Aplicação de campos elétricos pulsados de alta intensidade no processamento de suco de cenoura

• Autor(a) principal: Teixeira, Luciano José Quintão
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/396
• topic: Suco de cenoura; Campo elétrico pulsado; Pasteurização; Carrot juice; Pulsed electric field; Pasteurization; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::TECNOLOGIA DE ALIMENTOS

Vegetable juice is a product of high nutritional value, however it is perishable and for that during your processing needs to pass for a stabilization process to increase your shelf life. Thermal treatment is usually used with this purpose; however it causes nutritional loss, flavor, aroma, appearance and texture alteration. Like this, in the last years, non-thermal treatments have been studied, among them, high intensity pulsed electric fields (HIPEF). HIPEF can stabilize vegetables juices with a minimal alteration of its properties (sensorial and nutritional). This work was divided in two stages. In a first moment it was determined the conditions of HIPEF stabilization (field intensity; width, frequency and polarity of pulses; and total treatment time) that achieved a better stabilization of carrot juice taking as answer variable peroxidase inactivation and color preservation. They were still made physical-chemical characterization of carrot juice and it was proposed some models to explain the enzymatic inactivation as a function of treatment time or electric field intensity applied. The different models used fit well and the model of first fractional order presented a better accuracy. In a second moment, it was made a comparative study among the pasteurization efficiency of HIPEF and two thermal treatments commonly employees by vegetable juices industry. The comparison was made just after process and also throughout storage time taking as answer variable some bioactive compound (&#946;-carotene, vitamin C and phenolics compound), sensorial analysis, enzymatic inactivation and some physical-chemistries properties. The HIPEF treatment using 35 kV/cm of field intensity, applying 6 &#956;s pulse width in bipolar mode at 200 Hz of frequency during 1500 &#956;s was selected as being more effective on carrot juice stabilization. The HIPEF treated carrot juice presented a better sensorial acceptance; higher cloudy stability, and more retention of vitamin C than that presented by juices thermally processed. There was no significant difference (p < 0.05) among treatments for pH value, solids soluble content, viscosity and antioxidant capacity. The concentration of &#946;-carotene increased after process for all treated juices and no significant differences (p < 0.05) among them were observed. The tenor of &#946;-carotene, vitamin C and antioxidant capacity depleted exponentially as a function of storage time. Carrot juice did not present lypoxygenase activity and the pH reduction was enough to inhibit polyphenoloxidase. Pectin methyl esterase was completely inhibit for all treatments applied and peroxidase presented low residual activity after HIPEF and thermal treatments having no significant differences (p < 0.05) among them. It was ended that the HIPEF process was capable to promote carrot juice stabilization with smaller alteration of its properties and smaller nutritional losses. Therefore, HIPEF is better than thermal treatment to stabilize and to promote high quality of carrot juices.