EFFECT OF THERMAL PROCESSING AND TYPES OF FOODS ON STABILITY OF COTTONSEED OIL PROPERTIES AND FORMATION OF TRANS COMPONENTS DURING DEEP FRYING | ||||
| Journal of Food and Dairy Sciences | ||||
| Article 4, Volume 25, Issue 2, February 2000, Page 955-974 PDF (683.15 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jfds.2000.258580 | ||||
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| Authors | ||||
| A. M. El-Shawaf,1; A. R.M. El-Zainy2; Mona M. Khalil,3 | ||||
| 1Agric. Indu. Dept. Efficient Productivity Institute, Zagazig Univ., Egypt. | ||||
| 2Home Econ. Dept., Fac. of Specific Educ., Mansoura Univ., Egypt. | ||||
| 3Food Industries Dept., Fac. of Agric., Mansoura Univ., Egypt. | ||||
| Abstract | ||||
| This investigation was carried out to study the effect of heat treatment at 170oC and 200oC at different times (0, 15, 45 and 90 min.) and different types of fried foods (fish, Taamia and Potatoes) on stability of some properties of cottonseed oil before and after thermal processing and identification of cis and trans ethylenic double bonds. The results indicated the following points:- Refractive index increased in oil used for frying fish than both Potatoes and Taamia at 170oC for 90 min., while at 200oC for 90 min. it was higher in fried Potatoes oil than Taamia and fish samples frying oil. Acidity and acid value of deep fried fish oil increased at 170oC for 90 min. than both frying oil of Taamia and Potatoes samples. But at 200oC for 90 min. data revealed that increase of frying oil of Taamia than both Potatoes and Fish samples oil frying. Decreasing iodine value for Fish frying oil than both frying oil of Potatoes and Taamia at 170oC for 90 min. While, data indicated that increase of iodine number at 200oC for 90 min. for Taamia than fish deep frying oil, contrast iodine value decrease at 200oC for 90 min. for Potatoes deep frying oil, due to natural chemical composition. Increased in peroxide value in frying oil of Taamia and Potatoes samples, while peroxide value decreased in oil deep frying of fish samples at 170oC for 90 min. On the other hand data revealed increased in peroxide value in deep frying oil of Taamia than of frying oil of Potatoes and Fish samples at 200oC for 90 min. The red and yellow color increased at 170oC for 90 min. for deep frying oil of Taamia than Potatoes frying oil, while data revealed that darkening of color for oil frying of fish samples. At 200oC for 90 min. red and yellow color was 4.75 and 35 respectively for fried oil of Potatoes, but darkening color for both Fish and Taamia and difficult determination. Using IR and UV instruments showed that trans ethylenic double bonds (carcinogenic) formed at 200oC for 90 min. but disappeared at 170oC at 90 min. for all fried oil samples. The amount of trans-ethylenic double bonds was higher in fried fish, Taamia and Potatoes respectively. The results indicated that successive frying of oil cause formation of carcinogenic and harmful substances to human health for all kinds of foods, especially fish samples, Taamia and Potatoes respectively, for 90 min. at 200oC compared with control samples. The most effect for producing such substances had been due to heat degree and frying periods | ||||
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