Abstract. The purpose of this paper was to see what effects microwaves have on the physical-chemical composition of the raw milk. The results showed that the averages of fat, protein, dry substance and lactose concentrations decreased during the microwave exposure while the density averages increased. This variation was characterized by the critical time moment of 31.71 s, corresponding to the moment when a milk sample exposed to the microwaves action undergoes the first more significant alteration of its physical-chemical composition. (doi: 10.5562/cca1785)
The effects of microwave-assisted extraction, ultrasound-assisted extraction and water bath extraction on the antioxidant activity of apple polyphenols are reported in this short communication. This study evaluated these methods based on their effect on the antioxidant activity of apple polyphenols whereas previous studies focused only on the yield rate of the extraction methods. The oxidation induction periods of apple polyphenols were 6.11, 3.26 and 1.13 h for microwave-assisted extraction, ultrasound-assisted extraction and water bath extraction, respectively. This result indicates that from the perspective of antioxidant activity protection microwave-assisted extraction is much better than the other two methods. Hopefully, this study could attract researchers' attention to the property of apple polyphenols in extraction and promote the development of natural polyphenols extraction methods.Keywords: extraction; apple pomace; polyphenols; antioxidant activity En esta comunicación corta se examinaron los efectos de la extracción asistida por microondas, la extracción asistida por ultrasonido y la extracción por baño de agua, en la actividad antioxidante de los polifenoles de la manzana. Este estudio evaluó estos métodos basándose en su efecto en la actividad antioxidante de los polifenoles de la manzana mientras que estudios previos se centraron únicamente en el índice de productividad de los métodos de extracción. Los periodos de inducción a la oxidación de los polifenoles de la manzana fueron 6,11, 3,26 y 1,13 h para la extracción asistida por microondas, la extracción asistida por ultrasonido y la extracción por baño de agua, respectivamente. Este resultado indicó que desde la perspectiva de protección de la actividad antioxidante, la extracción asistida por microondas es mejor método que los otros dos. Con suerte, este estudio podría atraer la atención de investigadores hacia las propiedades de los polifenoles de la manzana en la extracción y promover el desarrollo de métodos naturales de extracción de polifenoles.
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