Cider Proteins and Foam Characteristics:  A Contribution to Their Characterization

Abstract

A capillary sieving electrophoretic method for protein analysis and molecular weight determination was used to characterize ciders from Asturias, northern Spain. The total protein content (Bradford method) and the foam parameters (Bikerman method) were also analyzed to complete this characterization. The polypeptide profile, based on the molecular weight, together with exploratory and classification techniques, that is, principal component analysis (PCA) or linear discriminant analysis (LDA), allowed ciders to be differentiated on the basis of their foam assessment and the apple juice extraction technology used in the cidermaking process. In addition, the application of correlation analysis, that is, canonical correlations (CCA) or partial least-squares (PLS), revealed that the proteins with higher molecular weight were more relevant with respect to cider foamability. PLS analysis also provided a mathematical equation that is able to predict the stabilization time of foam from the polypeptide profile of the cider, because this is the foam parameter most influenced by these compounds.

Characterisation of sparkling cider by the yeast type used in taking foam on the basis of polypeptide content and foam characteristics

“…The AN-OVA was carried out with these data and no statistically significant difference exists between the means of total protein at the 95% confidence level. However, should be noted that there is a clear difference with respect to the total protein concentration of ''Natural Cider", in which our research group detected levels of protein of around 20 mg/L (Blanco-Gomis et al, 2007). The reason for the decrease in protein from one kind of cider to another could be the consumption of this substance by the yeast added for the second fermentation.…”

“…1, electrophoretic analysis detected 22 peaks that were identified as polypeptides, with molecular masses ranging between 7.2 and 102.1 kDa. The result is that there are 10 polypeptides less in the sparkling cider than in the Natural Cider and the maximum molecular mass is lower, when compared to the 154 kDa polypeptide found in the latter cider (Blanco-Gomis et al, 2007). This effect seems to be related to the decrease in protein content caused by the addition of bentonite and yeast (less important) in the second fermentation.…”

“…This work completes the first paper about proteins and foam properties in cider carried out by our research group (Blanco-Gomis, Mangas-Alonso, Junco-Corujedo, & Gutiérrez-Álvarez, 2007). In that first work the variation sources studied were the sensory evaluation and the press technology, and the cider analysed was ''Natural Cider", the other one included in the Protected Designation of Origin ''Sidra de Asturias", which is a still beverage with different foam characteristic from the ''Cider".…”

Characterization of cider by its hydrophobic protein profile and foam parameters

“…The most relevant predictor variables were polypeptides P 36 and P 7 . As Bamforth (1985) described, foam stability (related to ST parameter) is influenced by surface elasticity, tension, and viscosity, being probably the proteins with high molecular weight (Blanco Gomis et al, 2007) and more hydrophobic the most appropriated for stabilizing film of bubbles, as polypeptide P 36 . More hydrophilic proteins, such as polypeptide P 7 , can also contribute to increase bubble average lifetime (related to FS parameter) by steric hindrance and electrostatic repulsions.…”

“…Thus, in the case of ''natural" cider, low and middle molecular weight polypeptides were associated with good foaming properties, while the presence of higher molecular weight polypeptides is linked to the fast press manufacturing technology (Blanco Gomis, Mangas Alonso, Junco Corujedo, & Gutiérrez Álvarez, 2007). On the other hand, in the case of sparkling cider manufacturing, the molecular weight of polypeptides was related to yeast type used in the foam generation step (Blanco Gomis, Mangas Alonso, Junco Corujedo, & Gutiérrez Álvarez, 2009).…”