DEVELOPMENT OF A SAMPLING METHODOLOGY FOR THE PROPER EVALUATION OF THE QUALITY OF THE PROCESSING TOMATOES

In order to overcome the problem of expensive machinery for industrial sampling of the processing tomato we have tried to develop with low cost of investment, a sampler which could carry out a proper, reliable and representative sampling and to find the proper quality attributes which could be used to give reliable results.

The whole work included two stages;

A. In the first stage three methods of sampling were used. I. 25 small samples 2Kg each, II. 5–10 samples of about 13Kg. III. 5 samples created from seven sub-samples taken sequentially during the whole time of truck unloading.

The samples were taken from a small chanel fitted to the side of the truck. The product was unloaded through this channel by a stream of water. The third method of sampling was characterized by significantly lower variance of brix values and for this reason it is considered the most reliable. The variance of values in the rest of the quality characteristics was found to be very low fact which indicates that the product is highly uniford concerning these attributes.

B.In the second stage an automatic sampler was constructed based on the results of the first stage. This sampler was working on the principles of the third method of sampling. Actually the sampler is a modification of the small chanel fitted to the side of the truck. A small door fitted underneath or on the side of the chanel can be opened/closed pneumatically in time intervals controlled electronicaly. In each truck a sample was made up by the automatic sampler and at the same time 30–40 small samples of about 4kg were taken manually.

Eventhough a great dispersion of brix values was found between the small samples, the mean value of all these samples was found to be very close to the value of the sample obtained by the automatic sampler. This method of sampling could be automised to a high degree and could be used by the industry since it is simple, reliable and could be carried out with a very low cost of investment.