Opuntia ficus-indica by-products in ovine diets: phenolic profile and effect on milk and dairy product quality

Abstract

Polyphenols are a diverse group of secondary metabolites abundantly distributed in a wide range of plant-derived foods, including fruits, vegetables, herbs, seeds, cereals, and beverages such as coffee, tea, cocoa, and wine. These compounds have garnered considerable scientific interest due to their potential health-promoting properties, including anti-carcinogenic, antioxidant, antimicrobial, and anti-inflammatory activities. Furthermore, polyphenols have been associated with the prevention and mitigation of various chronic non-communicable diseases, such as cardiovascular diseases, type 2 diabetes, obesity, and neurodegenerative disorders. The health benefits attributed to polyphenols are closely linked to their bioavailability, which is influenced by multiple physicochemical and biological factors. An additional key determinant of bioavailability is bioaccessibility, defined as the proportion of a compound that isreleased fromthe food matrix during digestion and becomes available for absorption in the gastrointestinal lumen. Most polyphenols pass through the small intestine without being absorbed, thereby reaching the gut microbiota that colonizes the colon. This has led to the development of a bidirectional interaction between polyphenolic compounds and gut microbiota. First, polyphenols are biotransformed into their metabolites by the gut microbiota, which enhances the bioavailability of polyphenols. Second, polyphenols modulate the composition of the gut microbial community, primarily by inhibiting pathogenic bacteria and stimulating beneficial bacteria. In this context, polyphenols may act as prebiotic metabolites, promoting the growth and activity of beneficial bacteria. Furthermore, circulating polyphenols can undergo modifications in the liver through phase II enzymes, which conjugate them with methyl, glucuronide, or sulfate groups, thereby increasing their solubility [1]. The feeding system represents one of the main factors driving raw milk composition. The type of forage consumed by the sheep significantly affects the amount and type of polyphenols transferred into the milk. Polyphenol-rich forages contain bioactive compounds that can be transferred into milk during lactation [2]. The study aims to examine the chemical and nutritional characteristics of the milk and dairy products from sheep fed with feed supplemented with by-productsfrom the processing of Opuntia ficusindica. A versatile UHPLC-ESI-MS/MS can high-resolution mass spectrometry method was used to determine the (poly)phenolic profile in sheep milk and cheese samples. Additionally, the antioxidant activity and triglyceride composition of milk and cheese products will be evaluated to assess the impact of feeding Opuntia ficus-indica by-products, on their nutritional and functional properties.