title: Proteolysis on Reggianito Argentino cheeses manufactured with natural whey cultures and selected strains of Lactobacillus helveticus.
abstract: Reggianito Argentino cheese is traditionally manufactured with whey starter cultures that provide typical and intense flavor but can cause poor quality standardization. In this study, the influence of natural and selected starters on Reggianito Argentino cheese proteolysis was investigated. Cheeses were manufactured with three strains of Lactobacillus helveticus (SF133, SF138 and SF209) cultured individually in sterile whey and used as single or mixed starters. Control cheeses were made with natural whey starter culture. Cheeses were analyzed to determine gross composition, as well as total thermophilic lactic flora. Proteolysis was assessed by N fractions, electrophoresis and liquid chromatography. Gross composition of the cheeses did not significantly differ, while viable starter cell counts were lower for cheeses made with strain SF209 alone or combined with other strains. Soluble N at pH 4.6 was the same for cheeses made with natural or selected starters, but soluble N in 12% trichloroacetic acid and 2.5% phosphotungstic acid was significantly higher in cheeses made with starters containing strain SF209. Nitrogen fractions results indicated that natural whey starter cultures could be replaced by several starters composed of the selected strains without significant changes to proteolysis patterns. Starter cultures prepared only with SF209 or with the three selected L. helveticus strains produced cheese products with significantly more proteolysis than control cheeses. Chromatographic profiles analyzed by principal components showed that three main peaks on chromatograms, presumptively identified as Tyr, Phe, and Trp, explained most of variability. Principal component scores indicated that cheese samples were grouped by ripening time, which was confirmed by linear discriminant analysis. On the contrary, samples did not cluster by Lactobacillus strain or type of starter.
authors.affiliation: Programa de Lactología Industrial, Facultad de Ingeniería Química (Universidad Nacional del Litoral), Santiago del Estero 2829-S3000AOM Santa Fe, Argentina. ehynes@fiqus.unl.edu.ar
authors.forename: E R
authors.initials: ER
authors.lastname: Hynes
authors.forename: C V
authors.initials: CV
authors.lastname: Bergamini
authors.forename: V B
authors.initials: VB
authors.lastname: Suárez
authors.forename: C A
authors.initials: CA
authors.lastname: Zalazar
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001118:Argentina; D002611:Cheese / Q000032:analysis / Q000382:microbiology*; D002851:Chromatography, High Pressure Liquid; D005524:Food Technology; D007778:Lactobacillus / Q000378:metabolism*; D008894:Milk Proteins; D010447:Peptide Hydrolases / Q000378:metabolism*; D010649:Phenylalanine / Q000032:analysis; D013997:Time Factors; D014364:Tryptophan / Q000032:analysis; D014443:Tyrosine / Q000032:analysis; D000067816:Whey Proteins
chemical_list: D000596:Amino Acids; D008894:Milk Proteins; D000067816:Whey Proteins; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan; D010447:Peptide Hydrolases