Amaranthus and buckwheat protein concentrate effects on an emulsion-type meat product

The utilization of Amaranthus (five genotypes) and buckwheat protein concentrates in an emulsion-type meat product comprising beef lean, pork fat, salt and water was studied. 15% of the beef protein was replaced with the protein concentrates and the resulting meat emulsions were evaluated by thermorheology and thermal analysis. The cooking loss and physical properties of the meat gel were determined. The use of Amaranthus and buckwheat protein concentrates considerably affected both the emulsion and the cooked meat gel properties. The most favorable outcome was obtained with the buckwheat protein, which had similar effects to soy proteins. The Amaranthus protein concentrates generally did not give favorable results, although that derived from genotype K112 showed some positive effects. Correlation analysis showed that most of the observed variation in meat product properties could be explained by the emulsifying activity of the protein additive used. © 1998 Elsevier Science Ltd. All rights reserved.link_to_subscribed_fulltex

Properties of protein concentrates and hydrolysates from Amaranthus and Buckwheat

Protein concentrates and pepsin hydrolysates were made after isoelectric precipitation of the proteinaceous liquor from wet-milling of grain of five Amaranthus and one buckwheat genotype. The Amaranthus protein concentrates exhibited better solubility, foaming, and emulsification than two commercial soy protein controls. Many protein properties depend on solubility, and Amaranthus protein concentrates were more soluble than soy protein isolate. The buckwheat protein concentrate was highly soluble with excellent emulsification, but poor foaming ability. Partial pepsin hydrolysis further improved solubility of the protein concentrates and also altered their foaming property. Fractionation and subsequent characterization of protein concentrates revealed that glutelins, albumins, and globulins predominated, with prolamins present in minor quantity. SDS-PAGE showed that globulins and glutelins were comprised of several subunits with varying molecular weights from relatively high to low while albumins were mostly of low molecular weight. The prolamin fraction of the buckwheat concentrate was comprised of intermediate to low molecular weight subunits while those of Amaranthus concentrates were only of low molecular weight. This study demonstrated the feasibility of producing potentially useful functional protein concentrates as by-product of Amaranthus and buckwheat starch extraction.link_to_subscribed_fulltex

Effect of Amaranthus and buckwheat proteins on the rheological properties of maize starch

The relationship between pasting properties (determined with a Rapid Visco-Analyser) of maize starch and the texture of the resulting gel was examined after addition of Amaranthus and buckwheat proteins. An increase in the peak viscosity due to the addition of protein concentrates was observed, and a lesser increase from the addition of protein hydrolysates. The increase in starch pasting viscosity was related to protein solubility, and could be attributed to the starch granule stabilizing action of proteins. The interactions between starch and proteins were further investigated using oscillation and creep/recovery rheological tests. Generally, the proteins weakened starch gel structure, shown by the lower elastic modulus (G') and higher phase degree (δ) compared to gels without any proteins added. The same results were obtained from creep/recovery experiments. It seemed that, since native proteins interact more with the granules, they act as a barrier to the release of amylose molecules; hence the resulting gels became weak. If desired, such effects could be lessened by partially hydrolyzing the proteins. Copyright (C) 1999 Elsevier Science Ltd.link_to_subscribed_fulltex

Protein quality evaluation of Amaranthus wholemeal flours and protein concentrates

Based on the amino acid composition, Amaranthus seed protein is known to be of higher quality than most of the major cereal grains. However, protein quality does not solely depend on amino acid profile but also on its digestibility. In this study we determined amino acid composition and in vitro protein digestibility of wholemeal and isoelectric protein concentrates (IPC) from five Amaranthus genotypes. Factors most likely to influence protein digestibility such as heating and presence of antinutrients were studied. Heating increased protein digestibility in wholemeals but slightly decreased it in IPCs. Trypsin inhibitor level was negatively but weakly correlated to protein digestibility, and the level of polyphenolic compounds was negatively and significantly correlated to protein digestibility. A slight deficiency in leucine was noted for wholemeals and in lysine for IPCs. However, based on both in vitro digestibility and amino acid profile, Amaranthus proteins were confirmed to be of better quality than those of other cereals. © 1998 SCI

Effect of Amaranthus and buckwheat proteins on wheat dough properties and noodle quality

Isoelectric protein concentrates (IPC) were prepared from one buckwheat (Fagopyrum esculentum) and five Amaranthus genotypes. Their effect on the mixing properties of a wheat flour was studied. Mixograph and dynamic oscillatory measurements showed significant increases in dough strength with the addition of 2 and 4% IPC, correlated to the water-insoluble fraction level of the IPC. The same IPCs were used at 2% level to supplement a wheat flour in making Chinese dry noodles. Measurable changes in both the raw and cooked noodle color were observed, and the change caused by addition of buckwheat IPC was substantial. Some of the IPCs caused an increase in cooking loss and only one caused an increase in weight, while increase in volume of the cooked noodles was not significantly affected. The changes in the rheological properties of cooked noodles due to addition of IPCs were measured. Overall, their effects were favorable, but the changes were statistically significant in only a few cases. The substantial dough-strengthening effect of the IPCs was hence not effectively translated into improved cooked noodle quality, and possible reasons for this are discussed.link_to_subscribed_fulltex