Potential Activity of Aqueous Fig Leaves Extract, Olive Leaves Extract and Their Mixture as Natural Preservatives to Extend the Shelf Life of Pasteurized Buffalo Milk

Abstract

The aim of this study was to evaluate fig (Ficus carica L.) leaves’ extract (FLE), olive (Olea europaea L.) leaves’ extract (OLE), and their mixture (MLE), to extend the shelf life of pasteurized milk. OLE, FLE, and their mixture MLE (1:1) were added to the pasteurized milk in different concentrations (0.2%, 0.4%, and 0.6%). Several tests were then conducted to determine the activity of these extracts. The antioxidant activity as IC50 was determined by using DPPH radical assay. FLE showed higher IC50 (30.21 µg/mL) compared to the IC50 of OLE (22.43 µg/mL). Phenolic compounds were identified by using high-performance liquid chromatography (HPLC). The highest antimicrobial activity was obtained with 0.6% concentration. Organoleptic properties indicated that the addition of these extracts did not affect the sensory properties of pasteurized milk. Pasteurized milk treated with 0.6% of FLE, OLE, and MLE has significantly decreased (p ≤ 0.05) lipase and protease activity during the storage period, at 5 °C. The results indicated that extending the shelf life of pasteurized milk from 5 to 16 days was successfully achieved through using 0.6% of FLE, OLE, and MLE. The combination of the two extracts (MLE) provides an efficient and safe method to prolong the shelf life of pasteurized milk, without altering the properties of pasteurized buffalo milk.

Effect of Removing the Bitter Taste of Olive Leaves on Its Antioxidant and Antibacterial Properties in Some Food Products

“…Some phenolic compounds were not detected, such as benzoic acid, in T3, vanillic acid in T3, T4 and T6, caffeic acid in T7 and Naringeninin T6. These results are mostly consistent with many other studies (Rimawi & Salim 2016;Ghomari et al, 2019 andAbdel-Aziz et al, 2020), especially about agreement that Oleuropein is the greatest ingredient in olive leaves. Oleuropein, as previously mentioned, is responsible for the bitter taste in olive leaves and decreased in all treated samples in proportions ranging from 87.89 to 98.28 %.…”

Sustainable Food Systems: The Case of Functional Compounds towards the Development of Clean Label Food Products

“…Cheese manufactured with kiwi extracts was rich is polyphenols and phytosterols, while kiwi protein could replace soy protein. Extracts obtained from figs and olive leaves were tested individually and combined as milk preservatives, increasing its shelf life to 11 days [ 165 ]. Tsouko et al [ 166 ] incorporated phenolic-rich extracts from palm oil by-products in sunflower oil.…”

Biosynthesis of Silver Nanoparticles by Polysaccharide of Leucaena leucocephala Seeds and Their Anticancer, Antifungal Properties and as Preservative of Composite Milk Sample

“…Proteolytic Activity. The proteolytic activity of milk samples was determined according to El Dessouky Abdel-Aziz et al [25] with slight modification. Briefly, approximately 0.5 mL buffer (4.5 mM KH 2 PO 4 ; pH 7.5) was transferred into a screw-capped test tube and was mixed with 24 mg of Azocoll, followed by incubation for 5 min at 36 °C.…”

“…Lipolytic Activity of Composite Milk Sample. The lipolytic activity of the tested milk samples was determined by estimating the time required to liberate estimable free fatty acids (FFA) according to El Dessouky Abdel-Aziz et al [25], with slight modification. Briefly, a volume of composite milk sample (5 mL) mixed with 25 mL ethanol was mixed with 10 mL, and then 3 drops of 1% phenolphthalein indicator solution were added.…”