Kesan Parameter-Parameter Penggorengan Ke Atas Perubahan-Perubahan Fizikal Keropok Dan Papad Semasa Penggorengan Celup

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Date
1995-05
Authors
Chanderan K, Vasanti Nair
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Abstract
On deep-fat frying, the half-products of keropok and papad, undergo physical changes such as moisture loss (ML), oil absorption (OA) and linear expansion (LE) which give the end-products their desirable characteristics. Studies were conducted to investigate the effects of the frying parameters of oil temperature (T), time (t) and initial moisture content (M) of the half-products, and the interrelationships of their effects, on these physical changes. A finding common to both products is that little or noML, OA or LE occurred when T, t or M was below a critical level, designated as Tcr ' tcr and Mer' respectively. On exceeding Tcr ' tcr and Mcr ' these physical changes increased drastically before reaching either a plateau or a peak. The critical frying temperature (T cr ) of keropok was found to be closely related to its heat of desorption at any particular initial moisture content since deep-fat : , frying can be approximated to a drying or moisture removal LUL~ ~U~g~~L~ lna~ enougn energy has to be provided to overcome the heat of desorption before any significant physical change can take place. Moisture lost was quantitatively replaced by the oil absorbed, with ML and OA exhibiting excellent correlation. The major factor responsible for LE was rapid vaporization of --water which occurred under conditions where all three critical levels were exceeded. The optimum frying conditions tri attain maximum LE for (a) keropok are T = 190- 200oC, M = 15-20% (d.b) and t = 40 s, and (b) papad are T = 190-200oC, M = 10-15% (d.b.) and t = 20 s. The microstructural changes of papad during deep-fat frying under different conditions revealed that native starch granules played little, if any, role in linear expansion of the product. Rather, expansion was due the stretching of protein-mucilage matrix surrounding the starch granules as a result of rapid vaporization of water .
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Technology Industry , Effects Of Frying Parameters
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