Enhancement of cheese flavors with microbial esterases

The characteristic flavor of hard Italian cheeses is associated with the presence of fatty acids, particularly butyric acid, liberated from milk fat during the ripening process. To ensure proper development and control of flavor, animal pregastric esterases or lipases are routinely added to the milk before coagulation of the curd. Such esterases are also used to generate flavor in enzyme modified cheese and other dairy products. Esterases from microbial sources have been investigated as agents to enhance flavor in cheese. We have found that an esterase from Mucor miehei exhibits the type of lipolytic activity needed for this application. Romano and fontina cheeses of excellent quality have been prepared by the use of this esterase. It has also been used successfully in the preparation of enzyme modified cheese, and, in turn, processed American cheese.     

COMPARISONS OF VOLATILE COMPOUNDS RELEASED DURING CONSUMPTION OF A COMPLEX FOOD BY DIFFERENT ASSESSORS WITH EXPRESSIONS OF PERCEIVED FLAVOR DETERMINED BY FREE CHOICE PROFILING

Comparisons of volatile compounds released during consumption by different assessors with individual differences in the assessors'chewing patterns, saliva production rates and ultimately their expressions of perceived flavor have received little research attention to date, although such comparisons are fundamental to the understanding of flavor. To address this, eight untrained assessors were chosen and each consumed six Cheddar cheeses during Buccal Headspace Analysis of the volatile compounds released, while in parallel measures of each assessor's mastication behavior using Electromyography, their stimulated saliva production during consumption and their sensory perceptions of the cheeses flavor during Free Choice Profiling were determined. Relationships between the volatile compounds released and the sensory and physiological measures were investigated using Principal Components Analysis, Generalised Procrustes Analysis and Partial Least Squares regression. It was found that although there were differences between assessors'mastication behavior and saliva production rates, the assessors'individual volatile profiles obtained by Buccal Headspace Analysis were similar for each cheese examined. Also, Partial Least Squares was successful in predicting the most important flavor differences between cheeses from the volatile compounds released during their consumption by different assessors.     

Flavor Characteristics of Glutathione in Raw and Cooked Foodstuffs

The flavor of glutathione (γ-l-glutamyl-l-cysteinylglycine, GSH) was examined by several sensory evaluations. The measurement of a point of subjective equality (PSE) showed that the peptide increases the flavor characteristics but did not affect the intensity of basic tastes, such as sweetness, saltiness, sourness, and umami. However, the threshold value of GSH decreased significantly in an umami solution containing 0.05% each of monosodium glutamate (MSG) and disodium inosinate (IMP). This suggests that GSH interacts with the umami substance and has a certain effect on the flavor.

GSH had a characteristic kokumi flavor, such as continuity, mouthfulness, and thickness in the umami solution as well as in a model beef extract constructed from analyzed components at a concentration of 0.02% w/v. Some foodstuffs, including meat, were found to contain GSH above its threshold value, which implicates the contribution of GSH to the flavor.

The thermal degradation study suggested that a part of GSH have changed into its disulfide, pyroglutamic acid (PCA), and cyclocysteinylglycine in cooked foodstuffs.