Reaktionskinetik der Bildung von Furfural in Abhängigkeit von Erhitzung, Konzentrierung und Lagerung in Orangensäften und ‐konzentraten

Abstract

According to studies on an orange concentrate diluted back with distilled water to the desired extract content, the formation of furfural follows the pattern of a consequent reaction. After the induction period, the reaction curve takes a linear course cooresponding to a reaction of a zero order. The temperature dependence of the resultant reaction constant k obeys the ARRHENIUS equation and yields the same energy of activation for all the extract contents under investigation. This is a case of specific acid catalysis, because the reaction velocity is directly proportional to the hydronium ion activity. On a semilogarithmic scale, the dependence of the k values of the extract contents of the concentrates and of the re-constituted juice can be presented for various temperatures in the form of parallels. According to the literature, the amount of the furfural produced correlates with the quality of the orange juices and concentrates. Consequently, this amount might be used as an indicator in evaluating quality deteriorations due to unsuitable manufacturing and storage on the one hand, and for the computation and optimization of the manufacturing processes and parameters on the other hand.

Aseptically packaged orange juice and concentrate: a review of the influence of processing and packaging conditions on quality

“…TEMPERATURE ABUSE Nagy and Randall (1973) reported furfural was not the component responsible for flavor changes in storage temperature abused orange juice; however, furfural levels have been reported to closely parallel the extent of flavor differences in orange juices (Nagy and Randall, 1973) and grapefruit juices (Nagy et al, 1972;Maraulja et al, 1973). Herrmann and Partassidou (1979) reported furfural formation in orange juices and concentrates at temperatures ranging from 36 to 100 °C followed the pattern of a sequential reaction. After an induction period, the reaction curve was found to be linear corresponding to a zero-order reaction.…”

Approaches to the citrus browning problem. A review

“…Since it was observed that ascorbic acid breakdown in orange juice results in furfural production and furfural buildup closely parallels quality loss in citrus products, furfural indexing has been proposed as a basis for quality control (Dinsmore and Nagy, 1972;Nagy et al, 1972;Nagy and Randall, 1973; Nagy and Dinsmore, 1974;Herrmann and Partassidou, 1979). It is not that furfural, per se, contributes appreciably to off-flavor; the levels present are below the taste detection threshold (Nagy and Dinsmore, 1974).…”