Nauka Przyroda Technologie

2017 volume 11 issue 1 #10 , DOI: 10.17306/J.NPT.2017.1.10

Paulina Bierzuńska, Łukasz K. Kaczyński, Dorota Cais-Sokolińska, Bartosz Kulczyński

Texture profile of kefir and yogurt with modified configuration of proteins

Summary.

Background. The composition of processed milk and technical and technological conditions of its further processing in the production of fermented milk have a significant impact on the development of its texture. The aim of this study was therefore to assess texture profile of kefir and yogurt made from skimmed milk with varying proportions of casein and whey protein, being an indicator of its quality.

Material and methods. Kefir and yogurt with a 14.5% content of dry matter were prepared with an addition of skim milk powder and whey protein concentrates with varying proportions of protein. Selected texture parameters were measured using a TA.XT-plus texture analyser and the Texture Exponent E32 software using back extrusion.

Results. It was found that the greater the whey protein content, the lesser the firmness of model kefir and yogurt from skimmed milk. Regardless of the ratio of casein to whey protein (CN : WP) it was found that after 21 days kefir and yogurt from skimmed milk are firmer than immediately after production, and only yogurt exhibits greater cohesiveness. The viscosity index of yogurts with the smallest ratio of casein to whey protein (1 : 1.9) after 21 days was by 52% higher than it was after production. In the yogurt with the greatest CN : WP ratio (1 : 0.2) the viscosity index increased by 33%.

Conclusions. The greater the proportion of whey protein to casein, the lesser its firmness and cohesiveness and the looser the consistency of kefir with 14.5% dry matter. The viscosity index of kefir with WPC 80 was 70% lower than that with SMP. No differences in texture were found between kefir from unthickened milk and that from thickened milk with the largest share of whey protein.

Key words: kefir, yogurt, fermented milk, whey protein concentrates, texture

Full text available in English in Adobe Acrobat format:
https://www.npt.up-poznan.net/pub/art_11_10.pdf

Streszczenie w języku polskim:
https://www.npt.up-poznan.net/tom11/zeszyt1/streszczenie-10.html

Corresponding address:
Paulina Bierzuńska
Katedra Technologii Mleczarstwa
Uniwersytet Przyrodniczy w Poznaniu
ul. Wojska Polskiego 31/33
60-624 Poznań
Poland
e-mail: paulina.bierzunska@up.poznan.pl

Accepted for print: 31.03.2017