Processing of Horticultural Crops (1+2)

Quality Standards

Introduction
Quality is a measure of the degree of excellence or degree of acceptability by the consumer. It is also defined as the combination of attributes or characteristics of the products that has significance in determining the degree of acceptability of the product to a user. Industry defines quality as the measure of purity, strength, flavour, colour, size, maturity, workmanship or any other distinctive attribute or characteristics of the product. The quality standards of fresh and processed fruit or vegetable products vary with their intended use. For marketing purposes; size, attractiveness, maturity, organoleptic quality and freedom from defects are to be kept in mind. While for processing, physico-chemical attributes of raw material such as presence of soluble solids, development of uniform colour, flavour, juiciness, uniform maturity, tenderness in some vegetables etc are taken into consideration. During processing of fruit or vegetables into value added products; colour, flavour and texture etc also become important.

Quality standards: Common standards used for measuring product quality are:

1. Legal standards
2. Voluntary standards
3. Industry standards
4. Consumer oriented or Grade standards

1. Legal standards: These are the standards commonly established by the central or state or local agencies like corporation, municipal committees etc and are usually mandatory. These mandatory standards are established by law or through regulations for maintaining quality. Legal standards are generally concerned with freedom from adulteration and mostly include insects, moulds, yeasts, residual pesticides and maximum limits of additives allowed or established specific condition in processing so that foods are not contaminated with extraneous matter. Examples of legal standards include Food Safety and Standards Act, 2006 (FSSA), Food Safety and Standards Rules, 2011 and Food Safety and Standards Regulations, Food and Drug Administration Act (FDA) etc. Minimum standards of quality for establishment of unit, labeling and packaging, and physico-chemical attributes for different food products are specified under FSSA, (2006) and Food Safety and Standards Regulations, (2011) which arte mandatory to be followed for any food business operations.

2. Voluntary standards: These represent the standards recommended by various segments of the food industry. Company standards generally represent the consumer image and may become trade mark or symbol of product quality. Mostly these standards are used by private firms and tend to vary depending upon the organization. Companies like pepsi, kissan and coca cola, etc sets their own standards for different products.

3. Industrial standards: These are the standards where an organized group attempts to establish certain limits of quality for any given commodity. Generally these become effective by pressure from marketing organization for specific commodities, where the legal standards are not involved.

4. Consumer oriented or grade standards: These standards represent the consumer requirement of particular product and are based on experience. For example few consumers do not prefer a product with preservatives.

Methods for determining quality

A. Objective methods
B. Subjective methods

A. Objective methods: Objective methods of quality evaluation are based on observation from which the attitude of investigator is entirely excluded. They are based on recognized standards, scientific tests and are applicable to any sample of the product without regard to its previous history or ultimate aim. They represent the modern ideas in quality control because the human element is completely excluded.

Objectives methods are of three types i.e., Physical methods;, chemical methods and microscopic methods.

1. Physical methods: These are the quicker methods and require least training for the evaluator. They include visual appearance, colour, texture, consistency, size, shape or some process variables like head space, fill, vacuum, drain weight etc. The colour of the food products can be measured using calorimeter, tintometer or Hunter colour difference meter. While texture can be determined by using texture analyser or firmness of fruit is estimated by penetrometer. On the basis of texture profile, the product can be classified as chewy, grainy, crispy, mealy etc. These methods are called as instrumental methods. Detail of common method used in fresh and processed products is shown in Table 16.1.

2. Chemical methods: These are the standard analytical methods and are used for quantitative chemical evaluation of nutritive value and quality levels. However, such analytical methods are lengthy, tedious and expensive. For routine analyses quick tests are developed like pH, acidity, TSS, jellification etc. Detail of some method used in fruit products is shown in Table 16.1.

3. Microscopic methods: They are also called as microbiological methods. They are used extensively in quality control programmes but require considerable training for proper interpretation of results. Two types of microscopic methods are:

a) To check adulteration and contamination of product with mould, yeast, bacteria, insect excreta etc.
b) Differentiate between cell type, tissue type and identification of micro-organisms in fresh and processed products.

B. Subjective method: In subjective method, the quality evaluation is based on the opinion of the investigator. It is usually a physiological reaction which is a result of past experience, training, individual preference and power of perception. These methods are subjective because an individual is required to give his opinion for quantitative and qualitative value of characteristics. These methods involve the use of sense organs and are thus called as sensory methods. Sensory perception includes colour, flavour, odour, taste, touch etc. The food is selected by making use of all physical senses like sense of sight, touch, smell, taste and even hearing. The snap of chip, crackle of a breakfast cereal, crunch of apple or celery are textural characters. Other senses are eyes, fingers, tongue, nose and ears. A guide to common methods for sensory evaluation is given in Table 16.1.

Table 16.1: Common physical, chemical and microbiological and sensory methods for fresh and processed fruit, vegetable products

Attribute	Method /equipment to be used
1. Physical test Size Weight Volume Specific gravity Gross weight Tare weight Net weight Drain weight Colour Texture Firmness Consistency Viscosity Head space Vaccum/ pressure Seam measurement Can testing	Vernier calliper Weighing balance Water displacement method Specific gravity bottle, pycnometer Net weight + Tare weight Weight of container Gross weight – Tare weight Net weight – weight of syrup/ brine Visual/ colour charts Texture Analyser Penetrometer, Pressure tester Ostwald viscometer Brookfield viscometer Head space gauge Vaccum/ pressure gauge Seam checking gauge/ seam micrometer Can tester
2. Chemical test Total soluble solids Brine strength Moisture Total solids pH Titratable acidity Sugars (Reducing, Non-reducing & total sugars) Ascorbic acid Salt Sulphur dioxide Ash Benzoic acid	Hand refractrometer, Abbe refractrometer, Hydrometer Salometer Oven drying method, infra-red moisture meter   -do- pH meter Alkali titration method Lane and Eynon method 2,6 dichloro-phenol- indophenol dye titration method Silver nitrate titration using Mohr’s method Modified Ripper-titration method Muffle furnace Benzoic acid is converted to water soluble sodium benzoate. Acidification of sodium benzoate to form water insoluble benzoic acid and chloroform. Removal of chloroform with evaporation. Dissolving residue containing benzoic acid in alcohol and titrate with standard alkali.
3.Microbiological tests Total plate count/ viable count Yeast and moulds count Coliform test Extraneous contamination Insect fragments	Inoculation chamber, incubator Howard’s mould counting method Presumptive test, conferred test, completed test Macroscopic/microscopic examination Wildman trap flask
4. Sensory evaluation Colour Flavour Body Overall acceptability	Hedonic rating test Numerical scoring test Ranking test Paired comparison test; Single sample test; Multiple sample test

Objective of quality control

1. Control over raw materials by setting up specifications
2. Improvement of product quality
3. Improvement in processing methods by reducing cost of production and improving profits
4. Standardization of the finished product according to label specifications
5. Maintenance of sanitary conditions in the plant
6. Greater consumer confidence towards quality of the product

Factors affecting quality
Quality of processed fruit and vegetables is affected by the following basic factors, either individually or in combination.

(1) Cultivar: It is an important factor for producing quality product. The varieties/cultivars differ in size, shape, colour and chemical composition. High yield, attractive appearance and good shipping and keeping quality are the important characters taken in to consideration.

(2) Cultural practices: These include organic matter, moisture, fertilizer, method of cultivation, irrigation and pest control methods. Any of these factors may be the limiting factor in producing a quality processed product. The best example of a limiting quality factor is the use of insecticides that give good control of the pests, but produce or leave a residue.

(3) Maturity: The maturity of fresh produce is more important than the specific cultivar in many cases. Any recommended fruit or vegetable cultivar for processing should mature uniformly, should be resistant to insects and diseases. The crop harvested at its optimum condition need to be processed promptly otherwise the quality may drop down into the next lower grade in just a few hours.

(4) Harvesting and handling: Harvesting and handling methods of fresh fruit and vegetables go hand in hand with maturity and other quality characteristics. The fruit or vegetable should be harvested at the desired stage of maturity and should be delivered to the processing plant immediately to preserve the quality. Important post harvest factors affecting quality of the produce are given in Table-16.2.

Table-16.2: Post harvest factors affecting quality of fruit and vegetables.

Post harvest factors	Quality affected
1. Temperature	Off flavour, weight loss and wilting in leafy vegetable and reduces vitamin C content. Reduces the appearance of fruit by checking the carotenoid development.
2. Heat of respiration	Deteriorates the quality and speed up the growth of micro-organisms during storage.
3.Cleaning & washing	Cleaning (fruits) and washing (root vegetables) remove dirt and spray residue and provide good appearance
4. Grading	Processed product must be graded to maintain uniformity in size, shape and quality
5. Chemical treatment	Treatment with ethaphon and alar increases colour and reduces astringency.
6. Pre-cooling	Reduces weight loss and maintain freshness and appearance
7. Hot water treatment	Provides protection against diseases e.g. anthracnose in mango

(5) Processing: The important factors that must be carefully controlled during the processing of fruits and vegetables include efficiency of washing, trimming, cutting, inspecting and sorting, time and temperature of blanch or scald, fill weights, brine or syrup characteristics, closing machine vacuums, can seam formation and processing time (cooking and cooling times