Proteolytic activities and profiles as useful traits to select barley cultivars for beer production.

Barley malting depends on hydrolytic enzymes that degrade storage macromolecules. Identifying barley cultivars with proteolytic activity that guarantees appropriate foaming, flavor, and aroma in the beer is of great importance. In this work, the proteolytic activity and profiles of brewing malt from Mexican barley cultivars were analyzed. Data showed that Cys- (at 50°C) and Ser-proteases (at 70°C) are the major contributors to proteolytic activity during mashing. Essential amino acids, necessary for fermentation and production of good flavor and aroma in beer, were detected at the end of mashing. According to our results, Mexican cultivar HV2005-19 exhibits similar proteolytic activities as those from cultivar Metcalfe, which is one of the most utilized for the brewing industry. Moreover, we propose Cys- and Ser-proteases as biochemical markers during mashing at 50 and 70°C, respectively, to select barley cultivars for beer production. PRACTICAL APPLICATIONS: Proteolytic activity, which depends on activation and de novo synthesis of proteases in the aleurone layer of barley seeds, is crucial in beer production. Identifying new barley varieties that have optimal proteolytic activities is of great interest for genetic improvement programs. In this study, we propose the variety HV2005-19 as a genotype with Cys- and Ser-proteases activity similar to that from Metcalfe, which is a top variety in the brewing industry.

Maíz nixtamalizado suplementado con un concentrado de proteínas de sardina para mejorar el valor biológico de las tortillas.

INTRODUCCIÓN: La mayor parte de la población rural en México adquiere casi la mitad de su energía de la tortilla de maíz y sus fuentes de proteína son principalmente de origen vegetal. OBJETIVO: Obtener un concentrado de proteína de sardina para adicionar harina de maíz e identificar la concentración que proporcione la mejor calidad biológica de las tortillas sin modificar sus características físicas y sensoriales. MÉTODO: Obtención de un concentrado de proteína de sardina y elaboración de tortillas con harina de maíz suplementada con diferentes concentraciones de proteína. Las características físicas y sensoriales de las tortillas fueron evaluadas por panelistas no entrenados. La calidad biológica de las tortillas se analizó en un modelo murino (crecimiento y la relación de eficiencia de proteína, PER). Para el análisis se utilizó estadística paramétrica. RESULTADOS: Se obtuvo un concentrado de proteína con 70.48 g/100 g. La suavidad, inflado, doblado y calidad de las tortillas preparadas con las mezclas con 0.63-3.75 % de proteínas de sardina fueron comparables con los de las tortillas elaboradas con harina no adicionada. El crecimiento de las ratas alimentadas con tortillas adicionadas fue mayor que el de las alimentadas con harina no adicionada; la diferencia fue significativa a partir de la concentración de 3.75 % (p < 0.05). El PER de las tortillas con 3.75 % de proteínas de sardina fue de 2.41, comparable al de la proteína de referencia (caseína). CONCLUSIÓN: La harina de maíz adicionada con proteínas de sardina en una proporción de 96.25:3.75 % mejora el valor biológico de las tortillas sin alterar sus características físicas y sensoriales. INTRODUCTION: Most part of the rural population in Mexico obtains almost half its energy from corn tortilla, and its sources of protein are mainly of vegetal origin. OBJECTIVE: To obtain a concentrate of sardine protein (SP) to supplement corn flour, and to identify which concentration provides corn tortillas with a better biological value, without modifying its physical and sensorial characteristics. METHOD: Obtainment of the SP concentrate, preparation of tortillas with corn flour and different SP concentrations, assessment of tortillas physical and sensorial characteristics by untrained panelists, assessment of biological quality in a murine model (growth and protein efficiency ratio [PER]). Parametric statistics was used. RESULTS: A protein concentrate of 70.48 g/100 g was obtained. Smoothness, blistering, foldability and quality of the tortillas prepared with mixtures containing 0.63-3.75% of SP were comparable to those of tortillas prepared with non-supplemented flour. The growth of rats fed supplemented tortillas was superior; the difference was significant with ≥ 3.75% concentrations (p < 0.05). The PER of tortillas with 3.75% of SP was 2.41, which was comparable to that of the reference protein (casein). CONCLUSION: SP-supplemented corn flour at a 96.25:3.75% ratio improves the biological value of tortillas without modifying their physical and sensorial characteristics.