Rheological properties of Colombian‐Caribbean‐coast sour cream from goat milk

Development of sour cream with vegetable oils using a food emulsion stabilised by an emulsifying complex

This scientific work describes the research that aims to study the use of a finely dispersed, aggregately stable food emulsion with a mass fraction of blended oil of 50% and xanthan gum in the composition of sour cream with vegetable oils as an analogue of traditional sour cream. The samples of fat-containing fermented-milk bases as a component of sour cream with vegetable oils with a fat content of 10-20% were obtained using two methods. The first method consists in normalising the fat content of the fermented-milk base obtained by fermentation of skimmed cow's milk with a food emulsion, and the second one – is in the fermentation of a normalised mixture consisting of a food emulsion and skimmed cow's milk. When comparing the duration of fermentation of skimmed cow's milk and normalised mixtures with a fat content of 10 to 20%, it was established that in order to achieve the minimum value of the titrated acidity of the clot of 60 °T, the duration of fermentation of skimmed cow's milk is 6 hours, of a normalised mixture with a fat content of 10% – 8 hours, 15% – 12 hours, 20% – 16 hours. According to the organoleptic quality indicators, the samples of fat-containing fermented-milk bases with a fat content of 20%, obtained by two methods, had an indiscrete but unsuitable thick consistency, which was adjusted using xanthan gum. According to the organoleptic quality indicators, it was established that in order to obtain a sour cream with vegetable oils with an indiscrete and thick consistency, 0.15% of xanthan gum should be added to the fat-containing base obtained by the first method, and 0.20% – to the fat-containing base obtained by the second method. The study of determining the content of polyunsaturated fatty acids in sour cream with vegetable oils with a fat content of 20% shows an increased content of omega-3 and omega-6 fatty acids – 2.13% and 10.88%, respectively, compared to sour cream obtained by the traditional technology.

Effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese from goat milk

Textural attributes are a manifestation of the rheological properties and physical structure of foods, cheeses among these. In order to describe these physical properties, the objective of this work was to analyse the effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese made from goat milk with 3.75% (F1), 4.00% (F2) and 4.25% (F3) fat content, through prediction made by a four-term Prony series based on Chen's model. For this, stress relaxation data and stress relaxation spectra were analysed. Moreover, textural attributes by texture profile analysis were measured. Physicochemical results were similar to those published by other authors, and all samples meet national and international standards. Results from this work showed that Chen's model could be successfully used to describe the effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese made from goat milk. F1 had the highest elastic response, with the most significant residual modules ( P₀) and relaxation times (τ₁, τ₂ and τ₃). On the other hand, residual modules and relaxation times (τ₁, τ₂ and τ₃) for cheeses F2 and F3 did not present statistically significant differences (p > 0.05). Besides, by interpretation of the stress relaxation spectra, F1 presented the firmest structure (greatest distribution function and relaxation time) which was characterised by the highest elastic behaviour. Finally, according to texture profile analysis test, F1 had the highest hardness, cohesiveness and chewiness, whereas F2 and F3 did not present statistically significant differences (p > 0.05) between them.