Precipitation Of Whey Proteins Research Articles

Simple utilization of lactic acid whey in dairy processing

Abstract The use of ultra-filtered lactic acid whey retentate was investigated for the making of sour cream. The utilization of lactic acid whey is limited due to its special properties, so the logical utilization way is to use it in fermented products. First, we concentrated lactic acid whey collected from cottage cheese making by ultrafiltration (UF), then UF Whey Retentate (UFWR) was added (by 2, 5, and 10%) into fat standardized cream for sour cream making. We investigated the texture and sensory properties of the sour cream samples compared with the industrial products. Generally, we can state that the use of small portion of UF whey retentate did not result noticeable changes and did not reduce the sensory value of sour creams. Higher UF whey retentate addition improved some texture properties of experimental samples, but the summarized evaluation of UFWR addition was not unequivocal. Control samples showed better results. Based on our results, the sample, which contained 5% UF whey retentate, had good texture and acceptable sensory properties. Furthermore, more than 5% UF lactic acid whey retentate (coming from our own ultrafiltration process) resulted remarkably worse sensory properties than the other samples. Further investigation is needed to find the optimal composition and sensory properties of UFWR. Furthermore, we have to perform technological investigation to reach a higher concentration factor using pre-treatment of whey and to avoid the precipitation of whey proteins during the high temperature pasteurization of cream, cream mixed with UFWR or diafiltered whey retentate. We guess that the use of one-stage diafiltration would already decrease the unfavourable sensory properties of lactic acid whey retentate.

Whey protein mouth drying influenced by thermal denaturation

Whey proteins are becoming an increasingly popular functional food ingredient. There are, however, sensory properties associated with whey protein beverages that may hinder the consumption of quantities sufficient to gain the desired nutritional benefits. One such property is mouth drying. The influence of protein structure on the mouthfeel properties of milk proteins has been previously reported. This paper investigates the effect of thermal denaturation of whey proteins on physicochemical properties (viscosity, particle size, zeta-potential, pH), and relates this to the observed sensory properties measured by qualitative descriptive analysis and sequential profiling. Mouthcoating, drying and chalky attributes built up over repeated consumption, with higher intensities for samples subjected to longer heating times (p<0.05). Viscosity, pH, and zeta-potential were found to be similar for all samples, however particle size increased with longer heating times. As the pH of all samples was close to neutral, this implies that neither the precipitation of whey proteins at low pH, nor their acidity, as reported in previous literature, can be the drying mechanisms in this case. The increase in mouth drying with increased heating time suggests that protein denaturation is a contributing factor and a possible mucoadhesive mechanism is discussed.

Improvement of fermentative decolorization of olive mill wastewater by Lactobacillus paracasei by cheese whey's addition

The effect of the cheese whey's (CW) addition on the fermentative decolorization of olive mill wastewater (OMW) by Lactobacillus paracasei, with and without pH adjustment by lime, was investigated. Mixtures OMW/CW at different proportions were fermented. The highest colour removal (47%) and total phenolic reduction (22.7%) of OMW were obtained after cofermentation of OMW/CW at proportions of 10/90, respectively. The decrease of pH after cofermentation of the two wastewaters, induced the precipitation of whey proteins with phenolic compounds and, so, improves decolorization. These removal yields reached 64% and 34%, respectively after precipitation by adjustment of pH at 7 with lime at the end of cofermentation. These improvements were correlated to a clarification of wastewaters by precipitation of whey proteins with phenolic compounds. An enhanced decolorization (up to 93%) and a total phenolic reduction (50%) of the mixture were obtained when cofermentation sequentially pH corrected by lime addition was investigated.

Recuperação de proteínas do soro de leite por meio de coacervação com polissacarídeo

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 beta-lactoglobulina (beta-Lg/CMC) e, no pH 3,2, a maior proporção de alfa-lactoalbumina (alfa-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 beta-lactoglobulina, com 86% de recuperação dessa classe de proteínas do soro desnatado. O coacervado beta-lactoglobulina-CMC (beta-Lg/CMC) apresenta maior conteúdo protéico, provavelmente em conseqüência da proporção estabelecida entre os hidrocolóides coacervados. O coacervado composto pela alfa-La/CMC apresentou menor conteúdo protéico e porcentagem de recuperação dessas proteínas presentes no soro.

Heat induced gelation of acid milk: balance between weak and covalent bonds.

Gelation of acidified milk at pH[ges ]5, after heat treatments is a well known phenomenon, due to the precipitation of whey proteins, and especially β-lactoglobulin onto κ-casein (Sawyer, 1969). High heat treatments cause denaturation of whey proteins which associate with κ-casein through disulphide interchange reactions (Hill, 1989). Since their charge is reduced, the denatured proteins associated with casein micelles become susceptible to aggregation when milk is then acidified, which promotes enhanced protein–protein interactions (Lucey et al. 1997). The gelation phenomenon involves disulphide bonds (Hashizume &amp; Sato, 1988; Goddard, 1996) which are responsible for the gel firmness (Goddard, 1996). However, other interactions between proteins can occur, such as hydrogen and hydrophobic bonds, especially at the initial stage of interactions (Haque et al. 1987; Haque &amp; Kinsella, 1988; Jang &amp; Swaisgood, 1990). It is therefore relevant to investigate a possible contribution of weak linkages to the gel structure and firmness.

Heat Precipitation of Whey Proteins

Heat Precipitation of Whey Proteins

Selective Precipitation of Whey Proteins with Ferric Chloride

Selective Precipitation of Whey Proteins with Ferric Chloride

The precipitation of whey proteins by carboxymethyl cellulose of differing degrees of substitution;.

SummaryThe complexing of whey proteins in hydrochloric acid whey by carboxymethyl cellulose (CMC) has been studied. The efficiency of precipitation of CMC (the ability to form insoluble complexes with whey proteins) increased with increasing degree of substitution (DOS) of CMC. At a DOS of greater than 1·4, efficiencies of precipitation of whey protein greater than 90% were achieved without the need for dilution of whey. CMC of high DOS would thus be useful in whey protein reclamation schemes. The amount of CMC necessary for maximum efficiency of precipitation also increased with increasing DOS. The composition of the CMC-protein complex varied little over the range pH 2·8–4·0. Under optimum conditions for binding, the complex contained 61–68% protein and more than 95% of the CMC originally in solution was precipitated in the complex.

Selective Precipitation of Whey Proteins with Carboxymethylcellulose

Anionic hydrocolloids undergo pH-dependent interactions with whey proteins. A partial fractionation of carboxymethylcellulose/protein complexes was achieved by selected conditions of pH, ionic strength, and ratio of carboxymethylcellulose to protein. A rapid screening method determined the amount of carboxymethylcellulose required. β-Lactoglobulin and bovine serum albumin were complexed at, pH 4 by adding a predetermined amount of carboxymethylcellulose solution to whey, cooling the mixture to 2C and collecting the precipitate by centrifugation (yield : 5.1 g/liter, CMC/protein ratio : 0.28). A second complex containing α-lactalbumin was precipitated by adjusting the supernatant to pH 3.2 and adding a controlled amount of carboxymethylcellulose at 2C (yield: 0.7 g/liter of remaining supernatant, CMC/protein ratio : 0.48). After removal of this complex by centrifugation the supernatant was adjusted to pH 7.5 which coprecipitated proteins (apparently proteose-peptones) along with calcium phosphate salts (yield of freeze-dried, dialyzed product: 0.1 g/liter, CMC/protein ratio: 0.05). With a combination of CMC treatment of whey at pH 4.0 and ammonium sulfate precipitation at pH 6.6, α-lactalbumin and immunoglobulins were recovered free of carboxyrnethylcellulose.