a b s t r a c tThe aim of this paper was to evaluate the effectiveness of the quick tests Viscofrit, Testo 265 and Fricheck in the monitoring of used frying oil for discarding, as a substitute for the measurement of total polar compounds (TPC), indicating the advantages and disadvantages of each test. Fifty-nine frying oil samples used to fry different types of food were evaluated using quick tests and the TPC open-column conventional method. The samples presented TPC values from 6.0 AE 1.1% to 39.2 AE 1.0%. Testo 265 was correlated to the conventional method by the equation: y ¼ 0.89x þ 4.0 (r ¼ 0.90), with a 5% level of significance. A correlation factor of 0.9 (a ¼ 0.05) was essential for these results, since water in the food increases the TPC values. Viscofrit provided results consistent with the open-column method for 78.8% of the samples, with 9.3% of false positive results. Testo 265 and Viscofrit showed good results for the substitution of the TPC conventional method, respecting their limitations. Viscofrit is not recommended for high melting point samples.

Resumo -O objetivo deste trabalho foi recuperar e fracionar as proteínas do soro de leite por meio da técnica de coacervação, utilizando o polissacarídeo carboximetilcelulose sódica (CMC). O soro de leite foi obtido da fabricação industrial do queijo tipo frescal. Foram estudados concentrações do polímero (0,1% a 0,9% CMC p/v) e valores de pH, a fim de se obter uma precipitação seletiva das proteínas do soro de leite, sendo as condições otimizadas para produção em piloto. Mediante ajuste gradual, foi possível obter, no pH 3, uma precipitação das proteínas totais (PT/CMC); no pH 4, da β-lactoglobulina (β-Lg/CMC) e, no pH 3,2, a maior proporção de α-lactoalbumina (α-La/CMC). Os coacervados foram separados, por aplicação de força centrífuga, e caracterizados em relação à composição centesimal e perfil eletroforético. O maior rendimento foi verificado no fracionamento da β-lactoglobulina, com 86% de recuperação dessa classe de proteínas do soro desnatado. O coacervado β-lactoglobulina-CMC (β-Lg/CMC) apresenta maior conteúdo protéico, provavelmente em conseqüência da proporção estabelecida entre os hidrocolóides coacervados. O coacervado composto pela α-La/CMC apresentou menor conteúdo protéico e porcentagem de recuperação dessas proteínas presentes no soro.Termos para indexação: carboximetilcelulose, β-lactoglobulina, α-lactoglobulina, hidrocolóides coacervados. Milk whey protein recuperation by coacervation with polysaccharideAbstract -This work aimed to recover and fractionate milk whey proteins through the coacervation technique, using sodium carboxymethyl cellulose (CMC) polysaccharide. Milk whey was obtained from the manufactured cheese type "frescal". Polymer concentration (0.1-0.9% CMC w/v) and pH values were studied in order to obtain a selective precipitation of whey proteins; conditions were optimized to pilot scale production. After pH gradual adjustment the precipitation of total proteins (PT/CMC) was achieved for pH 3; for pH 4 β-lactoglobulin (β-Lg/CMC) precipitation and for pH 3.2 the greatest proportion of α-lactoalbumin (α-La/CMC) precipitation. Coacervates were separated by centrifuge force, and characterized in relation to their composition and electrophoretic profile. The highest yield was obtained from fractionation of β-Lg/CMC with precipitation of 86% of this whey protein type. Highest protein content was showed by β-Lg/CMC, probably due to the proportion among hydrocolloids. The α-La/CMC showed minor protein content and yield recuperation of this whey protein fraction.

No abstract

No abstract

No abstract