Abstract This study deals with the ability of probiotic bacteria to ferment prebiotics in vitro to estimate the prebiotic activity score and prebiotic index based on specific substrates and strains. Five probiotic bacteria were isolated from commercial products and their fermentation capability of three commercial prebiotics was assessed. Growth kinetics of probiotics showed that all of them were able to use the prebiotics as carbon sources. Mostly bacteria grew faster on Frutafit and Oligomate 55 than on lactulose. The prebiotic activity score and prebiotic index concepts were introduced to evaluate the performance of every probiotic with each prebiotic; accordingly, the highest values were for L. rhamnosus on Oligomate 55, while the worst according to these parameters was L. casei Shirota on Frutafit. Prebiotic index and prebiotic activity score describe well the selective growth of probiotics supported by prebiotics; therefore, they could be useful tools to define adequate combinations in colonic foods development.

Abstract In this study, the survival and proteolysis of lactic acid bacteria Lactobacillus casei Shirota and Lactobacillus rhamnosus GG were measured in fermented milks enriched with agave juice and inulin. Fermentations were terminated at pH 4.5 and stored for 21 days at 4 °C. Survival was determined by viable count in MRS-agar. The production of free amino groups was performed by the TNBS method and peptide separation was performed by SDS-PAGE. During fermentation, pH decreased faster in milk with agave juice than with inulin. There was no significant difference in the concentration of free amino groups (0.632 ± 0.007 and 0.627 ± 0.007 mg/L) between the two fermentation systems for any microorganism. The concentration of lactic acid bacteria in the presence of agave juice was higher than the recommended concentration for probiotic foods (7.59 log CFU/mL for L. rhamnosus GG and 8.26 log CFU/mL for L. casei Shirota). The production of free amino groups and peptides of low molecular weight continued in refrigeration and was higher in systems with agave juice. This could represent a proteolytic activation in the presence of this carbon source. The results showed that agave juice might be a functional ingredient with prebiotic character in symbiotic systems.

There is a great variety of fermented milks containing lactic acid bacteria that present health-promoting properties. Milk proteins are hydrolyzed by the proteolytic system of these microorganisms producing peptides which may also perform other functions in vivo. These peptides are encrypted within the primary structure of proteins and can be released through food processing, either by milk fermentation or enzymatic hydrolysis during gastrointestinal transit. They perform different activities, since they act in the cardiovascular, digestive, endocrine, immune and nervous systems. Bioactive peptides that have an antihypertensive, antithrombotic, antioxidant and hypocholesterolemic effect on the cardiovascular system can reduce the risk factors for chronic disease manifestation and help improve human health. Most studied bioactive peptides are those which exert an antihypertensive effect by inhibiting the angiotensin-converting enzyme (ACE). Recently, the study of these peptides has focused on the implementation of tests to prove that they have an effect on health. This paper focuses on the production of ACEinhibitory antihypertensive peptides from fermented milks, its history, production and in vivo tests on rats and humans, on which its hypotensive effect has been shown.

Existe una gran variedad de leches fermentadas con bacterias lácticas, con propiedades que promueven la salud. Recientemente se ha comunicado que las proteínas de los alimentos pueden, además, ejercer otras funciones in vivo, por medio de sus péptidos con actividad biológica. Estos péptidos se encuentran encriptados dentro de la estructura primaria de las proteínas y pueden ser liberados por fermentación de la leche, hidrólisis enzimática, o bien durante el tránsito gastrointestinal. Las funciones que presentan son diversas, ya que pueden actuar en diferentes sistemas del cuerpo humano: el cardiovascular, el digestivo, el endocrino, el inmune y el nervioso. Los péptidos bioactivos que presentan un efecto en el sistema cardiovascular (antihipertensivo, antitrombótico, antioxidante o hipocolesterolémico) pueden reducir los factores de riesgo para la manifestación de enfermedades crónicas y ayudar a mejorar la salud humana. Los péptidos bioactivos más estudiados son aquellos que ejercen un efecto antihipertensivo a través de la inhibición de la enzima convertidora de angiotensina (ACE). Este documento se enfoca en la producción de péptidos antihipertensivos inhibidores de la ACE en leches fermentadas, en su historia, y en las pruebas in vivo realizadas en ratas y en humanos, donde se ha demostrado su efecto hipotensor.