Study of lactic acid bacteria proteolytic capacity in a fermenting cacahuazintle corn

Abstract

As in symbiotic dairy fermented food, some released peptides during proteolysis of zein exhibit biological activity. Since there are not studies of peptides produced during fermentation of traditional Mexican foods like pozol, our objective was to determine the proteolytic capacity of Lactobacillus rhamnosus GG and Streptococcus thermophilus during fermentation of cacahuazintle corn and during the refrigerated storage of the ferment. Non-milk and milk corn fermentation were studied. The amount of protein was the same in both systems (2.37%). The fermentations were carried out at 37 °C to a pH of 4.5, which was reached after 26 hours in both systems. The fermented corn was stored at 4°C for 6 weeks. Proteolysis was evaluated by the concentration of primary amines by the technique of TNBS. At the end of the fermentation, the concentration of free amino groups was 4.4 mg/mL when milk was absent and 9.57 mg/mL when there was milk in the medium. At the end of the refrigerated storage, the free amino groups concentration was 5.6 mg/mL in non-milk fermentation and 8.6 mg/mL in the second one. Finally it was found that L. rhamnossus GG is capable of hydrolyzing zein.