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How should tasting tests be organised?

How should tasting tests be organised?


There is no substitute for tasting tests in assessing overall biscuit quality. After all, that is how the consumer will judge the product. Unfortunately, reliable tastings require a considerable amount of planning and administration.


There are two types of tasting test. There is the type which aims to detect differences between samples (biscuits or ingredients) that are supposedly similar and another type is used to record preferences and or individuals opinions about aspects of the product.


A common form of the difference test is the Triangular Test. This involves presenting three samples, two of one product and one of the other. The tasters are asked, "Can you detect a difference?", "Which two are alike?" and "Can you describe the difference?" Clearly the reason for the difference will only be valuable from those that correctly selected the odd sample. Often the two types of product being tested have some visual difference in addition to the eating quality difference. When this is the case it is necessary to conduct the tastings either under blindfold or with illumination that obscures the visual differences.


Some tasters may correctly guess the odd sample, it is therefore necessary to analyse the results statistically. Roessler* gives details and showed, for example, that if there were 10 tasters, difference would be proved at the highly significant and very highly significant levels (P=0.01 and P=.001) if 8 and 9 of the tasters were correct. With 20 tasters the numbers would be 13 and 14 respectively. It is the triangular type of tasting test that Quality Control will use mostly in monitoring product quality.


In the early stages of product development, it is people's opinion that is required from tasting tests. A great deal of literature has been published about scaling and ranking methods in these types of tasting tests. The size of the literature reflects the difficulties presented.


For preference tasting it is not so important to have trained tasters. Some people are more perceptive tasters than others, but with the principle of business involvement in mind, it is wise to seek interest and co-operation from ALL levels and types of staff in the company on matters involving the quality of its products.


*Roessler, E.B., Warren, J. and Guymon, J.F., (1948), Significance in Triangular Taste tests. Food Res 13, 503-505

Customer complaints

Customer complaints are an early warning that all may not be well in the QC system. Many companies have a free phone number printed on the package to encourage customers to let them know of problems and concerns.

Customer complaints will normally be addressed to the Sales and Marketing Department but Quality Control should take a significant position with respect to these and in particular about foreign matter in biscuits.

Customer complaints are mostly about stale biscuits but the most serious complaints are about foreign matter inclusions. Here prompt, responsible action is imperative. If a consumer is sufficiently concerned to notify a complaint he or she will become aggressive if not assured that the matter is being treated properly. The aggression may take the form of recourse to the authorities or a court of law which could involve the manufacturer in considerable expense and bad publicity. Not all customer complaints are justified and there are rogues whose main aims are free supplies. However, with good record keeping and keen observation of technical matters it is often possible to spot the hoax complainers. No complaint should be treated lightly as it may be an indication of an extensive or serious problem.

Quality control checks for packaging materials

Biscuits are very susceptible to the pick up of strong odours and even small traces can spoil their flavour.

Subtle problems may arise from solvents used in inks to print the wrappers so it is as well to discuss these problems with the converters of wrapping materials to ensure that adequate removal of odours takes place before the printed matter is reeled up or wrapped for delivery.

Cardboard may give a musty flavour note if in contact with biscuits within a moistureproof barrier. Always use good quality cardboard manufactured from new fibres (not recycled paper) and check carefully for odours that may be transferred to the products. It is permissible to use cardboard made from recycled paper for outer boxes which do not come into contact with the biscuits. It should be remembered also that recycled paper cardboard may present a hygiene hazard if placed in contact with food.

Moistureproofness is measured by the rate that moisture vapour passes across the film barrier when it separates an atmosphere of given humidity from one of zero humidity at a given temperature.

There are two standard test conditions known as (a) temperate (relative humidity of 75% at 25°C) and (b) tropical (relative humidity of 90% at 38°C).

Specifications for films should give the water vapour permeability (wvp) or water vapour transmission rate (wvtr) as g/m2/24 hours at one of the two standards given above. The important point to remember is that the performance may be affected if the film is creased or printed and the specification relates to flat basic film. In terms of the overall pack the performance is also usually affected by the quality of the seals.

Gas permeability properties (for example for oxygen) are specified in cm3/m2/24 hours/atm at 23±1°C. Although the gas permeability may not be well related to the wvp and also varies considerably for different gases, it is not normally felt necessary to check this property of films for biscuit wrapping.

The films must have good heat sealing properties because the seals compliment the basic film properties in the performance of the pack.

Storage of packaging materials

Cellulose films require protection from ambient moisture. If they absorb moisture (at the cut edges) they will expand and curl, making them difficult to run on the wrapping machine. Reels of cellulose film should therefore be stored in sealed polythene bags. Rather less care is needed for storing plastics films. Cardboard, however, whether as cartons or cases, needs very careful storage. The main problem is moisture pick up. If the paper should become damp it loses its strength and may become loosened from the adhesives inherent in the case design. It is not normally possible to wrap stocks of cases for protection, so they should be stored off the floor (on pallets), flat, to prevent distortions and in a well ventilated area, with low relatively humidity. To ensure low humidities in damp climates it may be necessary to install space heaters or dehumidifying machinery. Recent developments in the latter have made them very effective and economical.

Particular care should be used in storing small cartons which are to be run on automatic cartoning machines. Dampness will render the card weak and this will bend and interfere with the erection functions within the machine.

Quality control checks for finished product inspection

It has to be admitted that it is not possible to completely define and test for all the characters that make up a biscuit product. It is therefore necessary that QC staff are sensitive to variations that do or might occur in the processing which may affect the product quality and to make checks as appropriate. It is this understanding that will decide the frequency of sampling and checking. Under a good quality and process control culture QC staff will be informed promptly by production if there are difficulties which may affect the product quality. Through co-operation the correct actions will be agreed.

A view must be taken on how finished products should be adequately monitored bearing in mind that all the control systems in the factory should be aimed at preventing variation and contamination. As a result of spot checks the extent of some problems can be estimated with a view to tightening up controls earlier in the process. These may include checks on:

  • pack weights and examination of process control pack weight records
  • pack appearance, correctness of coding/overprinting
  • storage tests to check pack performance and product shelf life
  • recording the incidences of broken biscuits within packs.
  • organoleptic checks (tasting tests) on biscuit texture and flavour
  • metal detection facilities, review of "finds" from the automatic machines
  • warehouse conditions e.g. stacking and rotation of stocks
  • procedures for loading of trucks and damage during distribution.
  • storage conditions and stock rotation at depots.

Instruments may be installed to monitor pack weights and the records from these will be of great value. The instruments, usually known as check weighers, need to be calibrated and checked for correct performance at regular intervals. It must be decided who is responsible for this and a facility provided to confirm that checks have been made.

Metal detecting instruments also must be checked for correct performance regularly.

It is becoming more common for biscuits to be sold with precise claims of nutritional value. Where this is the case Quality Control must take adequate samples and make assays by approved methods to substantiate claims on the labels.

Reviews of results from these QC checks of packed production over a number of days or weeks may reveal shortcomings of packaging materials or various machines. It is the duty of the QC Manager to spot these points and to communicate with process control, engineering, product development, etc. staff to see if actions by production personnel could give improvements or whether a development project should be instigated.

Discovery of substandard packed stock requires urgent and logical management procedures. What is done depends on the nature of the problem and the attitude of the Sales Director. Just occasionally it may be necessary to recall stock that has left the factory and even got as far as the retailing shops. It is very important that thought is given to what to do in these circumstances before an incidence occurs. The press media have an unfortunate skill in humiliating management that is unprepared in incidents that cause public concern, even though they may be very rare.

Other materials

The use of old dough and recycled biscuits is a particular problem for quality control. Following all the care and attention invested in selecting and contracting to buy ingredients to tight specifications the indiscriminate use of old dough and rejected biscuits as ingredients tends to defy logic! The matter is considered more fully in the section on Management of waste.