Heat treatment (around 50° / C) is a major step in honey filling and packaging that
is applied before filtration to decrease viscosity, reduce the moisture level, to
destroy yeasts, liquefy crystals and delay crystallization. As a result, formation
of Hydroxy Methyl Furfural (HMF), decrease in enzymatic activity, color
deterioration, decrease in viscosity and many other structural changes are
observed. HMF is produced as a result of Maillard reaction and/or hexose
dehydration -which is undesirable-, practically, it is found in fresh honey in low
levels, and increases due to heat treatment, storage temperature, pH (acidity)
and sugar concentration of honey. HMF level and diastase number are
important quality parameters and shelf life indicators of honey. Alternatives of
v
heat treatment may be the use of ultrasound and high hydrostatic pressure
(HHP) to decrease viscosity, liquefy honey and thus minimise adverse affects of
heat treatment. Therefore, the aim of this study is to evaluate the effect of HHP
(220-330 MPa, 50-60° / C, time) and ultrasound (24 kHz) on liquefaction and
quality parameters (HMF, diastase number, color and viscosity) of different
honey varieties (sunflower, cotton and canola) and to compare the changes with
heat treated (50° / C and 60° / C, time) and untreated honey. Based on the results of
the chemical and physical analysis, for HHP treatment the best treatment
combination was determined as 220 MPa, 50° / C, 106 min. For ultrasound
treatment the best treatment combinations were determined as 7 mm probe- 0.5
cycle (batch) applications. On this basis the study points out that Ultrasound
and HHP can be suggested as alternative methods to traditional thermal
treatment for the liquefaction of honey crystals. When compared to thermal
treatment, Ultrasound is advantageous in shorter application times, slight
changes in quality parameters and ease in operation. HHP treatment is also an
alternative method with shorter application times and lower HMF values.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12611606/index.pdf |
| Date | 01 February 2010 |
| Creators | Basmaci, Ipek |
| Contributors | Alpas, Hami |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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