Optimized synthesis of citronellyl flavour esters using free and immobilized lipase from Rhizopus sp.

Microbial lipase produced by Rhizopus sp. was tested for the synthesis of citronellyl butyrate and citronellyl valerate. Lipase showed more ability to catalyze the synthesis of citronellyl butyrate. This process was optimized using response surface methodology (RSM) based on a five-level, two variable central composite rotatable design (CCRD). The optimum conditions were molar ratio of 2.41:1 (alcohol: acid) and lipase amount of 6.12% (w/w) and the yield achieved 100% (molar conversion) in 48 It. Lipase was also immobilized onto celite and its activity improved, leading to 100% molar conversion in 24 h. However, immobilized lipase did not exhibited operational stability after a few reaction cycles. (c) 2005 Elsevier Ltd. All rights reserved.40103181318

STORAGE TIME STUDY OF SUGAR-FREE AND REDUCED CALORIE MILK CHOCOLATES

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In order to study storage time, sensory properties and acceptability among consumers, regular, free-sugar (sucralose [Sucra] or stevioside [Ste]) and free-sugar/reduced calorie (Sucra or Ste], with whey protein concentrate as fat replacer) milk chocolates were evaluated over storage (0, 3, 6 and 9 months). Quantitative descriptive analysis showed that sensory properties do not change throughout the studied storage period. These results were confirmed by acceptability data. No significant changes (P >= 0.05) were observed on acceptability means for appearance, aroma, flavor, texture and overall liking. These results show that sugar-free and reduced calorie milk chocolates prepared with high-intensity sweeteners, Sucra and Ste, with partial fat replacement with whey protein concentrate had a similar storage time behavior as compared with regular chocolates. PRACTICAL APPLICATIONS This research aims to study sensory storage time of regular, sugar-free and sugar-free/reduced calorie milk chocolates. It can help food industries to understand storage time of these products as sensory properties for highly stable food products, such as chocolate, usually define shelf life.325577589Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Optimizing the synthesis of citronellyl valerate using lipase from Rhizopus sp

Citronellyl valerate was synthesized by a lipase from a Rhizopus sp strain isolated and the lipase produced, at UNICAMP, Brazil. Direct esterification was performed in a solvent-free medium to produce the flavor ester. Response surface methodology was used to optimize the process with respect to the substrate molar ratio and lipase concentration. The results show that the synthesis of citronellyl valerate can be carried out in a solvent-free medium, the maximum ester conversion rate achieved being 91.5% after 48 hours of reaction time.14336837

Time-intensity profile and internal preference mapping of strawberry jam

Time - intensity analysis was applied for sweet and sour tastes and strawberry flavor of six commercial brands of strawberry jam. For this test, 11 subjects, between 25 and 35 years old, were selected from an initial 12-member group. An affective test, with 117 consumers was also carried out and the results were analyzed by internal preference mapping. The least accepted samples were the ones with the lowest sweetness intensity, indicating that jam consumers prefer sweeter products. Also, one of them presented a higher sourness intensity, which may have had a negative influence on its acceptance. It is important to point out the fact that those least accepted samples were the low-calorie products. The internal preference mapping and cluster analysis showed two consumer clusters. The first one was a higher concentration of consumers toward traditional samples, and the second one showed a lower concentration of consumers in the direction of one of the low-calorie samples.23112513