Izvorni znanstveni članak
The influence of whey protein concentrate addition on the viscosity and microbiological quality of yoghurt during storage
Rajka Božanić
orcid.org/0000-0002-3387-0315
; Prehrambeno-biotehnološki fakultet Sveučilišta u Zagrebu, Pierottijeva 6, 10000 Zagreb
Ljubica Tratnik
Olivera Marić
Sažetak
In this work the influence of whey protein concentrate addition on viscosity and microbiological quality of yoghurt during nine days of storage was investigated. In the preliminary experiment on the basis of sensory evaluate the optimal quantity of whey protein concentrate addition in milk (1%) was determinated. Fermentation of milk samples (with and without whey protein concentrate addition) at 42 ° C and pH of approximately 4.6, was conducted until coagulum appearance. Whey protein concentrate addition had no influence on duration of fermentation (5 hours and 42 minutes for both samples). After fermentation yoghurt samples were kept in refrigerator (at +8 °C) during nine days, and analysed at regular intervals (1, 3, 6, 9 days). The acidity, viable count change, viscosity and sensory characteristics were conducted. During storage the viable count in yoghurt samples, with whey protein concentrate addition, increased showing the maximum during 3th day (logN=8.84/ ml), and after that started to decrease. Viable count in control yoghurt samples did not change significantly during storage, while viable count of lactobacilli was significantly lower. The viscosity of the samples with whey protein concentrate addition was higher than that of control samples. The difference in consistency and taste between produced beverages was not significantly expressed. The best sensory scores (19.7-20.0) of the samples were obtained during third day of storage and remained very high (19.7-19.9) until ninth day of storage.
Ključne riječi
yoghurt; whey protein concentrate; viscosity; microbiology; sensory evaluation
Hrčak ID:
93079
URI
Datum izdavanja:
15.3.2000.
Posjeta: 1.323 *