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Post-Harvest Quality of Horticultural Produce

Explore key factors, quality parameters, evaluation methods, and treatments to maintain and enhance the post-harvest quality of fruits, vegetables, flowers, and processed commodities for better market value and consumer acceptance.

Food◦
Post-harvest quality of fruits, vegetables, flowers and various processed commodities Prepared by Umesh Timilsina Assistant Professor CNRM, Bardibas Agriculture and Forestry University
Post-harvest quality of fruits, vegetables, flowers and various processed commodities • Post-harvest quality is one of the most important aspects of horticultural science because it determines the market value, consumer acceptance, storage life, processing suitability, and export potential of horticultural produce. • The quality of fruits, vegetables, flowers, and processed products begins in the field and must be maintained throughout harvesting, handling, storage, transportation, processing, and marketing. • High-quality produce is characterized by desirable appearance, freshness, nutritional value, safety, and freedom from defects.
• Post-harvest quality is the combination of physical, chemical, physiological, nutritional, microbiological, and sensory characteristics of harvested horticultural produce that determine its suitability for consumption, processing, storage, and marketing. Importance of Post-harvest Quality • Increases consumer acceptance. • Enhances market value. • Extends shelf life. • Reduces post-harvest losses. • Improves export opportunities. • Ensures food safety. • Increases farmers' income. • Provides better raw materials for processing industries.
Quality of fresh produce includes •Appearance (size, shape, colour, gloss and freedom from defects and decay •Texture (firmness, crispness, juiciness, toughness), flavour, sweetness, sourness (acidity), astringency, aroma and of flavours. •Nutritive value (Vitamins, minerals, dietary fibre, phytonutrients) •Quality should be described by consumers need and wants.
Quality Parameters and Specifications • Quality parameters are measurable characteristics used to assess the acceptability of horticultural produce. A. External Quality Parameters Parameter Description Size Uniform and appropriate size Shape Characteristic shape of the variety Colour Uniform natural colour Freshness Bright, turgid appearance Firmness Suitable texture Freedom from defects No bruises, cracks, insect damage, or diseases Surface cleanliness Free from dust and contaminants Uniformity Similar size and maturity within the package
B. Internal Quality Parameters Parameter Description Total Soluble Solids (TSS) Indicates sweetness (°Brix) Acidity Contributes to flavor Sugar content Determines sweetness Sugar-acid ratio Overall eating quality Vitamin C Nutritional quality Dry matter Processing suitability Juice content Important in citrus fruits Aroma and flavor Consumer preference
C. Nutritional Quality Parameters • Vitamin C • Vitamin A • Antioxidants • Minerals • Dietary fiber • Phenolic compounds • Lycopene (Tomato) • Anthocyanins (grapes, berries) D. Safety Quality Parameters • Free from pesticide residues • No heavy metal contamination • Free from harmful microorganisms • Free from mycotoxins • Safe for human consumption
E. Flower Quality Parameters Parameter Importance Flower size Market value Colour Consumer preference Stem length Floriculture standards Stem strength Ease of handling Freshness Longer vase life Number of buds Quality grading Vase life Consumer satisfaction
F. Processed Commodity Quality Parameters • Examples include jams, jellies, juices, pickles, dehydrated products, frozen vegetables, canned fruits, and dried flowers. • Important parameters include: Colour retention Texture Flavor Aroma Nutritional value Packaging quality Shelf life Microbial safety
Quality Specifications • Quality specifications are standards established for grading and marketing produce. Common Specifications • Uniform size • Characteristic colour • Proper maturity • Freedom from diseases • Freedom from insect damage • Clean surface • Good firmness • Acceptable TSS • Proper packaging • Appropriate labeling
Factors Responsible for Quality A. Pre-harvest Factors 1. Variety (Genotype) • Different varieties have different quality characteristics. Examples: • Alphonso mango has excellent flavour. • Red Lady papaya has attractive flesh colour. 2. Climate • Temperature • Rainfall • Relative humidity • Light intensity • Wind • These influence sugar accumulation, colour, and fruit development. 3. Soil Fertility Soil pH Organic matter Drainage 4. Nutrition • Balanced nutrition improves: Fruit size Colour Firmness Shelf life Nutritional quality
5. Irrigation • Proper irrigation improves: • Fruit development • Juice content • Texture • Shelf life 6. Pest and Disease Management • Healthy crops produce higher-quality fruits, vegetables, and flowers. 7. Plant Growth Regulators • Examples: • NAA • GA₃ • Salicylic acid • These may improve fruit quality, size, firmness, and shelf life when used appropriately.
B. Harvest Factors Harvest maturity Harvesting method Time of harvesting Weather during harvest Mechanical injury C. Post-harvest Factors Washing Sorting Grading Pre-cooling Packaging Storage temperature Relative humidity Transportation Marketing practices
Factors influencing Postharvest quality 1. Variety: • Different varieties have got their own characteristics quality. 2. Growing condition • External environment, temperature, rain, shade, wind, sunshine 3. Soil and nutrition • Many physiological disorder and deficiency symptoms 4. Chemical treatment and application of pesticides 5. Harvesting: Harvesting at proper stage of maturity 6. Harvesting method: E.g.; Mechanical damage 7. Length and method of storage 8. Post harvest treatment: Curing, Chemical treatment, radiation
Evaluation of Quality • Quality evaluation involves assessing physical, chemical, sensory, and microbiological characteristics. A. Physical Evaluation • Measured parameters: Parameter Instrument Fruit weight Digital balance Fruit size Vernier caliper Fruit length Measuring scale Firmness Penetrometer Colour Colorimeter or visual chart
B. Chemical Evaluation Parameter Method TSS Hand refractometer Acidity Titration Vitamin C 2,6-Dichlorophenolindophenol (DCPIP) titration Total sugar Lane and Eynon method Moisture Oven drying pH Digital pH meter
C. Sensory Evaluation • Sensory analysis is conducted by trained panelists or consumers. • Parameters include: Appearance Colour Aroma Taste Texture Overall acceptability • Common evaluation scales: 5-point hedonic scale 9-point hedonic scale D. Microbiological Evaluation • Total microbial count • Yeast count • Mold count • Coliform count • Pathogen detection
Post-harvest Treatments to Control Quality A. Pre-cooling Purpose • Removes field heat. • Reduces respiration. • Delays deterioration. • Maintains freshness. B. Cold Storage • Maintains: • Firmness • Freshness • Nutritional quality • Shelf life
C. Controlled Atmosphere (CA) Storage Principle • Maintains low oxygen and elevated carbon dioxide concentrations. Benefits • Slows respiration. • Delays ripening. • Reduces decay. • Extends storage life. D. Modified Atmosphere Packaging (MAP) Benefits • Reduces respiration. • Delays senescence. • Maintains colour and texture. • Extends shelf life.
E. Waxing • Benefits: • Reduces moisture loss. • Improves appearance. • Delays shriveling. F. Edible Coatings • Common coatings: Chitosan Aloe vera gel Carnauba wax Beeswax Starch-based coatings Advantages: • Reduces water loss. • Delays ripening. • Reduces microbial growth. • Improves shelf life.
G. Chemical Treatments Common chemicals: Chemical Purpose Calcium chloride Improves firmness Salicylic acid Delays ripening Ascorbic acid Reduces browning Citric acid Antioxidant Potassium permanganate Ethylene absorber 1-Methylcyclopropene (1-MCP) Delays ethylene action
H. Heat Treatments Examples: • Hot water treatment • Hot air treatment • Purpose: • Disease control • Insect control • Delay ripening I. Irradiation Benefits: • Controls insect pests. • Reduces microbial load. • Delays ripening. • Extends shelf life.
Quality Evaluation of Important Horticultural Crops Crop Important Quality Parameters Mango Colour, TSS, firmness, flavour Banana Peel colour, sweetness, firmness Papaya Flesh colour, TSS, firmness Apple Colour, firmness, acidity Tomato Colour, firmness, lycopene, TSS Potato Dry matter, size, freedom from greening Onion Neck dryness, bulb firmness Rose Stem length, bud size, vase life Gladiolus Spike length, number of florets
Quality Evaluation of Processed Commodities Product Important Parameters Jam TSS, colour, spreadability Jelly Clarity, gel strength Juice TSS, acidity, flavour Pickle Texture, flavour, acidity Dried fruits Moisture content, colour Frozen vegetables Colour, texture, nutrient retention Canned fruits Colour, flavour, microbial safety
Quality test/ Sensory evaluation/ Organoleptic test • An organoleptic test is a sensory evaluation method used to assess the qualities of food and other products based on the senses of taste, sight, smell, touch, and sometimes sound. • This type of testing is crucial in food science, product development, quality control, and consumer research. Importance: • Organoleptic tests are crucial for ensuring the sensory qualities of products meet consumer expectations and industry standards. • They provide valuable insights into product attributes that cannot be measured by chemical or physical tests alone.
• Many fruits and vegetables have specific taste. The composition of fruits and vegetables can be analysed by some instruments or chemical tests. • Example: Total soluble Solids (TSS): Refractometer Titratible Acidity (TA): Titration method Vitamins, lycopene, chlorophyll, carotene: Chemical reaction method • The acceptability of a commodity or its product is evaluated by taste panel. • It is done by different individuals on the basis of organoleptic test or visual observation. Hedonic scale of 1 to 5 or 1 to 9 or any other can be used. • Bhattarai (2005) used the hedonic scale of 1-6 point scale for the color of tomato. Thompson used the hedonic point scale of 1-12 for the same. • Acceptability can be evaluated by using 1-9 hedonic scale (Bhattarai, 2005). • For example: 1 - 2 - 3 - 4 - 5 - 6 - 7 – 8 - 9 Less acceptable High Acceptable
Consideration during Organoleptic Test • While doing organoleptic test, the following things should be taken into consideration The person should be in acquaintance with the quality of product. The person should not be taste blind. The person should not be hungry or just have enough food. The room should be neat and clean, there should not be smell and flavour. There should be enough light in the room. There should not be any disturbance and pollution. It should be done in a quiet, clean and calm place. Mouth should be rinsed with water after each taste.
Factors Responsible for Quality Deterioration • High respiration • Moisture loss • Ethylene production • Mechanical injury • Improper storage temperature • High humidity • Microbial infection • Poor packaging • Delayed marketing • Improper handling
Methods to Maintain High Post-harvest Quality • Harvest at the proper maturity stage. • Handle produce carefully. • Pre-cool immediately after harvest. • Wash with clean, sanitized water. • Grade and sort produce. • Use suitable packaging materials. • Maintain the cold chain. • Apply approved post-harvest treatments. • Store at recommended temperature and relative humidity. • Transport under hygienic conditions.
Summary Table Quality Aspect Examples Physical Size, shape, colour, firmness Chemical TSS, acidity, sugar, Vitamin C Nutritional Vitamins, minerals, antioxidants Sensory Taste, aroma, texture Microbiological Safe microbial limits Safety Residue-free, contaminant-free
Key Points • Post-harvest quality refers to the combined physical, chemical, nutritional, sensory, microbiological, and safety attributes of horticultural produce that determine its acceptability for consumption, processing, storage, and marketing. • Major quality parameters include size, shape, colour, firmness, TSS, acidity, sugar content, vitamin C, aroma, texture, and freedom from defects. • Quality specifications require produce to be uniform, mature, clean, free from pests and diseases, and properly packaged. • Quality is influenced by pre-harvest factors (variety, climate, soil, nutrition, irrigation, pest management), harvest factors (maturity, harvesting method, weather), and post-harvest factors (handling, storage, packaging, transportation).
• Quality evaluation involves physical measurements, chemical analyses, sensory assessment, and microbiological testing. • Major post-harvest treatments for maintaining quality include pre- cooling, cold storage, controlled atmosphere storage, modified atmosphere packaging, waxing, edible coatings, calcium and antioxidant treatments, hot water treatment, and irradiation. • Maintaining the cold chain, minimizing mechanical injury, practicing proper sanitation, and using appropriate packaging are essential for preserving the quality of fruits, vegetables, flowers, and processed horticultural commodities throughout storage and marketing.