The effects of adding Hibiscus sabdariffa L. flowers marmalade on some quality properties, mineral content and antioxidant activities of yogurt

In this study, the effect of Hibiscus sabdariffa L. flowers marmalade (HM) addition at different ratios (0%, 15%, 20%) was determined on the certain quality properties, total phenolic contents, antioxidant activity, mineral composition and heavy metal content of stirred-type yogurts (C, HM15, and HM20). The marmalade addition increased dry matter, ash, titratable acidity and viscosity whereas decreased pH, fat and protein values. HM addition significantly increased the antioxidant properties of yogurt samples. 2,2-Diphenylpicrylhydrazyl radical-scavenging activity, Copper (II) reducing antioxidant capacity and total phenolic content were found to be in the range of 5.92-26.73 mg TE/100 g, 4.88-15.03 mg TE/100 g, and 5.57-14.69 mg GAE/100 g, respectively. There were no statistically differences between control and HM-added groups in terms of lactic acid bacteria (LAB) counts, also in all samples the total LAB count was above 6 Log cfu/g during the storage. Fe, Mn, B, and Ba mineral values of samples with HM were higher than control sample. Cd, As, Hg and Li heavy metals were not detected in any of the samples, consequently results were within reliable limits reported by JECFA (Joint FAO/WHO Expert Committee on Food Additives) and Turkish Food Codex. As a result of the sensory evaluation, the samples containing 20% HM generally received higher scores than the samples containing 15% HM. Considering all the parameters, it was concluded that HM yogurts can be used as a different type in the functional yogurt industry due to its pleasant and characteristic taste.

Automated summary

The addition of Hibiscus sabdariffa L. flowers marmalade (HM) to stirred-type yogurts showed a significant increase in antioxidant properties and certain quality properties, while decreasing pH, fat, and protein values. HM yogurts had higher mineral values and within reliable limits for heavy metal content. Overall, the sensory evaluation indicated that higher percentage of HM addition resulted in better scores, suggesting it can be used as a different and functional yogurt type in the industry.