Dynamics of Aroma-Active Volatiles in Miso Prepared from Lizardfish Meat and Soy during Fermentation: A Comparative Analysis

Abstract

Abstract:The evolution of aroma-active compounds during the maturation of lizardfish meat and soybean miso was quantified and characterized using the purge-and-trap method for volatile isolation. The results revealed that miso prepared from lizardfish meat and soybeans is the result of alcoholic fermentation rather than acid fermentation. The miso prepared from soybeans matured earlier (60-90 days) than that prepared from lizardfish meat (135 days). The constancy in the volatile lipid-oxidation products, including certain aldehydes and ketones, indicated the oxidative stability of both miso products throughout the fermentation period. The present findings indicated several compounds responsible for miso aroma, including 2-methylpropanal, 3-methylbutanal, 3-methyl-1-butanol, ethyl isobutyrate, 2-methylethyl butanoate, 3-methylethyl butanoate, ethyl decanoate, 2,3-butanedione, dimethyl trisulfide, methional, and 2-methyl butanoic acid. The formation of aldehyde can be attributed to the decomposition of hydroperoxides and peroxyl radicals, which are supposed to be initial products of oxidized fat. The volatile ketones were most likely the products of lipid and/or amino acid degradation also could possibly be produced from secondary degradation reactions involving diverse substances from the lipid during fermentation and/or may be derived from the Maillard reaction. Formation of the major volatiles in miso products were suggested as a combined effect of fungal metabolism of amino acids, sugars, and lipids, as well as the Maillard reaction during the fermentation period. The major difference between miso prepared from lizardfish meat and that from soybeans was the relative abundance of those odor-active compounds that finally characterize the products. Substrate specificmetabolic capacity of A. oryzae and the Maillard reaction were presumed to determine the flavor profile of the end product of miso.

Derivation of Kokumi γ-Glutamyl Peptides and Volatile Aroma Compounds from Fermented Cereal Processing By-Products for Reducing Bitterness of Plant-Based Ingredients

“…Overall, we observe a strong negative correlation between volatile aroma compounds and γ-glutamyl peptides (Figure 4). This observation may be explained by the cabalism of amino acids; for instance, aldehydes and alcohols are the primary compounds produced through the Ehrlich pathway by various fungal enzymes during fermentation [21] and Strecker degradation [53]. Therefore, the synthesis of kokumi peptides may be hindered as a result of the degradation of amino acids.…”