High-energy ultrasound improves culture activity, polyunsaturated fatty acids and in-vitro protein digestibility in probiotic yogurt

• Published in: Innovative food science & emerging technologies 2024-03, Vol.92, p.103573, Article 103573
• Main Authors: Akdeniz, Vildan, Öcal, Gizem Kaftan, Armağan, Güliz, Akalın, Ayşe Sibel
• Format: Article
• Language: English
• Subjects: Free fatty acid; In vitro protein digestibility; Probiotic; Total amino acid; Ultrasound
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2024.103573

The effect of ultrasound (US) on viable, bacteria counts, free fatty acid and amino acid content and in vitro protein digestibility of set-type probiotic yogurts produced with fortification of milk proteins (caseinate and whey protein concentrate) or skimmed milk powder (SMP) was investigated. US application increased the protein content of probiotic yogurts and enhanced the growth of yogurt bacteria, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and the probiotic bacterium, Bifidobacterium animalis subsp. lactis (BB-12), in yogurt samples. All US-treated groups had higher probiotic counts between 8.44 and 8.61 log cfu/g than their counterpart controls at the end of storage. One- or two- stage US application reduced the saturated fatty acids (SFA) ratio by up to 19% and increased the polyunsaturated fatty acids (PUFA) ratio of probiotic yogurts by up to 40%. At the beginning and end of storage, one-stage US applied Y2 and YP2 groups had the highest PUFA ratio as 36.86, 33.25 and 25.10, 20.03%, respectively, but it did not affect the monounsaturated fatty acids (MUFA) ratio. It also positively affected the in vitro protein digestibility, and total amino acid amounts of probiotic yogurts in pre- and post-digestion. The soluble protein ratios of all US-treated samples were higher both at the beginning and end of storage. Ultrasound is a promising approach in dairy technology. The results obtained in this study can help to improve the probiotic viability, antioxidant capacity, PUFA content, and digestibility of proteins in dairy products by US treatment and provide an opportunity for US-treated dairy products in the functional food market. Ultrasound is a so- called green technology because it is environmentally friendly, and the use of ultrasound in production will positively affect consumer preferences. In addition, obtained data may be beneficial for the industrial use of this technology. •Ultrasound was effective to improve the protein digestibility of probiotic yogurts.•Effect of ultrasound on probiotic bacteria growth was significant.•Ultrasound decreased the SFA ratio and increased the PUFA ratio of probiotic yogurts.•Ultrasound improved the samples' total amino acid amounts pre- and post-digestion.