Valorization of edible films based on chitosan/hydroxyethyl cellulose/olive leaf extract and TiO2-NPs for preserving sour cream

Biodegradable edible films for sour cream packaging were developed based on chitosan (CS), hydroxyethyl cellulose (HEC), Olive leaf extract (OE), and titanium dioxide nanoparticles (TiO2-NPs). The prepared CS/HEC/TiO2-OE bionanocomposite films were evaluated for their antimicrobial and antioxidant activities as well as using FT-IR, mechanical, permeability, and contact angle. The effect of developed films on the lipid oxidation, microbiological load, and chemical properties of sour cream was investigated. The fabricated films had an antimicrobial impact against all tested strains. The film containing 8 % OE showed effective protection against fat oxidation, with a peroxide value of 3.21 meq O2/kg, a para-anisidine value 5.40, and free fatty acids of 0.82 mg KOH/kg. The films with OE 4 % and 8 % have a good effect on the microbiological load of sour cream for 90 days. These films did not influence the chemical composition of sour cream and therefore can be used in this sort of dairy product.

Characterization of a fermented dairy, sour cream: Lipolysis and the release profile of flavor compounds

Lipolysis and flavor development during fermentation of sour cream were studied by evaluating the physicochemical changes, sensory differences and volatile components. The fermentation caused significant changes in pH, viable count and sensory evaluation. The peroxide value (POV) decreased after reaching the maximum value of 1.07 meq/kg at 15 h, while thiobarbituric acid reactive substances (TBARS) increased continuously with the accumulation of secondary oxidation products. The Free fatty acids (FFAs) in sour cream were mainly myristic, palmitic and stearic. GC-IMS was used to identify the flavor properties. A total of 31 volatile compounds were identified, among which the contents of characteristic aromatic substances such as ethyl acetate, 1-octen-3-one and hexanoic acid were increased. The results suggest that lipid changes and flavor formation in sour cream are influenced by fermentation time. Furthermore, flavor compounds may be related to lipolysis such as 1-octen-3-one and 2- heptanol were also observed.

Effect of probiotic bacteria on physicochemical, microbiological, textural, sensory properties and fatty acid profile of sour cream

Sour cream is a dairy product with good potential to act as a food carrier for probiotic bacteria. The effect of probiotic cultures on the quality of sour cream from dry dairy ingredients was assessed during 5 weeks of storage. The treatments design was as follows: Bifidobacterium, Bifidobacterium + Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus acidophilus + Lactobacillus casei and Lactobacillus casei. Fatty acids profile, texture, microbial load and sensory characteristics were analyzed. Comparison of fatty acids of different creams produced showed that there is a significant difference between the produced creams. There are a wide range of fatty acids in the structure of sour cream fat. Also, with the addition of these bacteria, the texture of the samples became firmer during storage. The sensory analyses showed that the addition of all three bacteria increased the overall acceptance of this product by the panelists. It is suggested that sour cream fortified with probiotics well orientated functional food had accepted composition and sensory properties.