ACTA ALIMENTARIA VOL. 4 (A QUARTERLY OF THE COMMITTEE ON FOOD SCIENCE OF THE HUNGARIAN ACADEMY OF SCIENCES, 1975)
1975 / 1. sz. - KOVÁCS, E.-VAS, K.-BENCZE-BŐCS, J.: Objective determination of the heat treatment requirement of cooked potatoes
Acta Alimentaria, Vol. 4. (1), pp. 1—21 (1975) OBJECTIVE DETERMINATION OF THE HEAT TREATMENT REQUIREMENT OF COOKED POTATOES E. KOVÁCS, К. VAS and J. BENCZE-BŐCS (Received March 16, 1973) Hardness of 5 potato varieties (Gülbaba, Bintje, Désirée, Maryke, Jaerla) was studied during cooking at various temperatures (75— 95 °C), as a function of cooking time (0 '20 min) and of time of previous cold storage (0 — 6 months at 5— 10 °C). Hardness was measured instrumentally (Texturometer) and evaluated sensorically. It was found that cooking times, necessary to achieve 50% reduction in hardness, were similar for all varieties. Cooking times, needed to decrease hardness to a definite absolute value (e.g., Texturometer values 45 or 30), however, varied slightly with the variety, the slowest-cooking varieties being Bintje and Désirée. Appreciable differences in instrumentally measured cooking velocity could be demonstrated between potatoes before and after 5 or 6 months of cold storage. The potato lots stored for longer periods showed quicker softening under the same cooking conditions. Cooking velocity showed linear increase with increase in temperature. No varietal effect could be observed. Qln values ranged between 1.8 and 2.9, averaging around 2.0, and exhibited no dependence on variety or storage lime. Sensory and instrumental methods for determining hardness in potatoes showed some correlation. The instrumental measurement proved to be more sensitive and applicable to a wider range of hardness values than did sensory evaluation. In the knowledge (a) of the temperature history of the heat-treated tubers, (b) of the temperature dependence of cooking velocity and (c) of the objective (mechanical) standard of the hardness characteristics of the cooked state, the "cooking requirement" can be calculated. In this way the exact requirements of heat treatment can be determined and degradation of texture and wastage of heating energy, both being consequences of overcooking, can be avoided. An ever-growing portion of the potato crop is being processed by the food industry (HAMPSON, 1969; PAULUS, 1971; UHLMAHN, 1972). One of the processing methods is heat treatment. Of the various forms of heat treatment, cooking is an important operation not only from the point of view of culinary technology, but also from that of the production of canned (sterilized) potatoes whicli appear to be in great demand with the consumers in many countries. Apart from microbiological considerations, knowledge of the heat treatment required to bring about the "cooked" state of the potato, so as to avoid unnecessary overcooking (i.e., undesirable texture, energy wastage, etc.), is of technological and economic importance. Exact determination of the cooking requirement is fairly difficult at present. However, it was thought possible to solve this problem (a) by finding an objective standard for the cookcd state, (b) by determining the rate Acta Alimentaria 4,1975