Effect of olive leaves feeding on phenolic composition and lipolytic volatile profile in goat milk

Abstract

The aim of this study was to evaluate phenolic composition, antioxidant potential, and lipolytic events in raw milk obtained from goat fed a dietary supplementation with olive leaves (OL), a by-product of the olive oil production chain. For this purpose, 30 Saanen goats were randomly allocated into 2 groups of 15 goats each: the control group received a standard diet that was prepared by taking into account the nutritional needs of lactating goats, whereas the experimental group (EG) was fed with an OL-supplemented diet (10% on a dry matter basis). At the end of the 30 d of the trial, the individual milk samples were collected and immediately analyzed for total phenolic content and antioxidant activity (AOA). Subsequently, the individual phenolic compounds have been identified and quantified through an ultra-high-performance liquid chromatography system and a characterization of free fatty acids released in milk has been performed. The results showed a positive effect of dietary OL supplementation in improving total phenolic content and AOA; furthermore, 19 phenolic compounds, including phenolic acids, flavonoids, simple phenols, and secoiridoids, have been identified in EG milk. In addition to this, a reduced accumulation of free fatty acids has been found in EG milk, and this finding leads us to hypothesize an inhibitory action of the identified phenolic compounds toward the enzymes responsible for lipolytic events. The use of the molecular docking approach verified the interactions, defining a fairly interesting framework for cinnamic acid, which should be able to noncovalently bind these enzymes, interfering with the recruitment of the substrate and therefore, slowing down their hydrolytic activity. In any case, this information will be subjected to in vitro evaluations for an accurate characterization of the biochemical mechanisms that can be established in milk naturally enriched with bioactive compounds.

Supplementation with antioxidants and phenolic compounds in ruminant feeding and its effect on dairy products: a systematic review

“…Animal models included were sheep (2 papers), cows (9 papers) and goats (4 papers). Some studies also reported the progeny of the animals such as primiparous (Safari et al ., 2018; Li et al ., 2021) and multiparous (Hausmann et al ., 2018; Safari et al ., 2018; Li et al ., 2021; Wang et al ., 2021) and included the period of lactation (Ianni et al ., 2019, 2021; Bonanno et al ., 2019b; Mapato et al ., 2021; Menci et al ., 2021) or specified mid-lactation (Scuderi et al ., 2019; Simitzis et al ., 2019). Design of the studies included randomized (Cais-Sokolińska et al ., 2015; Hausmann et al ., 2018; Safari et al ., 2018; Ianni et al ., 2019; Bonanno et al ., 2019a; Walkenhorst et al ., 2020; Li et al ., 2021; Wang et al ., 2021), stratified (Scuderi et al ., 2019; Walkenhorst et al ., 2020), allocated (Delgadillo-Puga et al ., 2019; Simitzis et al ., 2019) and 4 × 4 Latin square design with a 2 × 2 factorial arrangement (Mapato et al ., 2021).…”

“…Interventions with plants, herbs, seeds, grains and isolated bioactive compounds were used in the studies. Among the plants included in the interventions were Acacia farnesiana (Delgadillo-Puga et al ., 2019), bamboo grass (Mapato et al ., 2021), olive leaves (Ianni et al ., 2021), herbal feed additives (Walkenhorst et al ., 2020) and Perilla frutescens leaf (Wang et al ., 2021). Other studies included seeds such as false flax cake (Cais-Sokolińska et al ., 2015) and pomegranate seeds (Safari et al ., 2018).…”

“…One of the most important aspects of interventions with bioactive compounds in the feeding of dairy animals is that these compounds need to be bioavailable in the products obtained. Among the studies included, five reported the presence of bioactive compounds in milk (Delgadillo-Puga et al ., 2019; Ianni et al ., 2019, 2021; Bonanno et al ., 2019a, 2019b) and three in the composition of cheese (Ianni et al ., 2019; Bonanno et al ., 2019a, 2019b). The inclusion of Acacia farnesiana at 20 and 30% in the diet of goats significantly increased the total phenolic content in the milk and bioactive compounds such as gallic, chlorogenic, ferulic acids and catechin were only detected in milk from supplemented goats (Delgadillo-Puga et al ., 2019).…”

“…Olive leaf supplementation is another intervention that significantly increases the concentration of phenolic compounds in milk. The main compounds detected in this milk were cinnamic acid, chlorogenic acid and tyrosol (Ianni et al ., 2021). An interesting finding in the profile of bioactive compounds in milk was the content of chlorogenic acids (CGAs), since these are among the most common bioactive compounds in plant foods such as coffee, apples, tea and berries, as well as in beverages such as wine (Zanotti et al ., 2015).…”

Nutritional Properties of Milk from Dairy Ewes Fed with a Diet Containing Grape Pomace

“…Fifteen mL of each milk sample were cool centrifugated at 4000× g rpm for 15 min. The fat was removed, the supernatant was recovered, filtered and quantified using Bradford method [24] and Bovine Serum Albumine (BSA) as standard. Protein samples (7.5 µg) were diluted in sample buffer (0.5 M Tris-HCl, pH 6.8; 2% (w/v) SDS; 7% (v/v) glycerol; 4.3% (v/v) β-mercaptoethanol; 0.0025% (w/v) bromophenol blue), boiled for 5 min and loaded into a 12% polyacrylamide gel.…”