A versatile instrument for measuring the texture of foods is described. It is based on a simple screw-operated press which accommodates a range of different test cells, including a new type recently developed. Force, deformation and time during the test are recorded with electronic apparatus. The system is designed so that it can be used for both research and production quality control applications efficiently and economically.
The evolution of the volatile substances during the fermentation of apple juices from four varieties was studied by gas chromatography. Fermentations with a single strain of yeast were followed for 90 days and samples from head space were taken regularly.
Differences between the juices are qualitatively very small. Generally there is an increase in the volatiles during the fermentation even if some exceptions exist.
Quantitatively characteristic differences are met in every variety and those differences are such that, by chromatographv, good indications may be obtained on the variety used in the preparation of the juice.
Gas liquid chromatography of volatile substances was done on four varieties of aple, being Fameuse, Russett, Mcintosh and Cotîand. Apples used were stored in a controlled atmosphere. The juice was prepared by washing, crushing, pressing, pasteurization and was stored at —40°C.
The juice sample was agitated for thirty minutes in the presence of 4 M sodium chloride solution, just before sampling the headspace gas by the Weurman technique for chromatography.
Each variety has its own characteristic volatile substances, from both qualitative and quantitative aspects. Butanol seems to be a marker substance for the Fameuse variety which contained approximately 100 times more of it than the Cortland variety. Iso-pentanol is characteristic of the latter variety in which the content was approximately 75 times higher than in the other varieties. The Russett variety was characterized by its high content of an unidentified substance and low concentration of butanol.
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