Formulación de mermelada de fresa con polvo de piel mandarina: efecto sobre las propiedades físico-químicas y la estabilidad microbiológica

Abstract

[EN] Food industry (Agro-food industry) is aware of the need to manage the produced wastes in a correct way. Its aim is to reincorporate those residues to the food chain whenever possible, to obtain products with added value in a sustainable way and to contribute to the circular economy of the sector. The main objective of this assignment was to evaluate the effect of incorporating the mandarin skin powder as a functional ingredient for formulated strawberry jam. For that purpose, the physicochemical, antioxidant and sensorial properties were determined, as well as the microbiological stability in formulated jams with different powder proportions (0; 0.2 and 5g/100g of fruit) after being elaborated and after storage period divided into one month kept in ambient temperature and from three to six weeks of accelerating aging getting 37 degrees. Those jams which were elaborated showed their physicochemical values within the set limits by the Royal Degree 670/1990, appearing significant differences only in function of aging storage. The addition of powder meant an increase in the amount of phenols and flavonoids. However, the total anthocyanins content and total antioxidant capacity decreased when the powder amount increased. The accelerated aging involved a decrease in the antioxidant properties of jam, possibly due to the thermal sensitivity of these compounds. As far as optical and mechanical properties are concerned, a range of important changes were showed between different samples which were more notorious regarding to the storage period of time than to the powder concentration added. Focusing on the microbiological analysis, it can be checked that the addition of mandarin skin powder, limits the microbiological growth, confirming its preservative power. The sensorial analysis highlighted that the jam with no added powder was the best valued by tasters, followed by those elaborated with 5 and 2.5g of powder/ 100g of fruit. On the other hand, the purchase willingness of the surveyed tasters, improved significantly among those products with we considered healthier. As a final conclusion, the mandarin skin powder may have several applications in the food industry as a functional ingredient, since the improvement of the microbiological stability until the increase of the antioxidant capacity in spreadable products or jams made by low content fruits in this type of compounds.

[ES] El objetivo de este trabajo final de grado es evaluar el efecto que la adición de polvo de piel de mandarina en diferentes concentraciones a la formulación de mermelada de fresa ejerce sobre sus principales propiedades físico-químicas y microbiológicas. Entre las propiedades físico-químicas, se analizarán la humedad, la actividad del agua, el contenido en sólidos solubles, el color, la textura y propiedades antioxidantes, tales como el contenido en fenoles y flavonoides totales, el contenido en antocianinas monoméricas y la capacidad antioxidante por diferentes métodos (DPPH y ABTS). En cuanto a la estabilidad microbiológica, se evaluará el contenido en mohos y levaduras, así como el de mesófilos aerobios. Todas estas determinaciones se llevarán a cabo sobre el producto recién elaborado y a lo largo de su almacenamiento durante un máximo de 12 meses. También está prevista la realización de ensayos de aceptación con las formulaciones que presenten mejores atributos. Es de esperar que la incorporación de polvo de piel de mandarina a la formulación de mermelada de fresa dé como resultado un producto con propiedades antioxidantes mejoradas y que sea más resistente a la proliferación de microorganismos responsables de deterioro.