Table 1. Mean values of water activity and main compounds in the Thompson 2 seedless grape variety before and after each drying treatment. In parenthesis is the 3 standard deviation. 4 5 Table 2. Mean values of water activity and main compounds in the Imperial 6Seedless variety before and after each drying treatment. In parenthesis is the 7 standard deviation. 8 9 Table 3. Mean values of water activity and main compounds (referred to fresh 10 fruit mass) of the two varieties of grapes dried by the two drying treatments. In 11 parenthesis is the standard deviation. 6 Abstract: 7The close relationship between the consumption of fruits and health status stems from 8 the nutritional and non-nutritional compounds found in fruits which play a key role in 9 the prevention of different diseases. However, fruit processing and storage greatly affect 10 fruit compounds. The aim of the present work was to study the influence of processing 11 on the stability of macro and micronutrients present in grapes, with a view to 12 recommending products that provide the highest nutritional quality and the best health 13 conditions. The study focused on fruit dehydration treatments. Conventional and 14 microwave-assisted air-drying processes were used to obtain raisins. Dehydration 15 caused a decrease of all grape compounds studied excluding total phenols. Moreover, 16 compared to conventional processing, microwave-assisted drying produced greater 17 losses of ascorbic acid in the grape and increased pectin solubilization with a 18 consequent change in texture. However the microwave-dehydrated samples showed 19 higher antioxidant activity. 20 21

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La miel de abeja se ha utilizado desde la antigüedad por sus buenas propiedades nutricionales y terapéuticas. Se produce en todo el mundo y juega un papel importante como agente antioxidante, antiinflamatorio y antibacteriano; también aumenta la adherencia de los injertos de piel y el proceso de curación de heridas. La relación entre el consumo de ciertos alimentos y la salud deriva de la presencia en éstos de una serie de sustancias nutritivas y otras no nutritivas, pero con un papel clave en la prevención de determinadas enfermedades. Los polifenoles son compuestos bioactivos que se encuentran en los alimentos, contribuyen a mejorar diversas actividades fisiológicas, desempeñando un papel antimicrobiano, con propiedades antinflamatorias, antitumorales y anticancerígenas. El objetivo de esta investigación fue determinar la actividad antioxidante y el contenido fenólico total de miel de abeja producida en Zacatecas. Se analizaron cuatro variedades de miel de abeja [multiflora, mezquite (Prosopis laevigata), flor de gatuño (Mimosa spp.) y flor de gatuño cremosa (Mimosa spp.)] en términos de capacidad antioxidante (métodos ABTS•+, DPPH y FRAP) y el contenido fenólico total (método Folin-Ciocalteau) por dos procedimientos de extracción (extracción metanólica y acuosa). Los datos se sometieron a análisis de varianza de una vía. Se encontraron diferencias estadísticamente significativas (P ≤ 0.05) entre las muestras en términos de contenido fenólico total, pH, °Brix y humedad, así como en la capacidad antioxidante por los métodos ABTS•+ y FRAP. La extracción metanólica mostró el contenido fenólico más alto (144 mg of GAE 100 g-1), mientras que la extracción acuosa presentó la mayor capacidad antioxidante cuando fue analizada con el método DPPH (1118.3 μmol equivalentes de Trolox 100 g-1).

This paper studies the effects of conventional and microwave blanching on grapes that are being processed for storage in syrup. An analysis was made of the blanching effects on macro‐ and micronutrients, as well as on color and mechanical properties. To test the effectiveness of these blanching treatments, enzymatic residual activity was measured for polyphenol oxidase, peroxidase and pectinmethylesterase. Both blanching treatments reduced enzyme activity in the grapes, especially polyphenol oxidase (99%). Blanching treatments also caused significant decrease in tartaric acid (TA) also as in color and mechanical changes, more marked in conventional‐treated samples. As for the effect of storage, microwave treatment supposed a greater stability of TA and total phenols than conventional one, also as a greater antioxidant activity of grapes. From this point of view, microwave treatment of samples immersed in water can be proposed as a good alternative to conventional heating in boiling water for grapes blanching. PRACTICAL APPLICATIONS Blanching is a relatively mild treatment, which aims to inactivate enzymes that would cause a decrease of final product quality. The microwave energy has attracted considerable interest because of the penetration capacity of waves, heating not only the food surface but also the inner part. This speeds up the drying process and contributes to improve the quality of the product. The results of this study showed that microwave blanching of grapes when immersed in water has advantages as compared with conventional treatment. Enzyme inactivation achieved with this kind of energy was very similar in both cases, but microwave treatment supposed a greater stability of tartaric acid and total phenols than conventional one, also as a greater antioxidant activity of grapes.