Effect of ultraviolet irradiation with dean vortex technology on quality of pineapple-mango juice blend
Conventional thermal pasteurisation is more preferable by juice processor in microorganism inactivation due to its effectiveness but results in nutritional and quality degradation. Due to that, the alternative non-thermal technology of ultravioletirradiation (UV-C) gaining interest to minimise th...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/77280/1/FK%202018%20178%20ir.pdf |
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| Summary: | Conventional thermal pasteurisation is more preferable by juice processor in
microorganism inactivation due to its effectiveness but results in nutritional and quality
degradation. Due to that, the alternative non-thermal technology of ultravioletirradiation
(UV-C) gaining interest to minimise the stated effects. Application of UV-C
in single fruit juice already well explored compared to a juice blend. Thus, this present
research aimed to investigate the effect of UV-C on the quality attributes of pineapplemango
juice blend. Pineapple-mango juice blend at blending ratio of (pineapple to
mango) 70:30 (v/v), exhibit best results of ascorbic acid, total phenolic with lowest
turbidity value compared to blending ratios of 50:50 and 30:70. Colour appearance of
pineapple-mango juice blend at all different blending ratios was not significantly
different. Pineapple-mango juice blend at blending ratio of 70:30 were selected for
further preservation treatment. UV-C dosage of 8.38mJ/cm² able to reduce the
microbial load (Escherichia coli O157: H7, total plate count, yeast and mould count) to
safety limit of 5-log reduction. Storage of 9 weeks at 4°C of pineapple-mango juice
blends resulted in significant changes in pH, total soluble solids, turbidity and DPPH
assay (p<0.05) of untreated, thermal and UV-C treated juice. Although, the ascorbic
acid and total phenolic content of UV-C treated pineapple-mango juice blend was
decreasing (p<0.05) the values were higher compared to thermally treated juice. Colour
degradation (lightness, hue, chroma, browning index, colour difference (ΔE) and nonenzymatic
browning) of thermally treated pineapple-mango juice blend was also
prominent in thermally treated juice compared to UV-C treated juice. During storage,
reoccurrence of microbiological activities of UV-C and thermally treated pineapplemango
juice blend observed starting at week 3 and 5 respectively. Kinetic model of ΔE
during storage of the untreated and thermally pineapple-mango juice blend fitted to
zero order model, while UV-C treated fitted to first order. Ascorbic acid degradation of
untreated, UV-C and thermally treated pineapple-mango juice blend best fitted to
modified first order model indicate storage time together with other parameter such as
pH, temperature and oxygen contribute to the degradation rate. The present study
showing promising effect of UV-C treatment in preserving the quality of pineapplemango
juice blend. |
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