The Potential of Olive Leaf Extract as a Functional Ingredient in Yoghurt Production: The Effects on Fermentation, Rheology, Sensory, and Antioxidant Properties of Cow Milk Yoghurt.

Katarina Lisak Jakopović,Rajka Božanić,Maja Repajić,Katarina Filipan,Marijana Blažić,Irena Barukčić

doi:10.3390/foods11050701

Katarina Lisak Jakopović, Rajka Božanić + Show 4 more

Open Access

https://doi.org/10.3390/foods11050701

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Abstract

Background: Yoghurt has been traditionally consumed for its high nutritional value and health-promoting benefits. The addition of plant extracts as a source of phenolic compounds and bio-flavonoids has attracted much attention recently since milk and dairy products are deficient in these health-protecting components. Accordingly, olive leaf extract (OLE) has been considered due to the presence of bioactive compounds, primarily polyphenols. Thus, the aim of this research was to investigate the possibility of adding OLE into cow milk yoghurt as a potential functional ingredient. Methods: Yoghurts enriched with OLE (1.5, 3, and 5% v/v) were produced and compared with yoghurt without OLE. In all samples acidity, viscosity, colour, syneresis, water holding capacity (WHC), microbiological parameters, sensory properties, total phenols, and antioxidant activity (DPPH and FRAP methods) were determined. Results: The addition of OLE resulted in shorter fermentation and lower pH, but it had no adverse effect on the viability of yoghurt starter bacteria. OLE-enriched yoghurts showed increased syneresis, higher total phenols content, and antioxidant activity, while WHC and viscosity decreased. Sensory properties were slightly poorer for yoghurts containing higher OLE concentrations. Considering all of the obtained results, the addition of 1.5% OLE appeared to be optimal.

Highlights

Modern consumers are increasingly aware of the important role that a well-balanced daily diet plays in preventing the occurrence of human health disorders
The objectives of this study were to investigate the effect of adding olive leaf extract (OLE) on the fermentation process and viability of lactic acid bacteria contained in yoghurt culture, rheological, sensory, and antioxidant properties of yoghurt, as well as to determine the most appropriate levels of supplementation based on the obtained data
The content of total phenols and the values of antioxidant activity (Figure 4) demonstrated that the supplementation of yoghurt with OLE represents an efficient pattern for enhancing its antioxidant capacity and biological value

Summary

Introduction

Modern consumers are increasingly aware of the important role that a well-balanced daily diet plays in preventing the occurrence of human health disorders. Regular consumption of functional foods containing specific components with a positive impact on human health has become unquestionable, and consumers are willing to pay up to 10–50% price premium for nutritionally enhanced products [2] Fermented dairy products such as yoghurt or kefir have traditionally been considered foods of high nutritional value and numerous health-promoting benefits, which makes them one of the most frequently consumed functional foods in general. The addition of plant extracts as a source of functional ingredients such as phenolic compounds and bio-flavonoids has gained considerable attention, since milk and dairy products are deficient in such valuable, health-protecting components [4]. The addition of plant extracts as a source of phenolic compounds and bio-flavonoids has attracted much attention recently since milk and dairy products are deficient in these health-protecting components. OLE-enriched yoghurts showed increased syneresis, higher total phenols content, and antioxidant activity, while

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