know in detail about food analysis procedures and their techniques
Food Analysis
Food analysis is concerned with the development of criteria of quality and identity, with techniques suitable for use in the laboratory.
In earlier times, the food analyst was mainly concerned with gross adulteration. Nowadays, since there is an increasing tendency to manufacture foods about market requirements, processed foods, and fast foods are fast developing.
The food analysis is done with one or more of the three different objectives.
- Developing safe foodstuffs with consumer acceptance.
- The legal point of view for the sake of prosecution
- From the research point of view in educational institutions and research organisations
Processed foods are produced within the units of prescribed manufacturing standards, also set to comply with legal or other recognised requirements.
This is attained by standardising as far as possible, the process at each stage, from the farm to the dining table. This has resulted in the development of analytical techniques which are suitable for rapid assessments and control.
Earlier methods are about subjective criteria like flavour, texture, colour, and other qualities were preferred. However, now methods that give quick, reproducible, accurate and objective procedures are replacing the subjective methods for the evaluation of food quality.
Many of the food analysis procedures have been empirically developed with special reference to the particular food product. Such methods are precise or reproducible. Most of these procedures also yield accurate results.
The procedure is given for the analysis of a particular compound need not be applicable for a similar compound. In many food laboratories, most of the routine work comprises methods of proximate analysis and the study of colour additives and contaminants.
The main compositional components of interest are moisture, fat, protein, ash available and unavailable carbohydrates. The moisture value obtained by drying methods may include other volatile matter such as essential oils, traces of volatile acids and amines.
The preparation of the samples plays a vital role in food analysis. Sugars from natural sources such as fruits are conveniently expressed as total soluble solids as measured by refractometric determination.
Protein can be calculated from the total nitrogen as determined by Kjeldahl’s method. In many estimations, allowance has to be made for interference arising from the food itself or contamination of the reagents, and blank determination must be performed. Allowance may sometimes have been made for changes that occur during storage.
Internationally recognised reference procedures have been published by bodies such as ISO, IUPAC, Codex Alimentarius and the AOZC in the UK, the British standards institution and the analytical division of the chemical society.
As in other fields of analysis, the availability of suitable methods is essential if accurate results are to be obtained. Good results depend on the choice of the experiment, the analytical procedures used and the accurate determination and interpretation of the results.
The food analyst should be acquainted with the theory of each estimation and should strive for accuracy. With the available equipment, the food analyst decides on the feasible methods to be used in the laboratory.
Sampling – Food Analysis
The perfect sample is 100% of the food material being analysed. This is possible only when the quantity of the food to be analysed is small enough.
For a high quantity of food, a representative sample is usually obtained. When the food particle is homogeneous, a sample can be taken.
However, when the food is heterogeneous, the problem of getting a sample is difficult. Hence the food analyst should be familiar with the sampling procedures.
The value of the result of chemical analysis on a well-prepared laboratory sample depends on how representative of the sample is of the lot, batch, package, or consignment of the particular food from which it was taken and on the kind of chemical information that is required.
Foodstuffs and food ingredients are relatively heterogeneous materials, so it is difficult to obtain a single representative sample for sample analysis.
The problem may be minimised by selecting, either randomly or according to a plan several samples from the lot. These samples may be analysed separately to yield results from which the average composition of the lot may be computed.
In some instances, the samples may be thoroughly mixed to give a single large representative bulk sample from which a sample may be taken for laboratory analysis.
The process of sampling is one facet of statistics, and most books on statistics include chapters describing the elementary mathematical principles involved.
There are ISO standards for the sampling of various foodstuffs. Because of the practical difficulties and economic aspects of full statistical sampling, and the natural variation in the composition of foodstuffs, food analysis is often out randomly chosen single samples.
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