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Open AccessArticle

Yoghurt-Type Gels from Skim Sheep Milk Base Enriched with Whey Protein Concentrate Hydrolysates and Processed by Heating or High Hydrostatic Pressure

1
Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
2
Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens (NTUA), Laboratory of Food Chemistry and Technology, 5 Heroon Polytechniou Str., Zografos, 15780 Athens, Greece
*
Author to whom correspondence should be addressed.
Foods 2019, 8(8), 342; https://doi.org/10.3390/foods8080342
Received: 30 June 2019 / Revised: 25 July 2019 / Accepted: 9 August 2019 / Published: 12 August 2019
(This article belongs to the Special Issue Novel Processing Technology of Dairy Products)
An objective of the present study was the enrichment of skim sheep yoghurt milk base with hydrolysates (WPHs) of whey protein concentrate (WP80) derived from Feta cheesemaking. Moreover, the use of high hydrostatic pressure (HP) treatment at 600 MPa/55 °C/10 min as an alternative for heat treatment of milk bases, was studied. In brief, lyophilized trypsin and protamex hydrolysates of WP80 produced under laboratory conditions were added in skim sheep milk. The composition and heat treatment conditions were set after the assessment of the heat stability of various mixtures; trisodium citrate was used as a chelating agent, when needed. According to the results, the conditions of heat treatment were more important for the physical properties of the gel than the type of enrichment. High pressure treatment resulted in inferior gel properties, irrespective of the type of enrichment. Supplementation of skim sheep milk with whey protein hydrolysates at >0.5% had a detrimental effect on gel properties. Finally, skim sheep milk base inoculated with fresh traditional yoghurt, resulted in yoghurt-type gels with high counts of Lb. delbrueckii subsp. bulgaricus and Str. thermophilus -close to the ideal 1:1- and with a high ACE inhibitory activity >65% that were not essentially affected by the experimental factors. View Full-Text
Keywords: high hydrostatic pressure; whey protein hydrolysates; sheep milk; yoghurt; ACE inhibitory activity; gel properties; heat stability; traditional yoghurt starter; biofunctionality high hydrostatic pressure; whey protein hydrolysates; sheep milk; yoghurt; ACE inhibitory activity; gel properties; heat stability; traditional yoghurt starter; biofunctionality
MDPI and ACS Style

Sakkas, L.; Tzevdou, M.; Zoidou, E.; Gkotzia, E.; Karvounis, A.; Samara, A.; Taoukis, P.; Moatsou, G. Yoghurt-Type Gels from Skim Sheep Milk Base Enriched with Whey Protein Concentrate Hydrolysates and Processed by Heating or High Hydrostatic Pressure. Foods 2019, 8, 342.

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