Acceptance of low-sugar yoghurt among Latvian teenagers

J. Zagorska*, I. Ciprovica, E. Straumite and K. Majore

Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Rigas iela 22, LV3004 Jelgava, Latvia
*Correspondence: jelena.zagorska@llu.lv

Abstract:

Over a thousand year history, yoghurt has become one of a widely consumed product in the world. Its reputation as a healthy food has been undermined recently by concerns over the high sugar content. The majority of consumers expects and prefers yoghurts to be sweet. However, governments across Europe are calling for significant cuts in the amount of added sugar used in yoghurt production. The aim of the study was to evaluate the acceptance of low-sugar yoghurt produced by different commercial β-galactosidases by teenagers. Standardised milk with fat content 2.0% (SC Tukuma piens) was pasteurized at 95 ± 1 °C 5 min, cooled down till 43 ± 1 °C and fermented with β-galactosidase and starter YC-X11 (Chr. Hansen, Denmark) and fermented till pH 4.50 ± 0.20. Different commercial β-galactosidases: Nola™ Fit 5500, Ha-Lactase 5200 (Chr. Hansen, Denmark), GODO-YNL2 (Danisco, Denmark) and BrennZyme (Brenntag PolskaSp, Poland) were used. Fermented samples were gently mixed and cooled down till 6 ± 1 °C and 5% (w/w) of sugar was added to each sample. Sensory evaluation of the yoghurt’s samples was performed by teenagers (14–18 years, n = 50) at Aizputes Secondary School (Latvia). Lactose and monosaccharides concentration prior to sugar addition was detected by HPLC (Shimadzu LC 20 Prominence, Japan).
The lactose hydrolysis into glucose and galactose by the use of β-galactosidase helps to increase sweetness through an occurrence of natural sugars in milk. During sensory evaluation, teenagers admitted the yoghurt with reduced sugar as sweet, significantly sweeter (P < 0.05) was yoghurt sample with Nola™ Fit 5500. The results demonstrated that it is possible to reduce sugar in yoghurt production and to gain consumer acceptance through the occurrence of glucose and galactose, but it is problematic to offer lactose-free or reduced lactose products to consumers without lactose intolerance.

Key words:

Enrichment of the low-fat yoghurt with oat β-glucan and EPS-producing Bifidobacterium bifidum improves its quality

M. Ibrahim¹²*, N. Barakova¹ and I. Jõudu²³

¹ITMO University, Faculty of Food Biotechnology and Engineering, Department of Food Biotechnology (Vegetable stock), Lomonosova 9, RU191002 Saint-Petersburg, Russia
²Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Chair of Food Science and Technology, Kreutzwaldi 56/5, EE51006 Tartu, Estonia
³Estonian University of Life Sciences, ERA Chair for Food (By-) Products Valorisation Technologies of the Estonian University of Life Sciences, Kreutzwaldi 56/5, EE51006 Tartu, Estonia
*Correspondence: monikanbil@yahoo.com, monica.nabil@student.emu.ee

Abstract:

The addition of β-glucan or EPS-producing bacteria is mainly used to improve the quality and the acceptability of low-fat yoghurt. The purpose of this study was to investigate the effect of adding β-glucan, EPS-producing Bifidobacterium bifidum, or both on physical properties, fermentation time, and organoleptic criteria of low-fat yoghurt, additionally to the viability of L. bulgaricus and B. bifidum. Two types of low-fat yoghurt (1.5% fat) were prepared, with the addition of standard oat β-glucan by 0.15% or without its addition. Each type of yoghurt mixture was inoculated with two kinds of starters: traditional and probiotic (B. bifidum) culture. The physicochemical properties, the count of viable bacterial starter culture, and the organoleptic evaluation for all yoghurt types were evaluated after storage 24 h at 4 °C. Moreover, the fermentation time was monitored. The incorporation of both β-glucan and EPS in yoghurt resulted in the highest viscosity (13.7 mPa.s) and WHC (55.94%), besides to the lowest syneresis (28.47%). The acidity and pH of the yoghurt samples were significantly affected (p > 0.05) by the β-glucan addition. The yoghurt type Bifidobacterium glucan had the shortest fermentation time (215 min), and the maximum viability of both B. bifidum (7.63 Log CFU g^-1) and L. bulgaricus (7.50 Log CFU g^-1). The β-glucan had a pronounced effect on the overall acceptability of yoghurt more than the EPS. In conclusion, enriching the low-fat yoghurt with oat β-glucan and EPS-producing B. bifidum is the highest effective method for improving the yoghurt’s quality and the viability of probiotics.

Key words:

acceptability, B. bifidum, low-fat, oat β-glucan, quality, viability, yoghurt