RESUMO

Whey is a by-product that represents a cheap source of protein with a high nutritional value, often used to improve food quality. When used as a raw material to produce hypoallergenic infant formulas (HIF), a processing step able to decrease the allergenic potential is required to guarantee their safe use for this purpose. In the present paper, thermal treatments, high hydrostatic pressure (HHP), and enzymatic hydrolysis (EH) were assessed to decrease the antigenicity of whey protein solutions (WPC). For monitoring purposes, a competitive ELISA method, able to detect the major and most allergenic whey protein ß-lactoglobulin (BLG), was developed as a first step to evaluate the efficiency of the processes. Results showed that EH together with HHP was the most effective combination to reduce WPC antigenicity. The evaluation method proved useful to monitor the processes and to be employed in the quality control of the final product, to guarantee the efficiency, and in protein antigenicity reduction.

RESUMO

BACKGROUND: The suitability of commercial peaches for minimal processing (MP) is limited, mainly due to shortened shelf-life. Gamma irradiation has emerged in MP fruits as a promising technology. This study aimed to investigate the effects of gamma irradiation on the sensory and metabolic profiles of MP peaches from two cultivars - 'Forastero' (FT) and 'Ruby Prince' (RP) - and evaluate the relationship between both profiles. MP peaches were packaged and divided into two groups: one without additional treatment (K) and the other subjected to gamma irradiation (1.0 kGy, I- irradiation treatment), making a total of four samples (FTK, FTI, RPK and RPI). The sensory profile was carried out by an assessor panel. Metabolite analysis was accomplished by gas chromatography-mass spectrometry. RESULTS: Irradiation significantly affected color, homogeneity, peach aroma, total flavor intensity, peach flavor, sweetness and juiciness in FT, increasing their intensities. In the RP cultivar, irradiation increased brightness, total aroma intensity, peach aroma, and flavor and texture descriptors. Regarding metabolites, only malic acid and sucrose increased their concentrations in the irradiated samples. Partial least squares showed that sucrose was mainly correlated with sweet, total aroma intensity and peach flavors, and linked with FTI sample. Bitter along with peach aroma and total intensity flavor were associated with RPI sample. CONCLUSION: The applied dose accelerated the ripening process of the peach. The study highlights the importance of complementing sensory analysis with metabolomics tools to optimize fruit quality in minimally processed peaches. © 2023 Society of Chemical Industry.

Assuntos

RESUMO

Heat shock proteins (HSP) are synthesized in living tissues exposed to transient increase in temperature and play a central role in the protective response against heat and other stresses. In fruits, this response to heat treatment provides resistance to a physiological alteration known as chilling injury. Despite the physiological importance of this group of proteins, publications comparing different methodological alternatives for their analysis are rather scarce. In the present paper, we conducted a comparative study using different electrophoretic and immunological techniques to evaluate the HSP response in fruits. Proteins were extracted from tomato fruit exposed to an HSP-inducing temperature (38 °C) for different times (0, 3, 20, and 27 h). Different alternatives of analysis (SDS-PAGE, SDS-PAGE followed by IEF, Western blot, and dot blot) were performed, and their potential application discussed. The study was complemented with a practical application, in which tomatoes were subjected to heat and anaerobic treatments and then stored in a chill-inducing temperature. This application evidences the relevance of knowing the level of proteins attained by stress treatments which correlates with the acquired tolerance.

RESUMO

The presence of milk, egg and soy proteins was evaluated in thirteen commercial products, which were premixes to make cream caramel, cake, soy "milanesas", "tortas fritas", pizza, gnocchi and complementary foods. Samples were analysed using SDS-PAGE, immunoblotting and ELISA methods. The electrophoretic method and immunoblotting were useful to confirm the presence of milk, egg and soy proteins in four samples that declared them as ingredients. In other samples, both methods showed negative results for some of these proteins, although they were also declared as ingredients. This suggests that those proteins were not added as ingredients in these products. The ELISA kits detected very low concentration of the allergenic proteins in four products with precautionary phrases and also in five samples that made no reference to them in their labels. ELISA methods are useful to detect cross contamination due to their high sensitivity. The food industry should be responsible for the declaration of milk, egg and soy proteins in their food labels.

Se evaluó la detección de proteínas de leche, huevo y soja en trece productos comerciales, correspondientes a premezclas para preparar flanes, bizcochuelo, milanesas de soja, tortas fritas, pizza, ñoquis y productos en polvo a base de harinas para niños pequeños. Las muestras fueron analizadas por SDS-PAGE, inmunoblotting y métodos de ELISA. El método electroforético e inmunoblotting resultaron útiles para confirmar la presencia de las proteínas alergénicas en algunas muestras que las declaraban como ingredientes. En cuatro muestras que también declaraban como ingredientes alguna de estas proteínas, tanto con SDS-PAGE como con Inmunoblotting, los resultados fueron negativos, sugiriendo que dichas proteínas no fueron agregadas como ingredientes en dichos alimentos. Los kits de ELISA permitieron la detección de concentraciones muy bajas de estos alérgenos en cuatro productos que presentaban frases de advertencia e incluso en otros cinco que no tenían ninguna declaración de alérgenos. Los métodos de ELISA son útiles para detectar contaminaciones cruzadas, dada su elevada sensibilidad. Se concluye que resulta necesario una declaración responsable de estas proteínas alergénicas, en los rótulos de este tipo de alimentos por parte de los fabricantes.

Assuntos

RESUMO

In recent years, heat treatment has been used to prevent the development of chilling injury in fruits and vegetables. The acquired tolerance to chilling seen in treated fruit is related to the accumulation of heat shock proteins (HSPs). The positive effect of heat treatment has generally been verified for only a narrow range of treatment intensities and more reliable methods of determining optimal conditions are therefore needed. In this regard, quantitation of HSPs would seem to be an interesting tool for monitoring purposes. As a step toward the development of analytical methodology, the objective of this study was the isolation and characterization of relevant HSPs from plant tissues. Tomato fruits were exposed to a temperature of 38 degrees C for 0, 3, 20 and 27 h, and protein extracts from pericarp were analysed using SDS/PAGE. Analysis revealed the appearance of an intense 21 kDa protein band in treated samples. IEF of this band showed the presence of four major proteins (HSPC1, HSPC2, HSPC3 and HSPC4) with similar pI values. A monospecific polyclonal antiserum was raised in rabbits against purified HSPC1 protein, which cross-reacted with other small heat shock proteins. The major proteins were characterized by MS/MS analysis of tryptic peptides, all having blocked N-termini. The antiserum obtained proved suitable for detecting increased amounts of small heat shock proteins in tomatoes and grapefruits subjected to heat treatment for 24 and 48 h; these treatments were successful in preventing the development of chilling injury symptoms during cold storage. Our data are valuable for the future development of analytical methods to evaluate the optimal protection induced by heat treatment in different fruits.

Assuntos