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Decarboxylation of hydroxycinnamic acids by lactic acid bacteria strains isolated from dairy products.

G. Miyagusuku-Cruzado

Abstract:

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Decarboxylation of hydroxycinnamic acids by lactic acid bacteria strains isolated from dairy products.
G. Miyagusuku-Cruzado*, I. Garcia-Cano, D. Rocha-Mendoza, R. Jimenez-Flores, M. M. Giusti. The Ohio State University Columbus, OH.

Food flavor and aroma are significantly impacted by the presence of 4-vinylphenols (4VPs), volatile compounds with very low-perception thresholds produced by decarboxylation of hydroxycinnamic acids (HCAs) ubiquitous in nature. 4VPs can be found in dairy products such as cheese and yogurt, and when in low concentrations, they contribute positively to the flavor by adding complexity and uniqueness. In HCA-rich foods subjected to bacterial fermentation, it is key to select strains that will produce the desired sensory properties, highlighting the need for screening lactic acid bacteria (LAB) for decarboxylating ability. The decarboxylating activity of LAB strains from the Ohio State University—Parker Endowed Chair collection (137 strains) with potential to produce phenolic acid decarboxylase (22 strains) was evaluated after incubation with HCAs for 36 h at 32�C. Decarboxylation was monitored using a high-throughput spectrophotometric method based on hypsochromic shifts when HCAs are transformed into 4VPs. Spectrophotometric results were confirmed by HPLC-DAD-MS analyses, looking for longer retention times and shorter λ230—500 max than their precursor HCA, and characteristic m/z. Enterococcus mundtii, Lactobacillus plantarum and Pediococcus pentosaceus were capable of decarboxylating p-coumaric, caffeic and ferulic acids producing their 4VP derivatives. Seven other strains were only capable of biotransforming p-coumaric and caffeic acid, 1 was able to decarboxylate only caffeic acid and 1 was able to decarboxylate only p-coumaric acid, while 10 strains were not able to biotransform any HCA. No strain in this study was capable of decarboxylating sinapic acid. p-Coumaric acid had the highest biotransformation efficiency, followed by caffeic acid and lastly ferulic acid. This is the first study showing decarboxylating activity by the E. mundtii strain. This work can help improve LAB strain selection for food applications, improving the sensorial characteristics of fermented dairy products such as cheese and yogurt, especially the ones formulated with HCA-rich fruit and vegetable extracts.

Keywords: microbial biotransformation, fermented food, flavor compound.

Biography: Gonzalo Miyagusuku-Cruzado is a PhD candidate at The Ohio State University, and a coordinator in the Food Science Undergraduate Research Experience program. Born in Peru, he got a bachelor's degree in science from the Universidad Nacional Agraria La Molina. He received a master's degree in Bioscience and Biotechnology from Kyushu University sponsored by the Ministry of Education of Japan. Currently he conducts research on the enhancement of color and stability of anthocyanins under the guidance of Dr. Monica Giusti. Gonzalo enjoys playing handball and participated in South American tournaments with the Peruvian national team.