Food Sci Nutr. 2018;6:492–502.
Received: 8 October 2017
Revised: 24 November 2017
Accepted: 1 December 2017
The combined effect of probiotic cultures and incubation final
pH on the quality of buffalo milk yogurt during cold storage
| Fehmi Yazici
| Haci Ali Gulec
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
© 2017 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
Engineering Faculty, Department of Food
Engineering, Trakya University, Edirne, Turkey
Engineering Faculty, Department of Food
Engineering, Ondokuz Mayis University,
Abdullah Akgun, Engineering Faculty,
Department of Food Engineering, Trakya
University, Edirne, Turkey
The combined effects of starter culture type (SCT) and incubation final pH (IFpH) on
the physicochemical and organoleptic properties of buffalo milk yogurt containing
3 g·100 g
milk fat were investigated throughout 20 days of storage at 4°C. The post-
acidification kinetics fitted to zero- order reaction for all buffalo milk yogurt samples.
The reaction rate constants of the buffalo milk yogurt samples containing YC- X11,
ABY- 2, and ABT- 4 cultures were 0.010, 0.007, and 0.004 g·100 g
tively. Regardless of the IFpH, the absence of Lactobacillus delbrueckii subsp. bulgaricus
in the starter culture increased the syneresis. L*, a*, and b* values were not affected by
the IFpH and the SCT. ABY- 2 culture increased the amount of organic acids during
cold storage in comparison with the YC- X11, while its effect on the proportions of
saturated and unsaturated fatty acids was not significant. The results of sensory evalu-
ation revealed that a more acceptable buffalo milk yogurt can be manufactured by
using probiotic ABY- 2 culture.
buffalo milk yogurt, cold storage, incubation pH, starter culture
1 | INTRODUCTION
Final composition and physicochemical and sensory aspects of a fer-
mented milk product such as yogurt are influenced mainly by chemi-
cal composition of milk (Akgun, Yazici, & Gulec, 2016) and processing
conditions (Nguyen, Ong, Kentish, & Gras, 2014). The effects of milk
composition on the mentioned properties of buffalo milk yogurt are
well described in our previous study (Akgun et al., 2016). Starter cul-
ture type (SCT) and incubation final pH (IFpH) are considered as other
important factors which affect overall quality of buffalo milk yogurt
during cold storage.
Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bul-
garicus are typical strains in yogurt manufacturing. Yogurt that contains
probiotic bacteria such as Lactobacillus acidophilus and Bifidobacteria
(Tamime & Robinson, 1999) is popular in dairy industry due to their
health- promoting properties (Ravula & Shah, 1998). Also, a wide range
of products with different flavors, textures, and consistencies were
obtained by mixed strains of these microorganisms (Mckinley, 2005).
Olson and Aryana (2008) stated that an excessively high inoculated
level of L. acidophilus prolonged the incubation time and resulted in an
inferior quality in cow milk yogurt. Up to now, other studies on pro-
duction of bioyogurt have mainly focused on evaluating the viability
of probiotic bacteria in fermented milk products and their potential
health benefits (Maragkoudakis et al., 2006). However, to the best of
our knowledge, there is no comprehensive study on the evaluation of
the effects of SCT and IFpH on the physicochemical and organoleptic
properties of buffalo milk yogurt during cold storage. The process vari-
ables affecting the gel formation and syneresis in buffalo milk yogurt
are also not well understood.
The combined assessment of organic and fatty acid profiles in
yogurt with the activity of different starter cultures is a key issue to
identify the effect of SCT on the flavor and aroma characteristics of
the final product. The organic acid profile in a fermented dairy food
is an indicator of the metabolic activity of added bacterial cultures