Variations in milk protein fractions affect the efficiency of the cheese-making process

Abstract

The aim of this study was to assess the influence of the amounts of the α-, α-, β-, and κ-casein (CN) and the α-lactalbumin and β-lactoglobulin protein fractions on the efficiency of the cheese-making process independently of their genetic polymorphisms. The study was carried out on milk samples from 1,271 Brown Swiss cows from 85 herds classified into 4 categories according to management, feeding, and housing characteristics (traditional and modern systems). To assess the efficiency of the cheese-making process, we processed the milk samples according to a laboratory cheese-making procedure (1,500 mL/sample) and obtained the following measures: (1) 3 percentage cheese yields (%CY, %CY, %CY), (2) 2 daily cheese yields obtained by multiplying %CY (curd and total solids) by daily milk yields (dCY, dCY), (3) 4 measures of nutrient recovery in the curd (REC, REC, REC, REC), and (4) 2 measures of cheese-making efficiency in terms of the ratio between the observed and theoretical %CY (Ef-%CY, Ef-%CY). All the aforementioned traits were analyzed by fitting 2 linear mixed models with protein fractions as fixed effects expressed as percentage in the milk (model M-%milk) and as percentage of the total casein content (model M-%cas) together with the effects of total casein content (only in model M-%cas), daily milk yield (only in model M-%milk; not for dCY traits), dairy system, herd (random effect), days in milk, parity, and vat. The efficiency of overall cheese yield (Ef-%CY) was mostly positively associated with β-CN content in the milk, whereas Ef-%CY was greater with higher amounts of κ-CN and α-CN (M-%milk) due to the strong influence of both fractions on the recovery rate of milk components in the curd (fat and total solids, protein with α-CN only) when expressed as percentage of milk and of total casein; only β-CN was more important for REC. In contrast, we found β-lactoglobulin to be highly negatively related to all the traits related to the cheese-making process and to the daily cheese yield per cow, whereas α-lactalbumin was positively associated with the latter traits. Additional research on this topic is needed, with particular focus on the genetic and genomic aspects of the role of protein fractions in the cheese-making process and on the associations between genetic polymorphisms in milk protein and milk nutrient recovery in the curd.

Variation of Detailed Protein Composition of Cow Milk Predicted from a Large Database of Mid-Infrared Spectra

“…Cipolat-Gotet et al (2018) [27] determined detailed milk protein composition of 1264 Italian BS samples through reversed phase HPLC and results showed that protein fraction contents were similar to those reported in the current study, except for κ-CN, which will be discussed more in details later on, and β-LG. Differences in the latter were probably determined by the wider lactation range in the study of Cipolat-Gotet et al (2018) [27] compared with the present work.…”

Genomic Analysis of Milk Protein Fractions in Brown Swiss Cattle

“…Among the whey protein fractions, we found β-LG in amounts approximately 3.5 times that of α-LA. This result is in agreement with data from previous studies [9,19,20].…”

“…Milk protein composition is affected mainly by genetic factors, as well as by non-genetic factors. In this study, the caseins αS1-CN and β-CN were found in higher proportions than αS2-CN and k-CN, representing approximately 75.61% of the total casein content, in agreement with various studies on different dairy breeds [5,10,18,19]. Among the whey protein fractions, we found β-LG in amounts approximately 3.5 times that of α-LA.…”

Milk protein fractions strongly affect the patterns of coagulation, curd firming, and syneresis

“…Traditional single-point MCP and CF t model parameters were analyzed with 2 linear mixed models using the same approach taken by Cipolat-Gotet et al (2018). The first model (referred to as M-g/L) included daily milk yield (dMY, kg/d) and defined the quantitative effect of each protein fraction; the protein fractions were expressed as grams per liter of milk.…”