Quality improvement of manuka honey through the application of high pressure processing
The quality of honey is known to be compromised when it goes through thermal processing due to its negative impact on the unstable and thermolabile honey components which originated from the nectar and bees themselves. This present work is undertaken to access the use of an emerging food prese...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/1272/1/24p%20NOOR%20AKHMAZILLAH%20MOHD%20FAUZI.pdf http://eprints.uthm.edu.my/1272/ |
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| Institution: | Universiti Tun Hussein Onn Malaysia |
| Language: | English |
| Summary: | The quality of honey is known to be compromised when it goes through thermal
processing due to its negative impact on the unstable and thermolabile honey components
which originated from the nectar and bees themselves. This present work is undertaken to
access the use of an emerging food preservation technique known as “High Pressure
Processing” for treating honey, as an alternative to the conventional thermal processing. In
this thesis, honey quality has been addressed by measuring the effects of high pressure
processing parameters (pressure, time and temperature) on nutritional properties of honey,
namely total phenolic content and antioxidant activity. Honey samples, contained in small
pouches, were subjected to different pressures (200-600 MPa) at close to ambient
temperatures (25-33°C) for different holding times (10 to 30 min). Thermal processing (49-
70°C) was also carried out for comparison purpose. Results demonstrated that high pressure
processing operated at 600 MPa for 10 min has capability to increase significantly the total
phenolic content and antioxidant activity by 47% and 30%, respectively. Besides, the result
showed that high pressure processing can maintain the natural colour of honey which relates
directly to consumer perception, while retaining its shear-thinning behaviour and viscosity
with no significant changes (p > 0.05). High pressure processing can also control
hydroxymethylfurfural (HMF) concentration in honey during process within the standard
limit, 16.93 to 18.76 mg/kg (which is below than the maximum allowed limit of 40 mg/kg).
This work also reveals that high pressure processing can enhance antibacterial activity of
Manuka honey significantly. It shows an increase in the percentage inhibition of
Staphylococcus epidermidis from 64.15 ± 5.86% to 84.34 ± 7.62% when honey was
subjected to 600 MPa. Storage studies for one year at room temperature (25°C) demonstrated
that high pressure-treated samples have a good retention to the physicochemical, nutritional
and rheological properties of honey throughout storage, which confirms that the positive
effect of high pressure on honey is not a temporary effect. Whereas, an insight study on the
safety part showed that the Saccharomyces cerevisiae cell varied linearly with ° Brix,
indicating that food compressibility has a significant role in the microbial inactivation. |
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