RESUMO
The heat and momentum transfer of tomato puree through a concentric-tube heat exchanger over a range of generalized Reynolds number (0.05 < Re < 66.5) was experimentally and numerically analyzed. Thermophysical and rheological properties of tomato puree (12°Brix) were measured from 20 to 60°C. The velocity, pressure, and temperature were calculated using the computational fluid dynamics (CFD) software FLUENTTM with temperature-dependent transport properties. The thermal operation of the concentric-tube exchanger was satisfactorily predicted using CFD, indicating accurate measurement of tomato puree properties with temperature variations. A concordance was found between the calculated Fanning friction factor and generalized Reynolds with the experimental correlation. A modified Sieder-Tate correlation was established, which allows properly expressing the Nusselt number as a function of the Peclet number. Simple correlations for the mechanical work and the heat transfer rate as a function of the volumetric flow rate were derived. The thermal efficiency was high at low puree flow rates but decreased with higher rates. However, at high flow rates, ceased its decline, instead showing a slight improvement. The analysis confirmed higher heat transfer rates in the concentric-tube heat exchanger compared to a plain tube at low puree flow rates. The results offer valuable insights for assessing diverse operational conditions in dairy, beverage, sauce, and concentrated food industries. Additionally, they also enhance the analysis and design of concentric-tube heat exchangers. PRACTICAL APPLICATION: The knowledge of the rheological and hydrodynamical behavior of fluids in concentric-tube heat exchangers allows to explore a set of different operating conditions to improve the yield and effectiveness on the system heating/cooling design.
RESUMO
As pesquisas com tomate e seus produtos têm sido intensificadas pela associação entre os carotenóides com função antioxidante, principalmente o licopeno, e a redução no risco de doenças crônicas, como o câncer de próstata. As cenouras são principais fontes de origem vegetal de carotenóides provitamínicos A (caroteno). O objetivo deste trabalho foi elaborar molho concentrado à base de tomate e cenoura e avaliar características físico-químicas e teores de carotenóides presentes no produto final. Destaca-se que o produto apresentou teor de 21,9 Brix. Análise da composição centesimal permite avaliar que não houve diferenças significativas entre o produto desenvolvido e os molhos convencionais. O teor de carotenóides dos cloroplastos foi elevado (14,90 g/g), em comparação com produto convencional à base de tomate (teor de 2,19 g / 100g). Registra-se a importância de estudos complementares para caracterização dos tipos de carotenóides presentes no produto elaborado.(AU)
Over the past few years, research regarding tomato and tomato products has been intensified by the association between carotenoids and antioxidant function, mainly the lycopene. and reduced risks of chronic diseases, such as prostate cancer. Carrots are the main vegetable source of carotenoids Pro vitamin A (a and B carotene). The objective of this paper was to develop a tomato purée using tomato and carrots, as well as to evaluate physical-chemical characteristics and carotenoid levels in the finished product. The tomato and carrot purée presented a 21.90 Brix. A centesimal composition analysis allowed assessing that there were no significant differences between the developed product and conventional tomato purée. A high chloroplasts carotenoid level (14,90µg/g) has been observed, compared with similar marketed products using only tomato (2,19µg/g).The importance of complementary works that characterize carotenoid types presented in the developed product has been highlighted. (AU)
Assuntos
Análise de Alimentos , Concentrados de Tomates , Daucus carota , Antioxidantes , Fenômenos Químicos , Carotenoides , Tabela de Composição de Alimentos , Alimentos Industrializados , Solanum lycopersicum/efeitos adversosRESUMO
Foram analisadas 152 amostras de extrato de tomate, purê de tomate e catchup, para averiguar sua qualidade, através da pesquisa de sujidades pelo método de extração em frasco de Wildman. As sujidades encontradas foram: fragmentos de insetos, fragmentos de larvas, larvas, ovos e nematóides. Concluiu-se que a maior percentagem de contaminação ocorreu em amostras que apresentavam somente fragmentos de insetos, com 61,2% para extratos de tomate, 58,1% para purês de tomate e 61,8% para catchups. Os resultados obtidos sugerem a necessidade de modificação na legislação brasileira, estabelecendo limite de tolerância para fragmentos de insetos, e maior controle de qualidade, por parte das indústrias, dos produtos à base de tomate (AU).