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Chemical and physical properties of aloe vera (Aloe barbadensisMiller IntroductionAloe vera (Aloe barbadensis Miller) is a perennial plant of the Xanthorrhoeaceae family (UNITED…, 2012). It is also placed by most sources in the Liliaceae family although it has been designated its own family, known as Aloeaceae (ESHUN;HE, 2004). Aloe vera is well known for its succulent leaves and the medicinal and cosmetic properties of the gel obtained from them. It is widely cultivated around the world, but has escaped from cultivation and become naturalized in the warm regions of the Mediterranean, Northern Africa, the Indian subcontinent, South America, and the Caribbean, which makes it quite difficult to correctly establish its origin. It is supposed to be native to North Africa or the Nile region in Sudan (BOZZI et al., 2007). The genus Aloe contains over 400 different species, and Aloe barbadensis, Aloe arborescens, and Aloe chinensis are the most popular. Aloe barbadensis Miller is considered the most biologically active species (BOZZI et al., 2007). Aloe latex and aloe gel are two products that can be separated from the plant (REYNOLDS; DWECK, 1999). The leaf parenchyma (aloe gel) is colorless and tasteless, and has been used particularly in the treatment of skin diseases (OKAMURA et al., 1996). The gel consists primarily of water (> 98%) and polysaccharides such as pectin, cellulose, hemicellulose, glucomannan, acemannan, ResumoO objetivo deste estudo foi avaliar o efeito da aplicação de altas pressões hidrostáticas (150, 250, 350, 450 e 550 MPa) aplicadas durante 5 minutos sobre a atividade antioxidante, concentração de polifenóis totais, cor, firmeza, taxa de reidratação e capacidade de retenção de água do gel de aloe vera armazenado durante 60 dias a 4 °C. As propriedades analisadas do gel pressurizado mostraram mudanças significativas depois de armazenadas. Para pressões de 550 Mpa, registrou-se o maior aumento de polifenóis totais. No entanto, observou-se uma diminuição da capacidade antioxidante em todas as amostras, em comparação com a amostra não tratada (p < 0,05). As alterações de cor foram menores para pressões entre 150 e 250 MPa. A aplicação de altas pressões hidrostáticas diminuiu a firmeza do gel, registrando-se o menor valor para 150 MPa (p < 0,05). Por outro lado, o tratamento sem pressão mostrou uma maior perda de firmeza, indicando que o tratamento por altas pressões conserva esta propriedade. A aplicação de altas pressões evidenciou modificações da matriz do alimento, avaliadas como taxa de reidratação e capacidade de retenção de água. Palavras-chave: capacidade antioxidante; polifenóis totais; qualidade; aloe vera. AbstractThe aim of this study was to evaluate the influence of high hydrostatic pressure (150, 250, 350, 450, and 550 MPa), applied for 5 minutes, on antioxidant capacity, total phenolic content, color, firmness, rehydration ratio, and water holding capacity of aloe vera gel stored for 60 days at 4 °C. The analyzed properties of the pressurized gel showed significant changes after the st...

The aim of this work was to study the effect of high hydrostatic pressure (HHP) on colour, dietary fibre, vitamin C content, polysaccharides content, physicochemical and structural properties of aloe vera gel at three pressure levels (300, 400 and 500 MPa for 3 min) after 35 days of storage at 4±1°C. The results showed that HHP exerted a clear influence on most of the quality parameters studied. Moisture, protein and fat contents did not show changes with an increasing pressure. Ash, crude fibre and carbohydrates content increased with increasing pressure. Vitamin C content did not show significant differences after 35 days of storage. The variation of colour in the samples increased at 500 MPa. Total dietary fibre, water holding capacity and firmness increased with pressure. However, all HHP-treated samples presented a decrease in hydration ratio and polysaccharides content; and also minor alterations in the structural properties were produced at HHP of 300-500 MPa, resulting in a high quality gel.