Clara Fuciños

Effects of Feeding of Two Potentially Probiotic Preparations from Lactic Acid Bacteria on the Performance and Faecal Microflora of Broiler Chickens

The aim of this study was to evaluate the potential of two probiotic preparations, containing live lactic acid bacteria (Lactococcus lactis CECT 539 and Lactobacillus casei CECT 4043) and their products of fermentation (organic acids and bacteriocins), as a replacement for antibiotics in stimulating health and growth of broiler chickens. The effects of the supplementation of both preparations (with proven probiotic effect in weaned piglets) and an antibiotic (avilamycin) on body weight gain (BWG), feed intake (FI), feed consumption efficiency (FCE), relative intestinal weight, and intestinal microbiota counts were studied in 1-day posthatch chickens. The experiments were conducted with medium-growth Sasso X44 chickens housed in cages and with nutritional stressed Ross 308 broiler distributed in pens. Consumption of the different diets did not affect significantly the final coliform counts in Sasso X44 chickens. However, counts of lactic acid bacteria and mesophilic microorganisms were higher in the animals receiving the two probiotic preparations (P < 0.05). In the second experiment, although no differences in BWG were observed between treatments, Ross 308 broilers receiving the probiotic Lactobacillus preparation exhibited the lowest FCE values and were considered the most efficient at converting feed into live weight.

Design of whey protein nanostructures for incorporation and release of nutraceutical compounds in food

ABSTRACT Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relatively inexpensive, generally recognized as safe (GRAS) ingredient, and possess important biological, physical, and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils, or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage, and moderate electrical fields, high pressure, temperature, pH, and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils, and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants, and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices.

Modelling the Biphasic Growth and Product Formation by Enterococcus faecium CECT 410 in Realkalized Fed-Batch Fermentations in Whey

The influence of initial pH on growth and nutrient (total sugars, nitrogen, and phosphorous) consumption by Enterococcus faecium CECT 410 was studied during batch cultures in whey. With these data, two realkalized fed-batch fermentations were developed using different feeding substrates. The shift from homolactic to mixed acid fermentation, the biphasic kinetics observed for cell growth and nitrogen consumption and the increase in the concentrations of biomass and products (lactic acid, acetic acid, ethanol, and butane-2,3-diol) were the most noteworthy observations of these cultures. Modelling the fed-batch growth of Ent. faecium with the Logistic and bi-Logistic models was not satisfactory. However, biomass production was best mathematically described with the use of a double Monod model, which was expressed in terms of biomass, product accumulation, and nitrogen utilization. Product formation was successfully modelled with a modified form of the Luedeking and Piret model developed in this study.

Pediocin SA-1: A selective bacteriocin for controlling Listeria monocytogenes in maize silages

In this study, we assessed the potential as silage additive of a bacteriocin produced by Pediococcus acidilactici Northern Regional Research Laboratory (NRRL) B-5627 (pediocin SA-1). Maize was inoculated either with a bacterial starter alone (I) or in combination with the bacteriocin (IP), and untreated silage served as control. We monitored the products of fermentation (ethanol, and lactic and acetic acids), the microbial population, and the presence of the indicator strain Listeria monocytogenes Colección Española de Cultivos Tipo (CECT) 4032 (1×10(5) cfu/g) after 1, 2, 5, 8, 16, and 30d of ensiling. Our results indicated antilisterial activity of the bacteriocin, anticipating the disappearance of L. monocytogenes in IP compared with I and control silages. The PCR-denaturing gradient gel electrophoresis analysis revealed the addition of the bacteriocin did not affect the bacterial communities of the spontaneous fermentation, and the inoculant-containing bacteria (Lactobacillus plantarum, Lactobacillus buchneri, and Enterococcus faecium) were found in addition to the bacterial communities of untreated maize silages in I and IP silages. Both treatments increased the concentration of antimicrobial compounds (acetic acid, ethanol, and 1,2-propanodiol) and led to lower residual sugar contents compared with the control, which would provide enhanced aerobic stability. The fact that the identified species L. plantarum, L. buchneri, and E. faecium produce some of these inhibitory compounds, together with their persistence throughout the 30d of fermentation, suggest these bacteria could actively participate in the ensiling process. According to these results, pediocin SA-1 could be used as an additive to control the presence of L. monocytogenes in maize silages selectively, while improving their fermentative quality and eventually their aerobic stability.

Modelling the enzymatic activity of two lipases isoenzymes commonly used in the food industry Modelado de la actividad enzimática de dos isoenzimas lipasas comúnmente utilizadas en la industria alimentaria

An in-depth analysis of the kinetics of two lipases isoenzymes (Lip1 and Lip2) in triacetin hydrolysis in absence and in presence of hexane was carried out. The addition of hexane led to an increase in enzymatic activities of both enzymes for all triacetin concentrations, and the kinetic data described a hyperbola which was consistent with the classical Michaelis–Menten model. Without hexane, the time-course of the triacetin hydrolysis by Lip1 and Lip2 did not follow a Michaelian behaviour. In this case, a first phase of low enzymatic activity (at triacetin concentrations from 0 to 250 mM) was followed by a rapid increase in velocity at triacetin concentrations ≥250 mM. The Michaelis–Menten model was unable to describe the first phase due to the linear (nonhyperbolic) relationship between the velocity and the triacetin concentration, meanwhile the logistic model provided a satisfactory description of the experimental data corresponding to the second phase of activity. En este trabajo se llevó a cabo un profundo análisis de la cinética de dos isoenzimas lipasas (Lip1 y Lip2) en la hidrólisis de triacetina, en ausencia y en presencia de hexano. La adición de hexano a la mezcla de reacción incrementó las actividades enzimáticas de ambas enzimas para todas las concentraciones de triacetina, obteniéndose una relación hiperbólica compatible con el modelo clásico de Michaelis-Menten. En ausencia de hexano, la actividad de Lip1 y Lip2 no mostró un comportamiento Michaeliano, observándose una fase inicial de baja velocidad a concentraciones de triacetina entre 0–250 mM, seguida de un rápido incremento en la actividad enzimática ([triacetina] ≥ 250 mM). El modelo de Michaelis-Menten no pudo ser utilizado para describir la primera fase debido al incremento lineal (no hiperbólico) de la velocidad con la concentración de triacetina, mientras el modelo logístico describió adecuadamente la cinética de hidrólisis en la segunda fase.

Chapter 28 – Smart Nanohydrogels for Controlled Release of Food Preservatives

The food industry faces great challenges. Consumers, for example, prefer fresh or minimally processed food, while market globalization lengthens storage and distribution times. Fortunately, innovative packaging strategies are emerging to ensure food safety and to minimize losses caused by spoilage microorganisms. This chapter reviews the research on antimicrobial active and smart packaging: its basis, categories of packaging devices and antimicrobial compounds used, mode of incorporation, and commercial applications. The chapter also addresses the role of nanotechnology in food packaging, closely examining the use of smart environmentally sensitive nanohydrogels in overcoming the limitations of the classical active packaging systems. Specifically, poly (N-isopropylacrylamide) nanohydrogels are key for their physicochemical properties, releasing mechanisms, and antimicrobial effectiveness. The chapter provides examples of their role in controlling food spoilage fungi and discusses future prospects.