Study of agricultural by‐products. Extractability and amino acid composition of grapeseed (Vitis vinifera) proteins

Abstract

The forecast f o r the year 2000 indicates a need to produce 164Experiments were conducted to measure the influence of the main variables in protein extraction (concentration, temperature, time, solid/liquid ratio and pH). Sodium hydroxide, sodium chloride and magnesium chloride aqueous solutions (of different ionic strength) and de-ionised water were used as extracting solvents.The results are reported in Table 1. In general, the most efficient extracting solution was aqueous NaOH. The water-extracted protein amounts were higher than those in salt solutions, as observed by Castriotta and Canella (1978) in Italian grapeseeds. Table 1 clearly shows that increasing ionic strength reduces the protein extractability, which is considerably lower in MgCl, solutions than in NaCl solutions. In addition, it seems that concentrations above 0

Grape seed proteins: a new fining agent for astringency reduction in red wine

“…Protein extraction from grape seed flour was affected strongly by the pH of the solvent. A significant positive correlation was found between the extract yield and the pH of the extraction buffer in the range from pH 9.2 to pH 10.4, thus confirming the increased grape protein solubilisation in alkaline conditions (Castriotta and Canella 1978, Fazio et al 1983, Igartuburu et al 1991. Moreover, the adjustment of the mixture pH during the extraction resulted in the reduction of the time required for extraction from 24 to 3 h. No difference in the extraction yield was found between the two buffers employed (glycine and sodium carbonate), although the composition of the final extracts was significantly different.…”

“…No significant effect was found, thus indicating that neither buffer composition nor salt concentration affected the extraction yield. These results, however, do not exclude a possible effect of the buffer and salt concentration on FE composition (Igartuburu et al 1991) and then on their effectiveness as fining agents. Based on these considerations, the following extraction conditions were established: two buffers (glycine (Gly) and sodium carbonate (Na 2CO3) ), pH 10.5 with two pH corrections and two salt concentrations (0.2M-A and 0.05M-B).…”

“…Grape seeds contain between 7.7 and 15.4% of proteins (El-Aal 1992). The extractability of grape seed proteins and their use in animal feeding has been studied (Castriotta and Canella 1978, Fazio et al 1983, Igartuburu et al 1991, El-Aal 1992, but despite reasonable in vitro digestibility, these proteins have a limited nutritional value due to their low content in essential amino acids, such as cysteine and lysine. In addition, the extraction yield was always low, reaching 16% (w/w) starting from a grape seed preparation previously treated to remove fibre (Fazio et al 1983).…”

Effect of Different Drying Methods and Storage Time on the Retention of Bioactive Compounds and Antibacterial Activity of Wine Grape Pomace (Pinot Noir and Merlot)

“…Protein content was 10.32–11.24%, comparable with previous findings of 12.2–14.39% in red grape skin and pomace. The main protein content was glutamic acid along with limited amount of lysine, tryptophan and sulfur‐containing amino acids (Igartuburu and others 1991). The lipid content of pomace was significantly ( P < 0.05) higher than skin, with the highest in PN‐P (11.09%) and the lowest in M‐S (5.02%).…”

Applications of Wine Pomace in the Food Industry: Approaches and Functions

“…Wine pomace has an amino acid profile similar to that of cereals, being rich in glutamic acid and aspartic acid and deficient in tryptophan and sulfur‐containing amino acids. Furthermore, the skin protein content is rich in alanine and lysine, a fact that is not observed in the proteins of seeds (Igartuburu and others , ). Gazzola and others () have published a complete characterization of the proteins present in grape seeds.…”