Addition of Olive Leaf Extract (OLE) for Producing Fortified Fresh Pasteurized Milk with an Extended Shelf Life

Abstract

An olive leaf extract (OLE) has been tested in vitro for its antibacterial activity and ability to inhibit α-glucosidase enzyme. OLE was also evaluated for its potential, when added to pasteurized milk, to preserve nutritional parameters and to limit microbial growth, thus prolonging shelf life. In vitro assays demonstrated a strong antibacterial efficacy of OLE mainly against Bacillus cereus and the capacity to inhibit α-glucosidase enzyme (IC50) when used at 0.2 mg oleuropein/mL. The milk fortification with OLE at 3.6 mg of oleuropein/mL of milk reduced total mesophilic bacteria at undetectable level after 6 d (expiration date) and by 1 log CFU/mL after 10 d. Moreover, OLE addition at 1.44 and 3.6 mg of oleuropein/mL of milk significantly reduced fat and lactose losses up to 10 d. The results motivate the use of the OLE to make a new functional milk with an extended shelf life.

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

“…The HPLC results for the phenolic compounds of FLE were similar to the results reported by Nadeem and Zeb [68], who stated that caftaric acid, quercetin-3, 7-diglucoside, and quercetin-3-glucoside were the main phenolic compounds. The levels of phenolic compounds in OLE in the present study are consistent with those of Palmeri et al [9], who showed that all phenolic compounds in OLE classified as polyphenols. As widely presented in the literature; oleuropein was 90% of phenolic compounds, followed by ligstroside (1.12 mg/g dried extract) and luteolin 7-O-glucoside (0.81 mg/g dried extract).…”

“…On the other hand, this procedure causes a significant loss of the flavor, color, several vitamins, and antimicrobial compounds [6][7][8]. However, pasteurized milk is a high-nutritional-value product, but with a limited shelf life (only 5-7 days) at 5-8 • C, and it is costly compared with UHT milk [9]. The pasteurization techniques of milk are divided into two common types, according to the Codex Alimentarius [10].…”

Physical and Sensory Properties of Mayonnaise Enriched with Encapsulated Olive Leaf Phenolic Extracts

“…Recently, several studies have proposed the enrichment of different food products with an olive leaf phenolic extract (OLE), as in the case of vegetable oils, due to their antioxidant activity (i.e., sunflower, soybean, maize, and frying oils) [2], or meat products against oxidative [3] and microbial spoilage [4]. Moreover, the use of OLE was also tested in cereal [5] and dairy products [6]. Apart from having healthy, antioxidant, and antimicrobial properties, olive polyphenols have been proven to exert important technological functionality, such as a water/oil holding capacity and emulsifying activity [7], and can represent a useful multifunctional ingredient that can help in the production and stabilization of complex food products such as emulsions.…”

Evolution of VOC and Sensory Characteristics of Stracciatella Cheese as Affected by Different Preservatives

“…Its contribution on shelf life and chemical and sensory characteristics of stracciatella is still unknown. OLE has been recently tested for antimicrobial activity based on the high polyphenols content [ 32 , 33 , 34 ].…”