Design of probiotic yoghurt with the addition of royal jelly

Ivelina G. Peykova-Shapkova; Mihaela G. Ivanova; Ivan G. Ivanov; Natalina K. Panova; Krastena T. Nikolova; Yulian D. Tumbarski

doi:10.35219/foodtechnology.2026.1.03

Ivelina G. Peykova-Shapkova Department of Milk and Dairy Products, University of Food Technologies, 26, Maritsa Blvd., 4002, Plovdiv, Bulgaria https://orcid.org/0009-0007-3449-2698
Mihaela G. Ivanova Department of Milk and Dairy Products, University of Food Technologies, 26, Maritsa Blvd., 4002, Plovdiv, Bulgaria https://orcid.org/0000-0002-6041-8471
Ivan G. Ivanov Department of Organic Chemistry and Inorganic Chemistry, University of Food Technologies, 26, Maritsa Blvd., 4002, Plovdiv, Bulgaria https://orcid.org/0000-0002-6826-2723
Natalina K. Panova Department of Physics and biophysics “Prof. Dr. Paraskev Stoyanov”, 55, "Professor Marin Drinov" street, 9002 Medical University,Varna, Bulgaria https://orcid.org/0000-0003-2807-6026
Krastena T. Nikolova Department of Physics and biophysics “Prof. Dr. Paraskev Stoyanov”, 55, "Professor Marin Drinov" street, 9002 Medical University,Varna, Bulgaria https://orcid.org/0000-0002-2617-4776
Yulian D. Tumbarski Department of Microbiology and Biotechnology, University of Food Technologies, 26, Maritsa Blvd., 4002, Plovdiv, Bulgaria https://orcid.org/0000-0003-1674-5333

DOI: https://doi.org/10.35219/foodtechnology.2026.1.03

Keywords: yoghurt, royal jelly, probiotic yoghurt, probiotic royal jelly yoghurt

Abstract

This study aimed to develop a probiotic yoghurt enriched with royal jelly to enhance its nutritional and functional qualities. The effects of incorporating Lacticaseibacillus casei RC-1 and royal jelly on the physicochemical, antioxidant, microbiological, and rheological properties of yoghurt were evaluated over 21 days of refrigerated storage. Three yoghurt formulations were designed and tested: control yoghurt with classic starter culture (Yc), yoghurt with classic starter culture and probiotic strain (Ypro), and yoghurt with classic starter culture, probiotic strain and royal jelly (Ypro+RJ). Parameters such as pH, titratable acidity, water content, water holding capacity (WHC), fat content, colour (L*, a*, b*), total polyphenols, antioxidant activity (DPPH, FRAP), and microbial counts were analyzed. Ypro+RJ maintained the highest pH and lowest acidity, indicating reduced acidification. WHC improved in all samples, with Ypro+RJ reaching the highest value. Colour shifts were minimal, suggesting little perceptible difference. Ypro+RJ had the highest polyphenolic content and strongest antioxidant activity, reflecting a synergistic effect between the probiotic and royal jelly. Microbial analysis showed increased lactic acid bacteria (LAB) counts in Ypro and Ypro+RJ, while the total plate count and yeast/fungi counts remained within safe limits. Rheological testing revealed shear-thinning behavior in all samples. Overall, royal jelly addition enhanced the yoghurt’s functional properties, boosting antioxidant activity, microbial viability, and storage stability. These results suggest that royal jelly-enriched probiotic yoghurt could serve as a next-generation functional food with potential health and consumer benefits.

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