Proteolysis of Livanjski cheese during ripening

Abstract

Livanjski cheese belongs to the group of hard cheeses which is traditionally produced in Livno (Bosnia and Herzegovina). Proteolytic changes during the ripening of Livanjski cheese have not been investigated extensively. The aim of this paper was to determine its proteolytic changes during the different stages of ripening. Five Livanjski cheeses (from raw cow's or a mixture of sheep's and cow's milk) were observed during the ripening to evaluate its typical proteolytic profile. An electophoretic profile of Livanjski cheese was determined by Urea-polyacrylamide gel electrophoresis (urea-PAGE) and a densitometric evaluation of the urea-PAGE gels was performed using a densitometer. The water-soluble nitrogen fraction in the total nitrogen (WSN %TN) and the 12%-TCA-soluble nitrogen fraction in the total nitrogen (TCA-SN %TN) of the cheese were determined using the Kjeldahl method. Degradation of α s1 -casein by chymosin caused a significant decrease (P < 0.05) of relative content of this protein in Livanjski cheese at the sixth week point of ripening. Due to the activity of chymosin on αs1-casein, αs1-I-casein and αs1-II-casein developed, which caused a significant increase (P < 0.05) of Index alpha. The relative ratio of β-casein significantly decreased (P < 0.05) during ripening leading to a significant accumulation (P < 0.05) of degraded product (sum γ 1 -casein, γ 2 -casein and γ 3 -casein). These proteolytic changes caused a significant increase (P < 0.05) of Index betta. Accumulation of medium, small peptides and amino acids caused a significant (P < 0.05) increase of the relative content of WSN %TN and TCA-SN %TN. In general, proteolysis of Livanjski cheese during ripening was moderate probably due to the low moisture content and low water activity, although it was produced from raw milk. Taking into account that the ratio β-casein : α s1 -casein at the end of ripening was 1.46, it could be concluded that degradation of α s1 -casein could be the indicator of the maturity of Livanjski cheese. Due to that Livanjski cheese could be classified as "α-type of ripening" cheese.

Protein, fatty acid, mineral profiles and antioxidant potential of Kupres cheese at different stage of ripening

“…This was supported by the SDS-profiles of WSN fraction and Tris-HCl extract of one-day-old cheese which contained numerous high molecular weight products (Figure 1, Lines 2 and 1). Similar values of WSN/TN and TCA-SN/TN were observed by Kalit et al (2016) at the beginning of the ripening of traditional cheese from Livno. During the first month of ripening, relatively slow proteolytic changes were induced; after 30 days of ripening WSN/TN content increased up to 10.15 % mainly due to the degradation of previously formed proteolytic products and the increase of TCN-SN/TN up to 3.59 % (Table 1).…”

Microbial diversity of Livanjski cheese with the emphasis on lactic acid bacteria based on culture‐dependent and sequencing method

“…The microbial diversity of traditional Livanjski cheese has not yet been described properly. The current information is primarily focused on cheese quality and physicochemical parameters (Hrković et al ; Matić ; Kalit et al ). This study was aimed at determining microbial and fungal diversity in random samples of Livanjski cheese with a focus on the identification and acquisition of LAB strains.…”

“…Regarding specific farmhouse conditions, good hygiene practices and food safety control are very limited or nonexistent. Despite the facts mentioned above, the Livanjski cheese from raw milk is of high demand because of its intense flavour and specific sensory properties (Hrković et al ; Matić ; Kalit et al ). The authenticity and quality of artisanal cheeses resulted from the combination of factors such as milk quality, good hygienic practice and traditional technology in conjunction with the microbial community, which have an essential effect on cheese quality (Bonomo and Salzano ; Fraga‐Cotello et al ; Bokulich and Mills ; Montel et al ).…”

Cross‐linking duration impacts on Hatay cheeses with microbial transglutaminase enzyme

“…The α s1 -casein ratios of cheese samples generally decreased during storage. Many researchers have reported that the α s1 -casein ratio decreases during maturation (Tang et al 2005;Kalit et al 2016). Tang et al (2005) reported that the addition of mTG enzyme accelerated the polymerisation of all casein fractions, only that most of the β-casein was preserved at the end of the cross-linking period, as it was more resistant to hydrolysis.…”