Tools to develop dairy ingredients: bioactive and preservative purposes
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High cholesterol levels are a major concern these days due to the serious illnesses associated with this problem. Interesting progress has been made to overcome this situation and decrease the absorption of cholesterol by the body, including the incorporation of phytosterols in foods that can compete with cholesterol and decrease its absorption due to the structural similarity between the cholesterol and phytosterols. Mycosterols have been studied for the same purpose, particularly Ergosterol, which has already been shown to be more effective in reducing the absorption of cholesterol than phytosterols. Thus, the present proposal intended to explore mushroom´s bio-waste as a source of mycosterols, turning this bio-waste in an economic valuable raw material through the extraction of added value molecules. For this purpose, mycosterols were extracted from Agaricus bisporus L. by ultrasound-assisted extraction (UAE) in previously optimized conditions, characterized in terms of mycosterols (ergosterol) by HPLC-UV, and further evaluated for their hypocholesterolemic potential in CaCo2 cells. Furthermore, the enriched mycosterol extracts and the free ergosterol were incorporated in cottage cheese, in the free form and their stability and effects on the cheese characteristics were evaluated over the shelf life of the product. From the obtained results, it can be stated that the incorporation of A. bisporus extract and pure ergosterol did not cause significant differences in the cottage cheese. Regarding the physicochemical parameters, the color of cheese incorporated with the extract was the brownest compared to the other two samples (cottage cheese with ergosterol and control cottage cheese). Concerning the fatty acids, a dominance of palmitic acid followed by oleic and capric acids was detected. Saturated fatty acids were predominant in the samples followed by mono and polyunsaturated ones. Likewise, two types of sugars have been detected, lactose and glucose. The latter has been observed only in cheese incorporated with A. bisporus. In terms of microbial growth, the incorporations did not cause any significant alterations to the normal microorganisms found in the cottage cheese. From the hypocholesterolemic evaluation, it was possible to determine that Caco2 cells absorbed 43.89% of the cholesterol from the control cheese. On the other hand, cheese with pure ergosterol reduced cholesterol absorption by approximately 21.1%, while cheese with A. bisporus reduced absorption by approximately 30.24%. These results highlight the capacity of ergosterol to reduce the absorption of cholesterol, being an interesting candidate for the development of functional foods for hypocholesterolemic effects. Keywords: Cottage cheese, functional foods, mycosterols, hypocholesterolemic agents.
Phytosterols can be ingested and consequently absorbed by the human body, leading to a direct absorption competition with cholesterol, thus reducing its absorption [1]. Mushrooms are described as having several bioactive components, such as mycosterols (ergosterol), which, similarly to phytosterols, exhibit a strong hypocholesterolemic potential [2]. Thus, the objective of this work was to obtain mycosterol enriched extracts from A. bisporus L. bio-waste for further incorporation in sheep cottage cheese, in order to develop a functional food with hypocholesterolemic effects. Sheep cottage cheeses with pure ergosterol, and a control cheese with no incorporation were prepared. The extracts were obtained by ultrasound assisted extraction (UAE) and the identification and quantification of their compounds was achieved through HPLC-UV. The toxicity and hypocholesterolemic activity were sought through a CaCo2 cell line. In terms of analysis, the nutritional value was analyzed according to AOAC procedures, the physical parameters included texture, external colour and water activity, and the microbial load (total aerobic mesophiles, enterobacteria, Psychrotrophic bacteria, yeasts, molds and Staphylococcus aureus) was also analyzed along a shelf life of 9 days according to the International Organization for Standardization (ISO) 6887-1:2003 [3,4].
No significant differences were verified for the nutritional parameters. The color of the cheeses incorporated with the extract hinted towards a browner tone when compared to the other two samples (cottage cheese with ergosterol and control cottage cheese). A dominance of palmitic acid followed by oleic and capric acids was detected, being the saturated fatty acids the predominant ones. Lactose and glucose were the two detected soluble sugars; being glucose only observed in cheese incorporated with A. bisporus, probably present in the extract. Also, the incorporations did not cause any significant alterations to normal microbial growth. Despite an increase of enterobacteria in the cheeses with the incorporation of the two agents, this increase was also verified for the control cottage cheese.
CaCo2 cells absorbed 43.89% of cholesterol from the control cheese, while the cheese with pure ergosterol reduced cholesterol absorption by approximately 21.1%, and cheese with A. bisporus by approximately 30.24%. These results highlight the capacity of ergosterol to reduce the absorption of cholesterol, being an interesting candidate for the development of functional foods.
