A COMBINATION OF GLUTAMINASE AND pH CONTROL PREVENTS THE NONENZYMATIC CONVERSION OF l‐GLUTAMINE INTO l‐2‐PYRROLIDINE‐5‐CARBOXYLIC ACID IN FOOD PROCESSING

Abstract

A strategy using Alicyclobacillus F-62 glutaminase was established to minimize the nonenzymatic production acid was influenced by pH and temperature, and decreased over a pH range of 4-6 at 30C. Under optimum conditions (30C and pH 5.0), the L-glutamic and L-pyroglutamic acids obtained from 1 mM L-glutamine in the presence of glutaminase from Alicyclobacillus F-62 were 0.96 and 0.03 mM, respectively. This novel method is useful for the efficient production of L-glutamic acid during food-protein processing. 4 Corresponding

Metabolomic Insight into Soy Sauce through 1H NMR Spectroscopy

“…GABA is then transaminated to succinic semialdehyde by GABA transaminase, and finally succinic semialdehyde is oxidized to succinate by its dehydrogenase. During brine fermentation, the dehydrogenation of 2-oxoglutarate could contribute to high levels of glutamate, because glutaminases, which convert glutamine into glutamate, are produced by microorganisms and are inactivated at acidic pH and high salt . It is also well-known that fungi and LAB accumulate GABA via decarboxylation of glutamate , .…”

“…It is therefore likely that GABA and succinate levels, as well as glutamate levels, increase during the fermentation or aging of soy sauce. In general, pyroglutamate is known to be a derivative of glutamate or glutamine and is negatively associated with the flavor of soy sauce because it causes flavorless soy sauce , . Decreasing the conversion of glutamate or glutamine into pyroglutamate would therefore improve the quality of soy sauce.…”

Identification of a glutaminase-producing bacterial strain isolated from Thai fermented pork sausage and characterisation of glutaminase production

“…Glutaminases from A. oryzae and M. luteus K-3 have been demonstrated to play potentially significant roles in fermentation processes that require high-salt environment such as soy sauce fermentation (Nakadai and Nasuno, 1989;Moriguchi et al, 1994). A strategy using Alicyclobacillus F-62 glutaminase has been proposed to minimise the nonenzymatic production of L-pyroglutamic acid and maximise the enzymatic production of L-glutamic acid from L-glutamine in food-protein processing (Yoshimune et al, 2006). The glutaminase from K. gibsonii JRT-7 is expected to be applicable to food process such as Nham fermentation, where it potentially has an important role as a flavour enhancer through the catalysis of L-glutamine hydrolysis to L-glutamic acid, However, a better understanding of K. gibsonii JRT-7 glutaminase is necessary, and purification and characterisation is in progress.…”

“…Microbial glutaminases have been studied with the aim of adapting them to food processes; most studies to date have focused on their applications to Japanese soy sauce fermentation (Nandakumar et al, 2003). In addition to catalyzing the conversion of L-glutamine to L-glutamic acid, glutaminase also controls the non-enzymatic production of the tasteless amino acid, L-pyroglutamic acid from L-glutamine (Yoshimune et al, 2006). Bacterial γ-glutamyltranspeptidase and glutaminase -asparaginase efficiently increase L-glutamic acid content in Japanese soy sauce fermentation, producing a more flavourful product (Wakayama et al, 2005;Kijima and Suzuki, 2007).…”

Studies on Characteristic of Extracellular L–Glutaminase and Identification of L-Glutaminase Producing Bacterial Strain from Cattle Feeding Farm of Chhatrapati Sambhajinagar, Maharashtra State, India

“…Microbial glutaminases have been studied with the aim of adapting them to food processes; most studies to date have focused on their applications to soy sauce fermentation was proved (6). In addition to catalyzing to convert from L-glutamine to L-glutamic acid, glutaminase also controls the non-enzymatic production of the tasteless amino acid, L-pyroglutamic acid from L-glutamine (7). Bacterial γ-glutamyl trans peptidase and glutaminase -asparaginase efficiently increase L-glutamic acid content in soy sauce fermentation, producing a more flavorful product (8,9).…”