Examination of pH, Titratable Acidity and Antioxidant Activity in Fermented Milk, Journal of materials Science and Engineering

Tomovska, Julijana and Gjorgievski, Nikola and Makarijoski, Borche (2016) Examination of pH, Titratable Acidity and Antioxidant Activity in Fermented Milk, Journal of materials Science and Engineering. Journal of Materials Science and Engineering A, 6 (11). pp. 326-333.

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Abstract

As a fermentation medium homogenized and sterilized whole milk is used. The length of the fermentation was 4 hours, symbiosis of Streptococcus thermophilus and Lactobacillus delbruesciissp. Bulgaricus were used, to achieve the isoelectric point of casein 4.6 pH. Monitored parameters were: pH, titratable acidity and antioxidant activity (AOA) in a period of 15 days. It has been determined a decrease of pH value from 6.67 to 4.19, an increase of titratable acidity from 8.0 to 36.07 oSH and an enhancement of AOA from 6.13 to 47.4%.The determination of AOA was accordeda method which is used for different types of food, by using stable 2,2-diphenyl-1-pikrilhidrazil (DPPH) free radical and the absorbance was measured at 517nm on a spectrophotometer Spectroquant Pharo 300, Merck. The neutralization activity of the free radical was expressed as a percentage of inhibition of absorbance of DPPH. Milk fermented with Lactobacillus delbrueckii ssp. Bulgaricus, the highest level of AOA registered immediately after the process of fermentation with a value of 52.44%. The lowest value of AOA for the same symbiosis of cultures was observed at the third day after fermentation process kept at a temperature of 4 °C, with a value of 39.43%. Key words: Yogurt, fermented products, pH, titratable acidity, antioxidant activity.

Item Type: Article
Subjects: Scientific Fields (Frascati) > Agricultural Sciences > Animal and diary science
Scientific Fields (Frascati) > Natural sciences > Chemical sciences
Divisions: Faculty of Biotechnical Sciences
Depositing User: Prof. d-r Borche Makarijoski
Date Deposited: 17 Jun 2020 14:07
Last Modified: 17 Jun 2020 14:07
URI: http://eprints.uklo.edu.mk/id/eprint/5383

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