実験食品化学ジャーナル

In recent years, technological revolution, nutritional awareness, and continuous demand for new generation have necessitated the search for new techniques of food processing in industries. Pulsed electric field is one of the emerging techniques to preserve the foods, especially the liquid ones such as milk, yoghurt, juices, soups, rice pudding, and liquid eggs, but not suitable for solid foods. It has the potential to produce the foods with excellent sensory and nutritional quality besides extends shelf life and ensures safety. Pulsed electric field uses short electric pulses to preserve the foods. This technology is best suited to pasteurize heat sensitive foods. It is hoped that India has great opportunity to develop this novel technology for the food processing. Emphasis is given to undertake comprehensive studies on the efficacy of pulsed electric field on various bacteria and fungi, which are associated with spoilage of foods.

Salt intake is an important concern for health reasons and saltiness is affected not only by content of food, but also by the texture. Surimi-based products, such as kamaboko, are elastic gels with approximately 2% NaCl; despite recent concerns among Japanese consumers regarding high-salt foods, little is known about the relationship between saltiness and texture in these products. This study was aimed to clarify the relationship between saltiness and texture using heat-induced surimi gels as a model of surimi-based product. Various types of heat-induced gels with different physical properties were prepared from surimi and washed surimi by two-step heating with different setting (preheating) times at 30°C. Washed surimi was prepared to remove the additives, because the additives were thought to affect the taste of surimi gel. The physical properties of heat-induced gels were characterized by puncture breaking strength and expressible water. The perceived saltiness of the heat-induced surimi gels was evaluated with fixed number of chewing. Next, to improve the demerit of this method, the perceived saltiness of the washed surimi gels was evaluated by free chewing conditions. The perceived saltiness after fixed number of chewing and the maximum saltiness intensity during free chewing was evaluated using sensory tests by comparisons with salt solutions of known concentrations. The physical properties of heat-induced gels differed considerably depending on the salt content and heating conditions. A longer setting time was associated with a higher breaking force and lower expressible water, regardless of salt content. On the other hand, perceived saltiness depended on the NaCl concentration, but not greatly influenced by the physical properties of the gels prepared from both surimi and washed surimi. The perceived saltiness of all gels tested was less than 1/3 of solution with the same NaCl concentration. The maximum saltiness intensity did not correlate with breaking force, breaking strain and expressible water of heat-induced gels. From these results, it was suggested that the difference in physical properties derived by setting did not affect the relative saltiness intensity of gels to NaCl solution during consumption of surimi gels.

The strength of taste is thought to be affected not only by content of food, but also by the texture. The previous study on the relationship between the saltiness and texture of heat-induced surimi gels prepared with different setting conditions revealed that the difference of physical properties did not affect the perceived saltiness of surimi gels, notwithstanding the breaking strength was very different according to the setting time. This result was seemed to contradict to the findings obtained with other food material so far. Therefore, this study was aimed to clarify the relationship between the intensity of saltiness and texture of heat-induced surimi-based products focusing on the fragmentation of the gel. To prepare various types of surimi gels having different physical properties from the same material, surimi gels were prepared by 2-steps heating with different level of pre-heating at 60ºC (modori). The physical properties of surimi gels were evaluated by puncture test, two-bite texture profile analysis and measurement of expressible water. The particle size of surimi gels after chewing in mouth by every panelist was also evaluated. The physical properties of heat-induced surimi gels became softer and more fragile according to the preheating time at 60ºC. Maximum saltiness intensity in the gel was evaluated comparing with different reference solutions. The result of the sensory evaluation suggested that the difference in physical properties derived by heat induced degradation during pre-heating at 60ºC affected the perceived saltiness during consumption of surimi gels, and that the fragmentation of the gel will strongly correlate to the perceived saltiness of surimi gels.