M. Miguez

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.

APTITUD DE VARIEDADES DE PATATA PARA SU TRANSFORMACIÓN EN BARRITAS PREFRITAS APTITUDE OF VARIETIES OF POTATO FOR ITS INDUSTRIAL TRANSFORMATION IN FRIED POTATOES SLICES

Abstract Six varieties of potatoes (Agria, Désirée, Europe, Hérmes, Kennnebec and Stemster) grew in Xinzo de Limia (Ourense) were studied to consider their industrial transformation feasibility. All the varieties were checked to ensure fulfilment of the characteristics of each kind according to the NIVAP. The following determinations were made: reducing sugars, dry matter, aptitude for frying in olive oil and sunflower and colours, yield, absorption of lipids and resistance to browning in raw and cooked. The industrial demands are: oval-extended shape, greater diameter of 55 mm, reducing sugars < 2.5 g/kg, dry matter > 200 g/kg, and resistance to browning. Only Agria fulfilled all the established requirements. Désirée and Kennebec were not resistant to browning of raw mashed potatoes and Europa and Stemster had a dry matter lower than the required for the industries, obtaining the worse yields and the greater percentage of retained fat. Resumen Se estudió la aptitud para la transformación industrial de 6 variedades de patata (Agria, Désirée, Europa, Hérmes, Kennnebec y Stemster) producidas en Xinzo de Limia (Ourense). Para ello se comprobó el cumplimiento de las características varietales del NIVAP y se realizaron las siguientes determinaciones: azúcares reductores; materia seca; aptitud para frito en aceite de oliva y girasol midiendo el color final, rendimiento, absorción de lípidos y evaluación del oscurecimiento del puré crudo y cocido. Los requisitos exigidos por la industria son: forma oval-alargada, calibre mayor de 55 mm, azúcares reductores < 2,5 g/kg, materia seca > 200 g/kg y resistencia al oscurecimiento en crudo y cocido. Solamente Agria cumplió todas las exigencias establecidas. Désirée y Kennebec resultaron sensibles al pardeamiento en crudo y Europa y Stemster presentaron valores de materia seca inferiores a los exigidos, los rendimientos más bajos y el porcentaje de grasa retenido más alto. Palabras clave: Patatas, transformación industrial, azúcares reductores, fritura