Bioaccessibility and antioxidant activity of PCL‐microencapsulated olive leaves polyphenols and its application in yogurt

Abstract

Polycaprolactone (PCL)was used via double emulsion/solvent evaporation technique for the encapsulation of polyphenols olive leaves (OLs) extracts. In this study, the PCL‐microcapsules loaded with OLs polyphenols extract powder were characterized by scanning electron microscopy and fourier transform infrared spectrometry analysis. Their total phenolic (TPC), total flavonoid (TFC) contents, and antioxidant activities (DPPH, FRAP, and ABTS), and polyphenols stability were measured after oral, gastric, and intestinal steps of in vitro digestion. PCL‐microcapsules were utilized in formulating novel functional yogurt containing 0, 25, 50, and 75 mg of TPC estimated as mg GAE (added as PCL‐microcapsules) per 100g yogurt. All yogurt samples were evaluated for their pH, acidity, syneresis, viscosity, and color during storage. In vitro digestion significantly affected the phenolic composition in non‐encapsulated extract whereas it had a lower impact on encapsulated phenolics. Higher protection was provided for encapsulated OLs extract and their higher release was observed at the intestinal phase. Unlike the undigested OLs extract, which had a TPC of 490 mg GAE/100 g, lower values of TPC (136 and 289 mg GAE/100 g) were obtained for non‐encapsulated and encapsulated OLs extract, respectively, in the intestinal fluids. Yogurt with PCL‐microcapsules had lower viscosity, syneresis, and color parameters, compared to control yogurt. Thus, OLs represent a valuable and cheap source of polyphenols that can be successfully applied in microencapsulated form, in formulating functional yogurt.

The Potential of Olive Leaf Extract as a Functional Ingredient in Yoghurt Production: The Effects on Fermentation, Rheology, Sensory, and Antioxidant Properties of Cow Milk Yoghurt

“…The highest decrease in viscosity was observed on the 14th day of storage ( Figure 2 ), which also corresponded to the observed decrease in pH values ( Figure 1 ) detected during the first 14 days. Such trends were also reported by Cho et al [ 8 ] and El-Messery et al [ 11 ], who also detected a decrease in viscosity of all samples during 14 days of cold storage. After that period, viscosity started to increase, reaching at the end almost identical values as on the first day for some samples (control, OLE 1.5%, and OLE 3%) ( Figure 2 ).…”

“…Some authors have already studied the possibilities of adding OLE to yoghurt, in order to examine the options of supplementation (liquid, concentrated, powdered, encapsulated, pure oleuropein), as well as to increase its shelf life and/or functionality [ 6 , 8 , 9 , 10 ]. In these studies, the used extracts were usually obtained by boiling in hot water [ 6 , 10 ] or extracted from organic solvents such as ethanol, subsequently subjecting them to further processing operations such as freeze-drying, evaporation, or encapsulation [ 8 , 10 , 11 ], to obtain a higher concentration of active compounds to be added into yoghurt. From the perspective of developing new products, employment of so many intermediate steps might not simply appear unpractical but also expensive for large-scale applications.…”

Encapsulation of bioactive compounds extracted from date palm seeds (Phoenix dactylifera L.) and their use in functional food

“…According to the method of El-Messery et al ( 23 ), the syneresis rate of yogurt was calculated using the following Equation (3):…”

Stability and Bioaccessibility of Lignans in Food Products

“…The lower amounts released during all stages of digestion indicated that these compounds were held within the capsules and were not exposed to the digestion fluids. This is due to the low solubility of the encapsulation material at low pH, which prevents the phenols release in the acidic environment . Thus, the encapsulated samples in this system were less bioaccessible and would most likely pass through the colon without being absorbed in the upper gastric tract.…”