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

Mohamed El Dessouky Abdel-Aziz; Mohamed Samir Darwish; Azza H Mohamed; Ayman Y El-Khateeb; Sahar E Hamed

doi:10.3390/foods9050615

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

Foods. 2020 May 11;9(5):615. doi: 10.3390/foods9050615.

Authors

Mohamed El Dessouky Abdel-Aziz¹, Mohamed Samir Darwish¹, Azza H Mohamed^{2

3}, Ayman Y El-Khateeb², Sahar E Hamed⁴

Affiliations

¹ Dairy Department, Faculty of Agriculture, Mansoura University, Mansoura, Mansoura 35511, Egypt.
² Agricultural Chemistry Department, Faculty of Agriculture, Mansoura University, Mansoura 35511, Egypt.
³ University of Florida, IFAS, Citrus Research & Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
⁴ Chemistry Department, Faculty of Agriculture, Damietta University, Damietta, 34517, Egypt.

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.

Keywords: antioxidants and antimicrobial agents; aqueous extracts; fig leaves; olive leaves; pasteurized buffalo milk.