Postharvest Technology PDF

INTRODUCTIO N BWD 21402 Postharvest Technology By: Shahidah Md Nor, PhD 1.1 Postharvest system The moment a produce is uprooted from the ground, or separated from the parent plant, it begins to deteriorate. To halt deterioration process is impossible, so the only alternative we have is to slow dow...

INTRODUCTIO N BWD 21402 Postharvest Technology By: Shahidah Md Nor, PhD 1.1 Postharvest system The moment a produce is uprooted from the ground, or separated from the parent plant, it begins to deteriorate. To halt deterioration process is impossible, so the only alternative we have is to slow down the progression. In agriculture, postharvest is the last stage of crop production that spans from harvesting until the produce is being utilised by consumers Food supply chain In the food supply chain, food moves from producer to consumer via the processes of production, processing, distribution, retailing and consumption; thus, food moves from farmer to consumer in a domino‐like fashion. At the same time, money that consumers pay for food moves from consumers to producers in the reverse process, again in a domino‐like fashion from consumer to retailer to distributor to processor to farmer. Thus, the two‐sided causality that connects farmers and consumers is mediated by these two sets of domino causalities. The post-harvest system should be thought of as encompassing the delivery of a crop from the time and place of harvest to the time and place of consumption, with minimum loss, maximum efficiency and maximum return for all involved (FAO, 2022).  The primary role of an effective post-harvest handling system is ensuring that the harvested product reaches the consumer, while fulfilling market/consumer expectations in terms of volume, quality, and other product and transaction attributes, including nutrition, food security, and product safety. The post-harvest system encompasses a sequence of activities and operations that can be divided into two groups: Technical activities: harvesting, field drying, threshing, cleaning, additional drying, storage, processing. Economic activities: transporting, marketing, quality control, nutrition, extension, information and communication, administration and management.  Post-harvest handling refers to the various practices involved in the handling, storage, and transportation of agricultural products after they have been harvested from the farm. It is a critical step in the food supply chain as it helps to ensure that food products are safe, fresh, and of good quality by preventing spoilage, minimizing losses, and extending the shelf life of the products. Main elements of the post- harvest system Sorting- Sorting is done by hand/ machine to remove the fruits and vegetables which are unsuitable to market or storage due to damage by mechanical injuries, insects, diseases, immature, over-mature, misshapen etc. This is usually carried out manually and done before washing Main elements of the post-harvest system Infield handling Good agricultural practices usually cover pre-harvest practices, while good handling practices deal with postharvest practices for fruits and vegetables. Main elements of the post-harvest system Trimming: Trimming is done in crops like cabbage and lettuce etc. To remove unwanted, discoloured, rotten and damaged parts. Trimming enhances visual quality, reduces deterioration of produce, facilitates handling packaging and transport. Main elements of the post- harvest system
Harvesting - Process of gathering crops or other agricultural products from the field. It is an important step in agriculture as it marks the end of the growing season and the beginning of the post-harvest period Washing/rinsing is done manually under tap water or in a wash tank using soft muslin cloth. Produce should be thoroughly washed with clean water (preferably with 100 – 150 ppm hypochlorite/chlorine) or soap or calcium hydroxide. Most efficient detergent used is sodium meta bisulphate. Main elements of the post-harvest system Post-harvest drying. process of reducing the moisture content of harvested crops. Post-harvest drying is typically done using artificial means such as fans, heaters, or dehumidifiers, and the goal is to reduce the moisture content of the crop to a level that is safe for storage and transportation. The purpose of post-harvest drying is to prevent spoilage, reduce the risk of mold and bacterial growth, and improve the shelf life of the harvested crop. Post-harvest drying can also be used to produce value- added products such as dried fruits and vegetables. Main elements of the post-harvest system Grading of fruits and vegetables is generally done on the basis of physical characteristics like weight, size, colour, shape, specific gravity, and freedom from diseases. For fresh marketing, the known methods of grading of fruits and vegetables are manual grading, or machine grading,  Main elements of the post-harvest system Transport- Transport plays a critical role in post-harvest systems as it is responsible for moving harvested crops from the field to storage, processing, or market destination Main elements of the post-harvest system Threshing -post-harvest operation that involves separating the grain from the straw or chaff of cereal crops such as rice, wheat, and maize. Threshing does not remove the bran from the grain. Main elements of the post-harvest system Storage- It is the link between the time of harvest and the time of consumption or processing. The primary role of storage in the post-harvest system is to preserve the quality and quantity of harvested crops for future use. Facilities, hygiene and monitoring must all be adequate for effective, long-term storage. In closed structures (granaries, warehouses, hermetic bins), control of cleanliness, temperature and humidity is particularly important. Main elements of the post-harvest system Packaging –Incorrect packaging can accelerate spoilage. Packaging can serve to protect against contamination, damage and most importantly moisture loss. Main elements of the post-harvest system Marketing. Marketing is the final and decisive element in the post- harvest system, although it can occur at various points in the agro-food chain, particularly at some stage in processing. Moreover, it cannot be separated from transport, which is an essential link in the system.  Table 1. Comparison between properties of cereals and roots and tubers regarding their storage capacity (Source: FAO, 2023) Non-perishable food crops Perishable food crops Harvest manly seasonal, need for storage of long Possibility of permanent or semi-permanent production, duration needs for short-term storage Preliminary treatment (except threshing) of the crop Processing in dried products as an alternative of the before storage exceptional shortage of fresh products Products with low level of moisture content (10-15 Products with high level of moisture in general between percent or even less) 50-80 percent Small "fruits" of less than 1 g Voluminous and heavy fruits from 5 g to 5 kg or even more Respiratory activity very low of the stored product, heat High or even very high respiratory activity of stored limited products inducing a heat emission in particular in tropical climates Hard tissues, good protection against injuries Soft tissues, highly vulnerable Good natural disposition for storage even for several Products easily perishable, natural disposition for years storage between some weeks up to several months (strong influence of the varieties) Losses during storage mainly due to exogenous factors Losses due partly to endogenous factors (respiration, (moisture, insects or rodents) transpiration, germination) and partly to exogenous factors (rot, insects) 1.2 Postharvest food losses and food waste Postharvest loss can be defined as the degradation in both quantity and quality of a food production from harvest to consumption Quality losses include those that affect the nutrient/caloric composition, the acceptability, and the edibility of a given product. These losses are generally more common in developed countries Quantity losses refer to those that result in the loss of the amount of a product. Loss of quantity is more common in developing countries. A recent.FAO report indicates that at global level, volumes of lost and wasted food in high income regions are higher in downstream phases of the food chain, but just the opposite in low-income regions where more food is lost and wasted in upstream phases. Quality losses vs Quantity loss Qualitative losses of the products, such as loss in edibility, nutritional quality, caloric value and consumer acceptability, are much more difficult to assess than quantitative losses. Standards of quality, consumer preferences and purchasing power vary greatly between countries, people and cultures. For example, elimination of defects from a given commodity before marketing is much less rigorous in developing countries than in developed countries. Food waste is a subset of postharvest food losses and is the loss of edible food due to human action or inaction, such as throwing away produce, not consuming available food before its expiry date or taking serving sizes beyond one’s ability. The Food and Agricultural Organization (FAO) estimates that the value of post-harvest loss in Sub-Saharan Africa is about US $4 billion a year out of an annual grain crop value of US$27 billion produced in the years 2005-2007. Increasing Production versus Reducing Postharvest Food Losses
Food production is currently facing the challenges of limited land and water and increased weather variability due to climate change. Food production alone will not ensure that more food can be put into the mouths of the people To sustainably achieve the goals of food security, food availability also needs to be increased through reductions in post-harvest losses at the farm, retail and consumer levels. When the food pipeline is repaired through appropriate postharvest technologies, more food will be made available for consumption by the consumers. Figure 2: Factors contributing to postharvest losses of fruits and vegetables in Malaysia (Azizah et al., 2009) Post-harvest losses are generally higher at the wholesale to retail stage (pasar malam) than the farm to wholesale stage