Some Aspects of Freeze Drying of Dairy Biomaterials
作者:
J.F. Nastaj,
期刊:
Drying Technology
(Taylor Available online 1996)
卷期:
Volume 14,
issue 9
页码: 1967-2002
ISSN:0737-3937
年代: 1996
DOI:10.1080/07373939608917192
出版商: Taylor & Francis Group
关键词: vacuum freeze drying;process/biomaterial parameters;biomaterials quality estimations;dairy biomaterials viability;contact-radiant heating;mathematical model
数据来源: Taylor
摘要:
Different theoretical and experimental aspects of freeze drying of dairy biomaterials are reported. The following dairy biomaterials were chosen for investigations: three kefir bacterial cultures and one bacterial concentrate of a dairy vaccine. Experiments were performed both at one-region conductive or radiative heating and at combined two-region conductive-radiative heating. Emphasis was put on quality interactions between physical and biological properties of the material to be dried and freeze drying process parameters. Qualitative estimations of the following properties of biomaterials: a) colour, b)suppleness to caking and c) suppleness to scraping born the hot surface in dependence with the process parameters were performed using four-step subjective scales. On the basis of this estimations a synthetic quality criterion SQC was defined whose numerical value reflects general product quality. The results of mathematical modelling, numerical solution of the model and comparison with experimental data indicated that the process was heat transfer controlled and that the main factors resulting in good product quality and high SQC are low temperature of the conductive heated surface and vacuum chamber pressure affecting sublimation temperature. The influence of the sample freezing parameters on the elimination of the foaming or puffing and on the product quality was observed and examined. Furthermore, preliminary measurements of the dauy biomaterials viability after freeze drying were presented.
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