EFFECT OF ADD SOME AROMATIC PLANTS ON THE STABILITY OF THE OXIDE FRYING OILS

The present study was carried out to achieve the following objectives:

Studying the time-temperature relationships during frying operations using designed frying protocol.
Investigating the effect of frying process on the quality parameters of frying oilused. The different suggested treatments that carried out in this investigation could be summarized with their abbreviations as follows:

Treatment (T): Control Without any additives
Palm olein (PO)
T1 PO+ 0.2% rosemary extracted (RE)
T2 PO+ 0.2% Sage extracted (SE)
T3 PO+ 0.2% Basil extracted (BE)
T4 PO+ 0.2% Butylated hydraxy touloene (BHT). The palm olein was heated to 60°C before addition of oil extracts (0.2%) rosemary; sage or basil then stirred to ensure that it was completely dissolved. BHT- containing palm olein (0.02%) and control samples (without any antioxidant) were used as positive and negative control. All frying oil samples were heated at frying temperature in about 2 minutes to elevate temperature from 25 to 180°C, followed by addition of potato chips at a rate of 400 g in 5 liters frying oil for 21/2 minutes to complete frying process in the 1st cycle of frying. The 2nd (heating and cooling) cycle of frying process was carried out after 1/2 min. When the frying oil temprature raised again from about 170 to 180°C and potato chips was added at a rate of 400 g to 4970cm3 frying oil no need to oil loss compensation due to loss of this small amount of frying oil (0.6%). This process was repeated 10 times at the 1st day of the experiment. The experimental ended after 50 frying processes at the 5th day. Samples were withdrawn at 0 time (60°C) then after 10, 30 and 50 frying processes at the 5t day. Samples size was 250ml for chemical and physicochemical analysis and 250 ml for biological assay. Deep frying experiments were carried out simultaneously using an aluminium open fryer with a concave shape which is almost used in all frying restaurants in Egypt and mainly sold in El-Qamalyia district. This frying pan capacity was 10 litre oil and equipped with autolift aluminum basket. The oil in each fryer was filtered to remove debris using separate filters.The same frying process was repeated three times in three consecutive weeks and withdrawn samples from each trial were mixed together to form a representative composite sample. After frying operations, the frying products were weighed and after each 10 fryings, samples were withdrawn and stored in brown bottles in a deep freezer at -20°C until analysis. Oil (250m1) was sampled from each frying medium to represent 0, 10, 30and 50 frying cycles, consecutive up to 5 days, and was kept in amber bottles. Oil samples were flushed with slow bubbles of nitrogen free the botton of the bottles and stared in freezer at 20°C for physical and chemical analysis. The same sample weight was also with drown for biological evaluation.
After frying, the chips were removed from the frying pan and sensory evaluation was conducted in the same day using all batches of potato chips (0, 10, 30 and 50 fryings). The ratio between potato weight and frying oil volume (w/v) was almost stable depending on oil loss two samples of oil, each weighing 225gm, one for phesical and chemical analysis and the 2nd one for biological assay were taken. The whole procedure was repeated consecutively for 7 days. Results showed that. The No. of frying (times of frying) has a significant effect on peroxide value of all samples. The peroxide values increased with increasing no. of fryings until the 50th frying. artificial (BHT) or natural (rosemary, sage and basil) did not have the ability to inhibit peroxide formation even after only 10 fryings. On the other side, these antioxidants reduced the percentage of peroxide formation from about 65% to only 20-22% (rosemary, sage, basil and BHT). Ansidine value was clearly affected by No.of fryings as a general trend in case of T1, T2and T3 similar to that of control one. it could be report that using chemical (artifichial) antioxidant did not prevent the ditremental effect of frying times compaired with using natural antioxidants. On the other hand, use of natural or artificial antioxidants (T1, T2, T3, T1 and T4) minimized ansidine value by about 1.1 folds from control sample at any number of frying. Totox value of unheated palm olein with or without antioxidants was ranged between 17.90 to 20.17. It is of great importance to mention that there was no significant difference between all samples either untreated or treated with natural or artificial antioxidants at F0.
Addition of herb extracts (0.2%) was significantly natural or articifical extracts lowered the totox value significantly (P≤ 0.05) compared to the control after 10 fryings with about 1.2 folds (for all treatments) less than control one. Totox value of unheated palm olein with or without antioxidants was ranged between 17.90 to 20.17. It is of great importance to mention that there was no significant difference between all samples either untreated or treated with natural or artificial antioxidants at F0.
Addition of herb extracts (0.2%) was significantly natural or articifical extracts lowered the totox value significantly (P≤ 0.05) compared to the control after 10 fryings with about 1.2 folds (for all treatments) less than control one. Iodine number did not affect by the type of antioxidant use as seen at F0 treatment; i.e. no significancy was found (values were around 56-58). Thiobarbituric acid number (TBA) value did not affect by only the type of antioxidant (as seen at F0 treatment). But, when frying process was taken place the TBA value was increased by about 2 folds after 10 fryings for all treatments. After 30 times of frying, the increasing in TBA value reached to be 3 folds for all treatments and sharply increased to be about 4.5 folds that of their initial values (at F0) for all treatments. Acid value of various treatments was praparationaly correlated with No. of fryings. A significant difference was also noticed between treatments. The (F50) treatment recorded the highest acid value. Frying times (No. of fryings) were clearly affected scuh parameter (viscosity) in case of T3 and T4 treatments. It reached to 107.14 and 109.13 in T3 and T4, respectively after 50 times of frying. Meanwhile, it was ranged between 84.41 to 96.89 in other treatments after the same No. of fryings. the higher the frying times, the higher the polar value; i.e. there is a proportional relationship between polar value and number of fryings . No significant differences were detected between treatments as affected by using natural (Sage, rosemary and basil) and or artificial antioxidant (BHT). Such finding was noticed in all organalyptially evaluated parameters, i.e. appearance, odor, color, taste, texture and overall acceptability. Mean values were between 6.33-8.33. It could be concluded that using antioxidant either natural or artificial one did not organaloptically effect by type of antioxidant when the product or used oil were considered.