the fermented vegetables in the shade until there is no excessive water condensation seen on the product surface

d) Containers are cleaned and pasteurized Empty jars and plastic pouches are cleaned by brushing and sterilizing using steam

e) The jars/pouches are carefully loaded to full capacity with the fermented vegetable

f) Ingredients (salt, food acid, and preservatives): The concentration of solution depends on the acidity and salt contents in the fermented vegetables

In most cases, the solution contains 0.5% acidity and 4% salt Dissolve the ingredients in water, mix well, and filter it to remove dust and other foreign matter, and boil The containers with fermented vegetables are filled with the solution The solution temperature at filling should be around 80oC The filling volume should be as much as 40% compared to the container net weight To avoid re-contamination of products, the containers should be capped/sealed as soon as possible In most cases, capping is done manually For the plastic pouches, sealing is done by vacuum plastic sealer

g) Pasteurization: The pasteurization regime for glass jars (500 ml volume) is

as follows:

20′ – 20′ – 20′

- - - 78°C

The pasteurization regime for plastic pouches (500 g) is as follows:

15′ – 20′ – 30′

- - - 78°C

h) Cooling: After pasteurization, the products should be cooled down as soon

as possible until the containers’ surface temperature reaches about 40oC i) Temporary storage: As usually practiced, the products are subjected to

Workshop Summary

Summary of problems/needs of farmers and processors based on leafy vegetable value chain surveys of Cambodia, Laos, and Vietnam partners and available country interventions

Country Chain Level Problems/Needs Existing/Developed

Techniques

Harvest/field: proper maturity; damage (leaf crushing/tearing, head bursting) due to careless operation and loose handling (without container);

wilting due to exposure to sun and delays

Cabbage head with cut butt end exposed

to sun right after harvest and before collection, apparently

to allow drying up of the butt end to discourage soft rot development Farmers

Packhouse, Storage, Transport: over-trimming, loose handling, improper container (too big, use of sack, improper stacking, overloading; no storage facility /technique; rotting, wilting and yellowing result

to trimming losses

Use of plastic bag (modified atmosphere packaging or MAP) with individual wrapping with newsprint

Cambodia

(common

cabbage;

Chinese kale)

Processors Fermented cabbage: short

shelf life of 1-3 days; not uniform quality

Other processed products:

no processing technique for Chinese kale and

dehydration technique in cabbage

Traditional fermentation/pickling method

Country Chain Level Problems/Needs Existing/Developed

Techniques

Cabbage: During supply (production peak), need storage for at least one month when prices start to

over-go up; Over-maturity (cracking and internal browning) as farmers wait for order rather than harvest the crop; plastic packs (MAP films) provided by collectors but high transport losses due to damage (plastic bag could not protect produce from handling hazards) and rotting (favored by sweating inside the bag); losses passed on to farmers providing 25% allowance for loss (e.g for 12 kg pack, 3

kg more added)

MAP Farmers

Chinese/green mustards:

losses due to over-maturity (flowering), yellowing, wilting; for green mustard, 1

kg allowance for loss per 12

Fermentation method

Farmers General needs: proper

harvest/field operations, postharvest treatments, packaging, storage; specific problems similar to

Cambodia and Lao situations

Proper handling recommended elsewhere usually adapted by farmers

Fermentation technique at RIFAV; plastic packing, bottling, canning to prolong shelf life

PART II: Postharvest technologies for fresh leafy vegetables

Postharvest Technologies for Fresh Leafy

Vegetables in Yunnan, China

Chen ZongQi

Associate Professor Agricultural Environment and Resources Research Institute

Yunnan Academy of Agricultural Sciences

Kunming, Yunnan, China

Introduction

China produces more than 583 million tons of vegetables per year, or nearly 50% of the world’s production However, postharvest losses are a significant problem and are estimated at 25-30% of production, accounting for more than

70 billion yuan (>9 billion USD) per year

Yunnan Province grows a number of vegetables on about 583,000 hectares, producing about 10.4 million tonnes for domestic use, to supply other provinces, and for export The main vegetables are as follows:

Leafy vegetables: lettuce (head and leaf types to Southeast Asia, Japan, Hong

Kong, Beijing, Shanghai, Guangdong), cabbage (Shandong,

Guangdong), celery (Singapore, Malaysia, Hong Kong, Shanghai, Beijing, Guangdong, etc.), spinach (Hong Kong, Guangdong, etc.)

Fruit vegetables: sweet bean (Japan, Taiwan), eggplant and bitter gourd

(South China), tomato (around China and Southeast Asia), sweet pepper (Japan, Shanghai, Hong Kong, Guangdong)

Flower vegetables: cauliflower (Malaysia), broccoli (Japan, Singapore,

Beijing, Shanghai, Hong Kong, Guangdong)

Root, bulb, and tuber crops: radish (Japan, South Korea, Guangdong), carrot

(Thailand, Shandong, South China), potato (Southeast Asia, around China), onion (South Korea, Japan, Russia, North China), garlic and ginger (South Korea, Middle East countries, Shandong)

Yunnan produces two types of common cabbage; the big variety, mainly for pickle and dried product processing, and the small variety for the fresh market Chinese cabbage and leaf mustard are produced for fresh

Proper postharvest handling of fresh vegetables is important to reduce losses between harvest and consumption, maintain quality (appearance, flavor and nutritive value), and ensure safety of the produce The Yunnan provincial government promotes and supports the development and use of appropriate postharvest technologies to improve quality and market competitiveness of vegetable produce Government research and academic institutions are spearheading technology development and extension to farmers and other industry users These development efforts yielded good results, but are not yet sufficient to address the needs of the vegetable industry Most vegetable farmers and marketers rely on their own techniques to reduce losses and improve marketability of their produce

This paper presents some technologies developed and techniques used by farmers in the handling and marketing of fresh leafy vegetables Some techniques described here are recommendations, rather than products of research

Postharvest Losses

Postharvest losses of leafy vegetables in Yunnan, China have not been assessed and quantified However, the problem is prevalent and serious, as farmers incur trimming losses and losses due to wilting and bacterial soft rot (Fig 1) Leaf yellowing, tearing, crushing, and head bursting (in the case of common cabbage and heading type of Chinese cabbage and lettuce) are also common and contribute to losses

Postharvest Techniques

Harvesting

Because of the climate and mountainous terrain of the province, common cabbage, Chinese cabbage, Chinese kale, and mustards are planted and harvested year-round in Yunnan

Harvest maturity of leafy vegetables is estimated based on appearance and/or firmness If some of the leaves turn yellow, it means the vegetable is ready for harvest In common cabbage and Chinese cabbage, the head is pressed lightly

by hand; if it is tight and hard, the vegetable is already mature In certain cases, sample heads of common cabbage or Chinese cabbage are cut into two parts to observe the internal stem; if the stem is too long, the head is already overmature Harvesting is done by hand with the use of a knife The harvested produce is then placed in collection containers, which may be plastic crates or bamboo baskets with cotton or paper cushioning or padding The packed