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:

acceptance, sweetness, yoghurt, β-galactosidase

A study of commercial β-galactosidase stability under simulated in vitro gastric conditions

K. Žolnere¹*, I. Ciproviča¹, A. Ķirse¹ and I. Cinkmanis²

¹Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Food Technology, Rīgas iela 22, LV–3004 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Chemistry, Lielā iela 2, LV–3001 Jelgava, Latvia
*Correspondence: k.zolnere@gmail.com

Abstract:

β-Galactosidase activity in milk may be affected by several factors, such as temperature, pH, milk composition, and metal ions. It is important to note that digestive proteases and gastrointestinal pH can affect enzyme activity during transit through the gastrointestinal tract. For the investigation of commercial β-galactosidase stability in human and animal gastric tracts, human gastrointestinal tract (GIT) models were employed, enabling prediction of enzyme activity under in vivo conditions. The aim of this study was to analyse and compare commercial β-galactosidase stability under simulated in vitro gastric conditions. Commercial enzymes (Ha Lactase 5200 produced by Kluyveromyces lactis and NOLA™Fit5500 produced by Bifidobacterium bifidum expressed in Bacillus licheniformis, Chr. Hansen, Hørsholm, Denmark; GODO-YNL2 produced by Kluyveromyces lactis, Danisco, Copenhagen, Denmark) were used for this study. Commercial enzymes were added to GIT models at 1 and 5 mL L^–1. The enzyme activity was assessed as the percentage of lactose hydrolysis by the enzymes from Kluyveromyces lactis and Bacillus licheniformis using HPLC after digestion. β-Galactosidase extracted from yeast (Kluyveromyces lactis) and bacteria (Bacillus licheniformis) was found to be effective as a strategy for improving lactose tolerance.

Key words: