Đề tài Mango Postharvest Manual - Version 1

i Mango Postharvest Manual CARD Project 050/04VIE Version 1 APRIL 2007 By Dr. Roberto Marques, Dr. Peter Hofman, Robert Nissen QDPI&F Ministry of Agriculture & Rural Development ii © The State of Queensland, Department of Primary Industries and Fisheries [2007]. Copyright protects this work. Except as permitted by the Copyright Act 1968 (Cth), reproduction by any means (photocopying, electronic, mechanical, recording or otherwise), making available online, electronic transmission or other publication of this work is prohibited without the prior written permission of The Department of Primary Industries and Fisheries, Queensland. Inquiries should be addressed to copyright@dpi.qld.gov.au (Ph: +61 7 3404 6999). iii CARD VIETNAM 2006 MANGO POSTHARVEST TRAINING MANUAL 1 Introduction................................................................................................1 2 Key production practices affecting postharvest quality .............................2 3 Know your mango (postharvest biology)...................................................3 3.1 Fruit ripening and quality loss ..........................................................3 3.1.1 Respiration rate................................................................................3 3.1.2 Ethylene production .........................................................................4 3.1.3 Loss of water (transpiration) ............................................................4 3.1.4 Fruit changes during ripening ..........................................................5 3.2 Main causes of quality loss after harvest.........................................5 3.2.1 Inadequate temperature control.......................................................5 3.2.2 Mechanical damage .........................................................................5 3.2.3 Sapburn and skin browning .............................................................6 3.2.4 Postharvest diseases and physiological disorders ..........................7 3.2.5 Treatment injuries ............................................................................7 4 Take care of your mango (postharvest technology)..................................9 4.1 Harvesting and field handling...........................................................9 4.1.1 When to harvest your mango...........................................................9 4.1.2 How to recognise when mango fruit are mature: maturity indices...9 4.1.3 How to harvest your mango ...........................................................10 4.1.4 Desapping ......................................................................................11 4.1.5 Field packing and transport............................................................13 4.2 Packhouse operations and practices.............................................13 4.2.1 How to sort/grade your mango.......................................................13 4.2.2 How to pack and label your mango................................................15 4.2.3 Postharvest treatment to control rots .............................................16 4.2.4 General recommendations for the packing shed...........................16 4.3 Ripening and storage of your mango.............................................17 4.3.1 Temperature management ............................................................17 4.3.2 Pre-cooling and transport...............................................................18 4.3.3 Forced-air cooling ..........................................................................18 4.3.4 Guidelines for temperature management ......................................19 4.3.5 Controlled ripening .........................................................................21 4.4 How to transport your mango to the retailer ..................................21 4.5 Know your market (customer requirements)..................................21 iv 5 Causes and solutions of the main postharvest defects of your mango ..23 5.1 Anthracnose ...................................................................................23 5.1.1 Treating fruit with a hot dip.............................................................24 5.1.2 Treating fruit with a flood spray......................................................25 5.1.3 Sanitation .......................................................................................25 5.2 Stem end rot...................................................................................26 5.3 Bacterial black spot ........................................................................27 5.4 Sapburn..........................................................................................28 5.5 Skin browning.................................................................................29 5.6 Sunburn..........................................................................................30 5.7 Abrasion damage ...........................................................................31 5.8 Pressure damage...........................................................................32 5.9 Impact damage ..............................................................................33 5.10 Rhizopus rot ...................................................................................34 5.11 Black mould....................................................................................35 5.12 Alternaria-rot...................................................................................36 5.13 Stemphylium rot .............................................................................37 5.14 Sooty mould ...................................................................................38 5.15 Grey mold.......................................................................................39 5.16 Blue mold .......................................................................................40 5.17 Mucor rot .......................................................................................41 5.18 Cytosphaera rot..............................................................................42 5.19 Lenticel spotting .............................................................................43 5.20 Abnormal ripening ..........................................................................44 5.21 Jelly seed .......................................................................................45 5.22 Stem end cavity..............................................................................46 5.23 Internal breakdown.........................................................................47 5.24 Chilling injury..................................................................................48 5.25 Heat injury ......................................................................................49 5.26 Failure of skin to yellow..................................................................50 5.27 Fumigant injury...............................................................................51 5.28 Fruit fly damage .............................................................................52 5.29 Mango seed weevil damage ..........................................................53 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 1 1 Introduction The successful marketing of fresh fruit requires careful attention to detail during production to produce a quality fruit, and also during postharvest to reduce loss of quality of the harvested fruit. After spending a lot of time, effort and money on crop production, it is logical also to spend resources to protect the value of the product after harvest. Fresh mango fruit are highly perishable, especially in tropical environments because of high temperatures. Care needs to be taken during harvesting, handling, transport, and distribution to ensure that the fruit reaches the consumer in good condition. Growers, collectors, traders, and retailers should receive appropriate instruction on how to use the most appropriate postharvest practices, based on the characteristics of the product, needs of the customer, cost of technology, and market conditions. This manual presents the basic principles of postharvest biology that affect fruit quality, as well as the key postharvest practices that should be used to ensure quality mango are marketed. Commercial practices were organised in a sequence aimed at maximising costumer satisfaction, highlighting the benefits and providing practical recommendations for each step from harvest to customer. The causes and solutions of most postharvest defects of mango are presented. This document is not intended to be an exhaustive book on mango postharvest, but will summarise the key issues as they relate to improving existing supply chains in Vietnam. More detailed information is available in the Vietnamese translation of the Queensland DPI&F Agrilink Mango Information Kit. CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 2 2 Key production practices affecting postharvest quality Although good postharvest practices are essential to reduce quality loss during handling and distribution, they cannot improve fruit quality beyond that achieved at harvest. The application of good crop management practices is essential to ensure good quality at harvest. Major postharvest problems relating to disease, insects, and fruit appearance can be reduced by good production practices. Some of the main production practices that affect mango fruit quality are: • Use of appropriate cultural practices that allow healthy tree and fruit development, including a balanced fertilisation program (especially nitrogen and calcium), proper irrigation (if necessary), and tree canopy management to ensure that pest and diseases can be managed well, and harvesting is efficient. • Orchard hygiene to reduce fungal infections that start on the fruit on the tree, and insect damage. These practices include removing fruit left over on the trees or on the orchard floor, removing dead branches that can contain fungal spores, and cleaning bins or containers that have been in contact with soil. • Disease management (especially anthracnose) through an effective spray program aimed at reducing infection of flowers and fruit. • Integrated pest management (IPM) to monitor and control orchard pests such as fruit flies, seed weevils, scales and other pests that cause skin defects that reduce fruit quality. The above is a very brief summary of the importance of good production practices in producing quality fruit. More detailed information on these practices can be obtained from the Vietnamese translation of the Queensland DPI&F Agrilink Mango Information Kit. CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 3 3 Know your mango (postharvest biology) 3.1 Fruit ripening and quality loss There are many reasons for quality loss after harvest. Some of these are the result of the normal processes of the fruit as it "moves" from the unripe to the ripe, then to the senescent or decayed state. These processes cannot be stopped, but we can use practices to minimise or slow down these processes to extend the life of the product. Others factors that reduce quality are the result of external practices which adversely affect the produce, and which need to be minimised or managed appropriately. Figure 1. Maturity and ripening in relation to other stages of the fruit growing process. The major factors that affect quality after harvest are: 3.1.1 Respiration rate Fruit are alive and continue to have active biological processes operating after harvest. The process of senescence (aging leading to death) commences immediately after harvest. This process of deterioration has to be managed to reduce quality loss. Common symptoms of senescence are excessive softening, tissue breakdown, diseases, loss of colour, loss of flavour, and off-flavours. Controlling respiration rate is the main way of controlling fruit shelf life. • The mango fruit continue to use oxygen and produce carbon dioxide after harvest, a process called respiration. • During respiration, heat is also produced. • Mango has a moderate respiration rate and undergoes a burst of respiration that coincides with the start of fruit ripening (called climacteric respiration, see Figure 2). • After reaching a peak, respiration falls again. • The rate of fruit deterioration relates largely to their respiration rate. Growth maturation mature ripening senescence Fruit development CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 4 • The higher the air temperature, the higher the respiration rate. • Control of temperature is crucial to minimising loss of quality because it slows down respiration and delays senescence. • There are other ways of slowing down respiration, for example by controlling the concentrations of oxygen and carbon dioxide. This is referred to as controlled atmosphere or modified atmosphere storage, but strict control of temperature is required for these practices to be effective. Figure 2. Respiratory patterns of fruit during ripening. 3.1.2 Ethylene production Ethylene is a natural plant hormone that is involved in plant growth, development, ripening and senescence. • Ethylene is a key component of ripening in climacteric fruit such as mango. In these fruit ethylene production rates increase during ripening, and added ethylene can stimulate ripening. • Ethylene in the air around produce can have both a positive and negative effect. o The positive effect is when ethylene is used to control the ripening of climacteric fruit, so that the ripening of the fruit is more predictable and makes marketing easier. o However if unwanted ethylene builds up in the air around sensitive produce, it can speed up ripening, so that the fruit ripen is too quickly and can spoil before being consumed. • Fruit ethylene production rates increases with higher air temperatures, fruit physical injuries (called wound ethylene), and rots. 3.1.3 Loss of water (transpiration) All plants lose water through a process called transpiration. • Transpiration continues after harvest. • It results not only in direct weight loss (reduces the saleable weight), but also reduces appearance and textural quality (shrivelling, softening, etc). Time CO2 output Heat output O2 Consumption Respiration rate Climacteric (ripening fruit) Eg. Mango Non-climacteric Eg. Orange CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 5 • Water loss increases with higher air temperatures, lower relative humidity of the air, more air movement across the fruit surface, and fruit surface injuries. 3.1.4 Fruit changes during ripening Ripening is the combination of processes involving changes in fruit quality attributes that leads to good eating quality. Both chemical and sensory qualities of the mango fruit change as they ripen (see Figure 3). The main changes are: • Texture: firmness decreases (softening of the flesh due to changes in the cell walls). • Colour: generally (depending on the cultivar) skin colour changes from green to yellow (mostly because of destruction of the green pigment), and the flesh from a pale yellow to a darker yellow. • Flavour: sugars increase (due to conversion of starch to sugars) and acidity decreases (due to breakdown of acids) in the flesh. Figure 3. Main changes in mango fruit during ripening. 3.2 Main causes of quality loss after harvest 3.2.1 Inadequate temperature control Temperature is the environmental factor that most affect the deterioration rate of fruit after harvest. • The higher the temperatures, the higher the respiration rate, ethylene production, transpiration, spore germination, and growth rate of pathogens. • The rate of deterioration of fruit typically increases 2-3 times for each increase of 10 oC above the optimum. 3.2.2 Mechanical damage • Can cause loss of appearance. Eating ripe Time R el at iv e ch an ge Firmness Skin colour Sugars Acidity CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 6 • Can also increase water loss, increase respiration and ethylene production, and allow entry of disease organisms. • Symptoms of mechanical injuries can appear externally (cuts etc) or internally (bruising and cracking of the flesh). • They may be visible almost as soon as they occur, or they may only become visible at some later time. • Injuries can occur at any stage of harvesting, packing, transport and marketing. The major types of mechanical injury are: Bruising • May not be obvious quickly, and only appear as an area susceptible to breakdown (discoloured) as the product is marketed. • Can be caused by impact or pressure damage. • Impact damage can occur from dropping of individual produce or packages, or from hard knocks on equipment and during transport. • Pressure damage can occur in product stacked too high or packed in a package unable to support the required weight. Abrasion injury (rubbing) • Leads to rupture of cells, loss of water, and cell death, resulting in dry black or brown areas on the surface. • May be visible immediately, but frequently takes several days to become visible. • Common causes are rubbing of produce against dirty or rough surfaces of containers and equipment, and rubbing of loosely packed produce during transport. Cracking and splitting • Caused by heavy impacts to hard products. • Can occur when a single fruit is dropped on to a hard surface, a container of fruit is dropped or loose fruit bounce against each other during transport. 3.2.3 Sapburn and skin browning Sapburn • Mango fruit spurt a highly caustic sap when the stem is first removed from the fruit (spurt sap), which causes severe injury to the fruit skin (dark spots, blotches or streaks around the stem end of the fruit and down the cheeks). • Sap is then released more slowly over about 1 hour (ooze sap), causing mild injury (light-brown discolouration to the skin). • The amount of sap exuded by fruit varies with cultivar, maturity (less mature fruit has more sap) and time of day (more sap in the morning). Skin browning CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Postharvest Physiology Training Manual Page 7 • Several different skin blemishes appear on mangoes during postharvest handling, causing brown markings on the skin (light- to dark-brown etching, staining, or spotting). • The damage can be similar to that caused by abrasion, brushing, or heat treatments for disease on insect control. • Possible causes include rough handling, fruit sitting in water and detergent, or sap left on the skin (from picking containers or equipment). Damage from sapburn and skin browning is not visible immediately and symptoms develop 1 to 2 days after injury. 3.2.4 Postharvest diseases and physiological disorders Diseases • The main problems in m