Improvement of Physicochemical Properties of RBD Palm Olein Blended with Soybean Oil for Deep-Fat Frying
The quality changes of refined, bleached and deodorised palm olein (RBDPOo), soybean oil (SBO) and their blends during intermittent deep-fat frying at 180±5°C for 5h per day for 5 consecutive days were studied. The shelf-life of potato chips used for frying was also investigated. The results show...
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| Format: | Thesis |
| Language: | English English |
| Published: |
1999
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8410/1/FSMB_1999_14_A.pdf |
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| Summary: | The quality changes of refined, bleached and deodorised palm olein (RBDPOo),
soybean oil (SBO) and their blends during intermittent deep-fat frying at 180±5°C for
5h per day for 5 consecutive days were studied. The shelf-life of potato chips used for
frying was also investigated. The results showed that the physicochemical properties of
SBO were improved by blending with RBDPOo in terms of resistance to oxidation,
iodine value (IV), anisidine value (AnV), foaming tendency, % polar component and
polymers content. However, SBO also contributed to RBDPOo with respect to colour,
viscosity, free fatty acids (FF A) content and smoke point. Sensory evaluation showed
that potato chips fried in both of RBDPOo and SBO were equally preferred by the
panellists. Shelf-life stability of the fried potato chips indicated that chips fried in
RBDPOo were better than that fried in SBO. The blends of RBDPOo : SBO were
improved with increasing proportion of RBDPOo. The observation showed that there were minimal effects on the rate of development of rancidity in the fried product
beyond the fourth day of frying in all blends.
The changes of RBDPOo with added TBHQ and (X-tocopherol during deep-fat
frying were also studied. Addition of antioxidants resulted in improved oxidative
stability. TBHQ was more effective in reducing the level of FF A, polar component and
polymers and decreased the rates of change in IV and the ratio of C18:2/C16:0. (Xtocopherol
was more effective in reducing AnV and totox values. However, adding
antioxidants caused darkening of oils and increased the formation of foam during deep fat
frying.
Differential scanning calorimetry (DSC) was also used to monitor IV, peroxide
value (PV), AV and FFA of frying oils. The heating thermogram was from -50 to 80°C
at a heating rate of 5°C/min, whereas, the cooling thermogram was at the same rate
from 80 to -50°C. Stepwise multiple linear regression (SMLR) analysis showed that
peak characteristics, namely peak temperature, enthalpy and peak height of heating and
cooling thermo grams can predict the parameters such as IV, PV, AV and FFA of the
samples with the coefficient of determination (R2) at least 0.9300. Thus, this study
showed that DSC method can monitor these quality parameters of fried oils to replace
wet chemical methods which involve a large number of toxic and environmental
unfriendly solvents and reducing the labour cost as well. |
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