Food chemistry studies on enzymatic browning and the Maillard reaction were reviewed. Enzymatic browning can broadly be categorized into immediate and delayed types. We investigated the mechanisms and regulation of enzymatic browning of apple as an example of the immediate type, and browning of lettuce and mung bean sprout as the delayed type. The Maillard reaction is the major cause of non-enzymatic browning. However, melanoidins, which are the major brown pigments formed by the reaction, are large, heterogenous, high-molecular-weight compounds with chemical structures that are difficult to elucidate. We therefore focused on the low-molecular-weight pigments formed by the Maillard reaction. We identified various novel pigments in model systems and foods based on instrumental analyses.
Natural cheeses differ depending on the kind of milk and microorganisms used, as well as the conditions under which the cheese is matured. This study attempted to clarify the flavor components of bread containing Parmigiano-Reggiano cheese. We studied 32 components of model cheeses, including amino acids, fatty acids and organic acids. In order to identify the flavor-active components of the cheese bread, we performed omission and addition tests. The flavor of the cheese bread was affected by sodium glutamate, valine, methionine, isoleucine, leucine, phenylalanine, proline, and butyric acid. A principal component analysis identified the first principal component to be “rich flavor of cheese”, the second to be “baked flavor of bread”, the third to be “fermented flavor”; the overall flavor of the cheese bread comprised a balance of these flavor properties. Aldehydes and alcohols were increased by adding valine, methionine, isoleucine, leucine and phenylalanine. We considered that these compounds were formed due to yeast fermentation and the Maillard reaction. Bread to which these eight components were added had a bigger specific volume and softer crumbs than bread to which Parmigiano-Reggiano was added. The components that contributed most to the flavor of the cheese bread were clarified, and we were able to make good quality cheese bread without using real cheese.
In this study, mainly capillary electrophoresis-mass spectrometry based non-targeted metabolome analysis was conducted. Metabolomic profiles were determined for the peel, flesh, and core of the main melon fruit cultivars (cv Andes, cv Grace, and cv Quincy) grown in greenhouses and open fields in the Shonai area of Yamagata Prefecture. As a result, many metabolite concentrations showed high values in the fruit cores. Several amino acids such as GABA and alanine had especially high values, and physiologically active ingredients such as choline, trigonelline, and pyroglutamic acid were also significantly high. In addition, when metabolomic profiles of melon fruits grown in open fields and in greenhouses were compared, those amino acid concentrations tended to be higher in the flesh and cores in the open field cultivation. On the other hand, the core extracts of melon fruits were developed by effectively utilizing fruit processing residues that were discarded in abundance. They showed conspicuously higher concentrations of all amino acids and physiologically active ingredients such as GABA. This approach could be used to design new fruit products through objective evaluation of metabolomics.
Detailed optimization of the preparation conditions for Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf ) bran pickling beds was performed to develop the corresponding aged bran beds successfully with sufficient acidity based on excellent fermentability for daily use. The beds showed higher acidity than rice bran beds, and also showed effective performance as a starter. These results were achieved by finding the optimum moisture (water content), 52.5%, to prevent the formation of the characteristic stickiness typical of Adlay bran beds. The beds did not produce any propionic acid odor typical of rice bran beds. Instead, formation of branched alcohols and acids with chain lengths of C4 and C5 was detected by gas chromatography-mass spectrometry analyses. These compounds formed by the amino acid metabolism of yeast might produce the characteristic odor of the fermented Adlay bran beds.