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  • Author or Editor: Gy. Pátkai x
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Five different Jerusalem artichoke cultivars were investigated to compare their nutritional value. Investigations were carried out on samples harvested in December 2004 and stored until the end of March 2005 under natural climate in prism, in cold store and also after over-wintering in the soil. Investigations were repeated in 2005 and 2006. According to the results of storage outdoors in prism and in cold store, the total-and soluble solid content, the total carbohydrate and inulin content (w/w) did not change significantly as a function of storage time. Changes in sucrose-and reducing sugar content and that of glucose/fructose ratio were also insignificant. There was no significant difference in the ratio of carbohydrates of the tubers stored under those two above-mentioned conditions, however, there was a significant difference in the carbohydrate composition of the tubers harvested in winter or in spring.Compared to the majority of vegetables, the main nutrient of Jerusalem artichoke tubers is inulin, instead of starch. Total carbohydrate content of the tubers is divided into 80–90% inulin, 7–14% sucrose and 3–6% reducing sugars, on average. Because of its high average yield and outstanding inulin content, this is a plant of great interest as raw material for inulin and fructose processing, as well.The cultivar “Ceglédi” is, first of all, suggested for industrial processing. The present research data verified its outstanding inulin content and a high fructose/glucose ratio, too.

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Fibre-rich fruit juices are playing an increasing role in healthy nutrition, and consumers are regarding them, especially citrus juices of 100% fruit content, as reliable sources of vitamin C. Nevertheless relatively few scientific data are available on vitamin C retention during the heat treatment of aseptically packed fruit juices made from fruit concentrates. Authors investigated this problem within the scope of OTKA T 014965 research project (Körmendy et al., 1998, 1999a, 1999b; Pátkai, 1998).

Instead of separate case studies on different types of fruit juices and technologies, authors analysed the vitamin C content of model solutions with similar composition to real citrus juices as a function of temperature and duration of heat treatment and that of initial oxygen and ascorbic acid concentration. Based on the measured data, they elaborated kinetic relations and determined the reaction rate constants of vitamin C decomposition under the experimental conditions. By means of the calculated kinetic relations and reaction rate constants one can estimate the losses of vitamin C in the case of known parameters of the heat treatment, packaging material, oxygen and vitamin C concentration within the investigated domain. Results may promote technology and product development in the field of citrus fruit juices.

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