Milk kefir is gaining popularity due to its high probiotic content. This study focuses on fortifying milk kefir with date syrup to enhance its sensory attributes, with the goal of encouraging consumption among the younger generation. Date syrup was added to milk kefir in specific proportions (2, 4, 6, 8, and 10% per 100 mL of milk). The selection of the most suitable percentage (10%, 74 °Bx) was determined based on sensory preferences indicated by the panellists. The newly developed fermented beverage underwent physicochemical and biochemical analyses over a 14-day fermentation period. Results revealed that the addition of date syrup led to a significant (P ≤ 0.001) decrease in pH and total soluble solids (TSS) content, accompanied by a noteworthy increase in total phenolic, flavonoids, condensed tannins contents and antioxidant activity (almost 2-fold). Liquid chromatography - heated electrospray ionisation - mass spectrometry (LC-HESI-MS/MS) results identified the presence of a newly formed and important antifungal compound, p-hydroxyphenyllactic acid (HPLA), showing a progressive increase in quantity during the fermentation process (13.8-fold on the 14th day of fermentation). Hence, the outcomes of this study offer compelling evidence that a novel category of functional beverage can be developed by employing milk kefir as an appropriate starter with the incorporation of date syrup.
Abbès, F., Kchaou, W., Blecker, C., Ongena, M., Lognay, G., Attia, H., and Besbes, S. (2013). Effect of processing conditions on phenolic compounds and antioxidant properties of date syrup. Industrial Crops and Products, 44: 634–642.
Al Hilfi, M.K., Al-Fekaiki, D.F., and Al-Hilphy, A.R. (2019). Identification and determination of metal elements of dates syrup extracted from various varieties using SEM-EDS technique. Basrah Journal of Agricultural Sciences, 32(2): 126–134.
Belkhir, M., Rebai, O., Dhaouadi, K., Congiu, F., Tuberoso, C.I.G., Amri, M., and Fattouch, S. (2013). Comparative analysis of Tunisian wild Crataegus azarolus (yellow azarole) and Crataegus monogyna (red azarole) leaf, fruit, and traditionally derived syrup: phenolic profiles and antioxidant and antimicrobial activities of the aqueous-acetone extracts. Journal of Agricultural and Food Chemistry, 61(40): 9594–9601.
Brunschwig, C., Leba, L.J., Saout, M., Martial, K., Bereau, D., and Robinson, J.C. (2016). Chemical composition and antioxidant activity of Euterpe oleracea roots and leaflets. International Journal of Molecular Sciences, 18(1): 61.
Carmona, L., Sulli, M., Diretto, G., Alquézar, B., Alves, M., and Peña, L. (2022). Improvement of antioxidant properties in fruit from two blood and blond orange cultivars by postharvest storage at low temperature. Antioxidants, 11(3): 547.
Carullo, G., Spizzirri, U.G., Montopoli, M., Cocetta, V., Armentano, B., Tinazzi, M., Sciubba, F., Giorgi, G., Di Cocco, M.E., Bohn, T., Aiello, F., and Restuccia, D. (2022). Milk kefir enriched with inulin‐grafted seed extract from white wine pomace: chemical characterisation, antioxidant profile and in vitro gastrointestinal digestion. International Journal of Food Science & Technology, 57(7): 4086–4095.
Dao, Y., Zhang, K., Lu, X., Lu, Z., Liu, C., Liu, M., and Luo, Y. (2019). Role of glucose and 2-oxoglutarate/malate translocator (OMT1) in the production of phenyllactic acid and p-hydroxyphenyllactic acid, two food-borne pathogen inhibitors. Journal of Agricultural and Food Chemistry, 67(20): 5820–5826.
Dewanto, V., Wu, X., Adom, K.K., and Liu, R.H. (2002). Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. Journal of Agricultural and Food Chemistry, 50(10): 3010–3014.
Dhaouadi, K., Meliti, W., Dallali, S., Belkhir, M., Ouerghemmi, S., Sebei, H., and Fattouch, S. (2015). Commercial Lawsonia inermis L. dried leaves and processed powder: phytochemical composition, antioxidant, antibacterial, and allelopathic activities. Industrial Crops and Products, 77: 544–552.
Farinon, B., Felli, M., Sulli, M., Diretto, G., Savatin, D.V., Mazzucato, A., Merendino, N., and Constantini, L. (2024). Tomato pomace food waste from different variants as a high antioxidant potential resource. Food Chemistry, 452: 139509.
Hamad, I., AbdElgawad, H., Al Jaouni, S., Zinta, G., Asard, H., Hassan, S., Hegab, M., Hagagy, N., and Selim, S. (2015). Metabolic analysis of various date palm fruit (Phoenix dactylifera L.) cultivars from Saudi Arabia to assess their nutritional quality. Molecules, 20(8): 13620–13641.
Karagozlu, C., Unal, G., Akalin, A.S., Akan, E., and Kinik, O. (2017). The effects of black and green tea on antioxidant activity and sensory characteristics of kefir. Agro Food Industry Hi Tech, 28(2): 77–80.
Karbasi, M., Yarmand, M.S., and Mousavi, M. (2015). Fermentation potential of Lactobacillus rhamnosus and Lactobacillus acidophilus in date syrup to develop a functional fermented beverage: a comparative study. Journal of Food Processing and Preservation, 39(6): 863–870.
Koma, D., Yamanaka, H., Moriyoshi, K., Ohmoto, T., and Sakai, K. (2012). Production of aromatic compounds by metabolically engineered Escherichia coli with an expanded shikimate pathway. Applied and Environmental Microbiology, 78(17): 6203–6216.
Lajnef, I., Khemiri, S., Ben Yahmed, N., Chouaibi, M., and Smaali, I. (2021). Straightforward extraction of date palm syrup from Phoenix dactylifera L. byproducts: application as sucrose substitute in sponge cake formulation. Journal of Food Measurement and Characterization, 15(5): 3942–3952.
M’hir, S., Rtibi, K., Mejri, A., Ziadi, M., Aloui, H., Hamdi, M., and Ayed, L. (2019). Development of a novel whey date beverage fermented with kefir grains using response surface methodology. Journal of Chemistry, 2019: 1218058.
Majnooni, M.B., Ghanadian, S.M., Mojarrab, M., Bahrami, G., Mansouri, K., Mirzaei, A., and Farzaei, M.H. (2023). Journal of Food Biochemistry, 2023: 5521661.
O’Reilly, E. and Turner, N. (2013). Biocatalytic retrosynthesis. Nature Chemical Biology, 9: 285–288.
Oracz, J., Zyzelewicz, D., and Nebesny, E. (2015). The content of polyphenolic compounds in cocoa beans (Theobroma cacao L.), depending on variety, growing region, and processing operations: a review. Critical Reviews in Food Science and Nutrition, 55(9): 1176–1192.
Ozcan, T., Sahin, S., Akpinar‐Bayizit, A., and Yilmaz‐Ersan, L. (2019). Assessment of antioxidant capacity by method comparison and amino acid characterisation in buffalo milk kefir. International Journal of Dairy Technology, 72(1): 65–73.
Paredes, J.L., Escudero-Gilete, M.L., and Vicario, I.M. (2022). A new functional kefir fermented beverage obtained from fruit and vegetable juice: development and characterization. LWT – Food Science and Technology, 154: 112728.
Patil, S., Pimpley, V., Warudkar, K., and Murthy, P.S. (2022). Valorisation of coffee pulp for development of innovative probiotic beverage using kefir: physicochemical, antioxidant, sensory analysis and shelf life studies. Waste and Biomass Valorization, 13(2): 905–916.
Sabokbar, N. and Khodaiyan, F. (2016). Total phenolic content and antioxidant activities of pomegranate juice and whey based novel beverage fermented by kefir grains. Journal of Food Science and Technology, 53: 739–747.
Sun, B., Ricardo-da-Silva, J.M., and Spranger, I. (1998). Critical factors of vanillin assay for catechins and proanthocyanidins. Journal of Agricultural and Food Chemistry, 46(10): 4267–4274.
Tamang, J.P., Cotter, P.D., Endo, A., Han, N.S., Kort, R., Liu, S.Q., Mayo, B., Westerik, N., and Hutkins, R. (2020). Fermented foods in a global age: East meets West. Comprehensive Reviews in Food Science and Food Safety, 19(1): 184–217.
Tu, C., Azi, F., Huang, J., Xu, X., Xing, G., and Dong, M. (2019). Quality and metagenomic evaluation of a novel functional beverage produced from soy whey using water kefir grains. LWT – Food Science and Technology, 113: 108258.