QUALITY CONTROL IN THE FOOD PROCESSING BUSINESS
Introduction
Quality control (QC) is not an optional extra in food processing; neither is it something done only by large manufacturers. It is an essential component of any food processing business. Th e purposes of quality control are: To protect the customers from dangers (eg contaminated foods) and ensure that they get the weight and quality of food that they pay for. To protect the business from cheating by suppliers, damage to equipment (eg stones in raw materials) and false accusations by middlemen, customers or suppliers. To be sure that food laws operating in a country are complied with. Quality control need not be time consuming or expensive, and the results of quality control tests should help save money in the long run. In general, quality control procedures should be as simple as possible and only give the required amount of information. Too little information means the test has not done its job; too much information and management decisions may be delayed or confused. Quality control is used to predict and control the quality of processed foods. It is no use producing a food, testing it to find the quality, and then trying to find a buyer for that particular batch of food. Quality control is used to predict the quality of the processed food and then control the process so that the expected quality is achieved for every batch. This means that quality specifications must be written and agreed with suppliers or sellers , and control points must be identified in the process.
Quality specifications
The quality of foods or ingredients can be measured in different ways but one popular method is to describe 'quality attributes', as in Table 1. A specification can then be written and agreed with the supplier or seller, which lists the quality attributes that are required in a food. An example of a quality specification for tomatoes to be used for processing into paste is shown in Table 1.
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Attribute Colour Size Shape Damage - splitting - insect - mould Hardness
Accept Orange/red Any Any
Reject More than 10% green -
Less than 5% Less than 5% None Soft to over-soft
More than 5% More than 5% Any evidence of mould More than 10% hard
Table 1: Quality attributes for tomatoes used for tomato paste. A number of points arise from such a specification: A representative sample of the food must be tested to make sure the whole batch meets the specification. (For small batches it might be possible to examine every item.) The size of sample needed for testing can be calculated, but this is fairly complex, and usually unnecessary for a smallscale business. The percentage of substandard items which cause a batch to fail the test can be increased or decreased depending on how reliable the supplier is, or how important the particular attribute is to the seller/manufacturer. Some attributes may need to be tested with equipment in order to avoid arguments over interpretation. In Figure 1, for example, the hardness could be tested with a simple 'penetrometer' to define what is 'hard' and what is 'soft'.
Figure 1: Fruit hardness test using a penetrometer.
The size and shape of the tomatoes is not important because they are to be crushed to a pulp. In other examples (such as fruit for bottling) the size might be important. The ripeness and flavour of the tomatoes - assessed by colour and hardness -, and damage caused by poor storage and handling, are very important: the specification concentrates on these. Each specification takes account of the intended use of the products and the most likely important faults that could be expected.
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Quality attribute
Quantitative Hidden Harmful substances Microbiological Nutritive value Additives Sensory Colour Size, shape (appearance) Thickness or texture Taste Flavour
Example
Required sugar content of fruit (eg 15%)
Aflatoxin in groundnuts Number of bacteria in a food Vitamin content of a food Artificial flavours, thickeners etc
Ripeness of fruit Size of chopped food, particle size of flour Juice consistency, toughness of meat Saltiness, sweetness, sourness and bitterness Characteristic flavour of tomato
Control points
In every food process there are particular stages which affect th e quality of the final product. For example, the amount of heating given to pasteurised juices affects their colour, flavour and storage life; in sausage making, the amount and type of grinding affects the texture of the meat. Such stages are identified as control points, and quality control checks are made at these points in order to control the process. Manufacturers therefore need first to identify the control points in their process - using outside technical assistance if necessary - and then to set up a specification for operators to use. For example, in jam making, the amount of pectin, fruit and sugar should be carefully controlled : therefore, the weighing of ingredients is a control point, as the weights of each ingredient must be specified and carefully weighed out. In the same way, other control points would be: the acidity of the jam, the sugar content after boiling and the temperature of filling. The mix should be checked for correct acidity, the sugar content checked during boiling (using a thermometer or refractometer), and the temperature checked before filling (using a thermometer). Checks at control points can therefore be used to control the process and to ensure that each batch of product is of similar quality.
References and further reading
Quality Assurance/Control in Food Processing. Contained in: Food Fortification - Technology
and Quality Control. (FAO Food and Nutrition Paper - 60) Fruit and vegetable processing: Chapter 10 - Quality control/quality assurance and international trade; good manufacturing practices (gmp); hygiene requirements; hazard analysis and critical control points (haccp)
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Quality and process control in the food industry Pearl Adu-Amankwa. Food Research Institute, P.O. Box M.20, Accra. Published in The Ghana Engineer, May 1999 Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) and Agreement on Technical Barriers to Trade (TBT). Module 7 - National Food Control Systems: Components and Operation. Food Quality and Standards Service. Food and Nutrition
Division, FAO.
Food Hygiene Training: A Guide to its Responsible Management Institute of Food Science
and Technology 1992
Making Safe Food: A guide to Safe Food Handling and Packaging for Small -scale Producers
Peter Fellows et al, Practical Action Publishing 1998 Food Poisoning & Its Prevention Technical Brief, Practical Action Quality Assurance for Small-scale Rural Food Industries FAO Agricultural Service Bulletin 117, Food and Agriculture Organization of the United Nations 1995 Starting a Small Food Processing Enterprise by Peter Fellows, Ernesto Franco & Walter Rios Practical Action Publishing/CTA 1996 Food Packaging a selection of Practical Action Technical Briefs Appropriate Food Packaging by Peter Fellows & Barry Axtell, Practical Action Publishing ILO/TOOL 1993 Packaging UNIFEM Practical Action Publishing 1996 Small-scale Food Processing: A guide to appropriate equipment , Edited by Peter Fellows & Ann Hampton, Practical Action Publishing/CTA 1992 Small-scale Food Processing: A Directory of Equipment and Methods by Sue Azam-Ali Practical Action Publishing, 2003
Useful organisations and contacts
Food and Agriculture Organization of the United Nations, Rome, Italy Viale delle Terme di Caracalla 00153 Rome, Italy Tel: +39-06-57051 Fax: +39-06-57053152 Email: FAO-HQ@fao.org Media Relations Tel: +39-06-57053625 Fax: +39-06-57053699
This document was produced by Barrie Axtell (2003) and updated by Tony Swetman (2008) for Practical Action. Practical Action The Schumacher Centre Bourton-on-Dunsmore Rugby, Warwickshire, CV23 9QZ United Kingdom Tel: +44 (0)1926 634400 Fax: +44 (0)1926 634401 E-mail: inforserv@practicalaction.org.uk Website: http://practicalaction.org/practicalanswers/
Practical Action is a development charity with a difference. We know the simplest ideas can have the most profound, life-changing effect on poor people across the world. For over 40 years, we have been working closely with some of the world’s poorest people - using simple technology to fight poverty and transform their lives for the better. We currently work in 15 countries in Africa, South Asia and Latin America.
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