Techniques for Quality Control

Techniques for Quality Control

Techniques for Quality Control
Following procedures are followed for quality control of processed products:
  1. Identify the critical points in the process flow sheet which contributes to the major quality characteristics.
  2. Sample each critical point (batch or continuous operation) and identify what is being sampled and to what extent it is critical.
  3. Evaluate and relate quality at critical successive stages to costs and its application in field.
  4. Relate costs to deviation from specified levels.
  5. Evaluate data collected against standards and legal requirements.
  6. Provide consistent system for the orderly continuous evaluation of quality from the selection of raw material through different stages of processing.
  7. Diagnose problems and predict troubles before they occur.
  8. Determine the extent of drifts and shifts in production and minimize or localize deficiencies.
  9. Evolve a system to determine how well the quality control program is succeeding.

Quality control during processing
The sequence of operations in quality control followed during processing are as under:
  1. Raw material control
  2. Process control or the control of the manufacturing process
  3. Production and processing inspection
  4. Sensory evaluation
  5. Packaging
  6. Labeling and storage.

1) Raw material control: The quality of a food material is judged in terms of its nutritional value, purity, wholesomeness and palatability. If any of these properties is not optimal, the food quality is affected. Raw material examinations include test for genuineness and composition, freedom from contaminant, and conformity with official or factory standards.
The manufacturing of a desired food product depends upon the close collaboration between plant breeders, agronomists, horticulturists and food technologists. After all parameters of raw materials are met, a sample batch of raw materials is put through a trial run to get a preview of the end product. All control tests are run on the sample and any adjustments as required are made in the processed product. The equipment is examined for any sign of corrosion due to the acidity or alcohol content of the materials used. Approval for processing is given only after all quality specifications on the sample run have been met.

2) Process control: During processing, attention should be given to the processing procedure. In order to get the product of desired quality, all treatments standardized such as use of correct amount of ingredients, use of accurate method of preparation, mixing, processing time and temperature etc should be followed. The quality control tests should run continuously and concurrently with a 24-hr production schedule. The intermediary samples are taken for routine tests to establish that specific targets of quality are being achieved. The desired composition, consistency, colour and concentration are checked and ensured. Where processing controls are not properly employed e.g., during dehydration, the quality of the product may be seriously impaired. Satisfactory hygienic conditions are also maintained during processing, in order to protect the product from bacterial contamination.

3) Production, processing inspection: Examination of the finished product is carried out to determine as to what extent the desired quality specifications have been achieved. Careful inspection is made of the external conditions of the can. A can where both ends are concave is said to be ‘flat’ and is said to be good while the cans which have the problem of flipper, springer or smell do not pass inspection.
In case of canned products, a sample of the passed cans is opened and the contents are inspected. Where the product is dried, samples are examined for a blemish count. The dried product is regularly checked for its reconstitution value to enable the correct cooking instructions to be supplied on the package for the user.
Tests are also performed to check certain physical properties, such as crispiness, colour, viscosity and texture. Microbiological examinations are carried out to check whether proper hygienic procedures have been followed and whether the finished product is safe to eat or not.

4) Sensory evaluation: After physical, chemical and microbiological examination have been performed on a finished product with a satisfactory result, the product is considered ready for distribution, but only after its sensory quality has been assessed. To the processor, a palatable product ensures sales because palatability attracts consumers and to the consumer, palatability satisfies his gustatory senses.

5) Packaging: The primary purpose of manufacture is to produce a food product, to keep it in good condition and to preserve the flavour until it reaches the consumer. Therefore, it is essential that a suitable packaging material is chosen for packing a finished product. The material used for packaging must not contaminate the product and must be effective in preventing the product from deterioration. A variety of containers have also been designed to handle products that are sensitive to light, temperature, oxygen, moisture and contact with the chemicals.

6) Labeling and storage: After packing, labels are pasted on the finished products which are intended for sale. The information on the label shall include name of product, ingredients used, date of manufacture, name and address of the manufacturer, sale price, net weight or volume etc. A good and an attractive label is an aid to the successful marketing of the product. The product should be stored in a cool and dry place.

Critical control points of inspection
The critical control points of inspection followed during canning of foods in syrup are as under:

1. Raw material: The important material used is fruit sugar and citric acid. Water used in making syrup should be suitable for purpose of canning.
  • Fruit: Variety, maturity, extent of spoilage or damage, pesticide residues, deterioration in handling and storage, potential contamination etc.
  • Sugar and citric acid with respect to physical and chemical characteristics.
2. Tin containers
  • Type of tin plate, weight of tin coating, side seam, and double seam accuracy.
3. Washing of fruits
  • Quality of water
4. Preparation of fruit
  • Efficiency of preparatory operations like peeling, slicing, coring, trimming and freedom from damaged or diseased portion.
  • Uniformity with respect to colour, texture and maturity.
5. Preparation of syrup
  • Calculation of strength of covering syrup required in relation to total soluble solids in fruit, filled weight of slices, weight of covering syrup added and cut-out degree brix required in the finished product.
  • Control of weight, temperature and uniformity of strength at the time of filling.
6. Filling: The coefficient of variation in the weight of empty cans is generally about 4%. The fill-in-weight of fruit required to get the desired drained weight in the canned product should be carefully determined.

7. Exhausting: Periodic checks should be made to ensure that the cans coming out of the exhaust box have attained the desired can centre temperature. It has direct relation to ultimate vacuum and is related to shelf life and behavior at different altitudes.

8. Container closure operation
  • Protection of empty containers
  • Cleaning of containers before filling
  • Maintenance of can seamers
  • Measurement of can seams
9. Processing
  • According to good manufacturing practices
  • Pasting of process schedules near retorts
  • Recording of retorting operation
10. Cooling Water
  • Microbiological quality
  • Chlorine content
11. Post process handling
  • Prevention of filled containers from damage and contamination
  • Cooling
  • Warehousing-temperature, humidity etc.
12. Clean up and sanitation

13. Steam quality

14. Examination of finished product

15. Sanitation control
  • Sampling
  • Location
  • Visual appearance
  • Microbiological level
  • Rating-good, fair or poor.
16. General inspection
  • Raw material receiving department
  • Product preparation area
  • Packing and dispatching area
  • Windows, doors, wall surfaces, floor etc.
Similarly, critical control points (CCP) for other processed products can be worked out.
Last modified: Sunday, 4 March 2012, 10:29 AM