Estimation of the Oxidative Deterioration of Turbine Oil Using Membrane Patch Color

Lubricating oils degrade into two main products: oxidation products and solid particles. Oxidation products, called varnish, of turbine oils for power generation have become a particularly serious problem in recent years. The first step in determining the potential to produce varnish is to determine the remaining life of the antioxidant in the oil, but even though turbine oil may have antioxidants of sufficient longevity, varnish problems still occur frequently. Accordingly, to prevent varnish, it is necessary to diagnose oil oxidation products. Thus, the authors have developed a diagnostic method using membrane patch color, but the relationship between membrane patch color and the remaining life of turbine oils has yet to be clarified. This paper investigates a new method for estimating the oxidative degradation of turbine oils that uses membrane patch color and the dry turbine oxidation stability test (dry TOST) based on oxidation products and the remaining life of the turbine oils. Sample oils were prepared and degraded by oxidation in the laboratory using a dry TOST apparatus, and the membrane patch color was measured using a colorimetric patch analyzer (CPA). The relationship between membrane patch color and the rotating pressure vessel oxidation test (RPVOT) residual rate was then investigated. The results show that the new estimation method using the CPA and dry TOST is able to monitor the decrease of the RPVOT residual rate from the early stages of oxidative deterioration.

Performance Change of Quench Oils Due to Heat and Oxidative Deterioration

Quench oils are used according to needed qualities such as quench hardness, distortion, and appearance. However properties and performance of quench oils may change due to heat and oxidative deterioration. In addition, the properties and performance changes due to heat and oxidative deterioration also differ depending on the types of base oil and additives used in the formulation of the quench oil. In order to use quench oils for a long period, it is necessary to grasp the properties and performance changes within a quench oil due to heat and oxidative deterioration.In this study, we investigated how heat and oxidative deterioration changes of dark and transparent quench oils. We accelerated the heat and oxidation deterioration testing to determine the performance change of the quench oils and investigate if there is a correlation with the deterioration tendency of quench oils in a laboratory setting versus actual quench furnace usage In conclusion, in the transparent type, the brightness is better compared to the dark type of quench oil. While the cooling performance in transparent oils decrease because the vapor blanket stage length is extended. For dark oils the brightness level is less than the transparent type of oil. However, the stability of the cooling performance is high because the vapor blanket stage length is hardly changed.

Towards Greener Preservation of Edible Oils: A Mini-review

Edible oils like sunflower oil, rapeseed oil, soybean oil, cotton seed oil and olive oil are necessary components in human diet and are extensively utilized in the food trade. Safe storage of edible oils has perpetually been a haul within the food industry since the oils can easily endure oxidative deterioration. Studies specializing on polyphenols as a supply of natural antioxidants of plant origin to delay oxidative deterioration of food products have increased worldwide. Both natural and synthetic antioxidants are widely used in protecting oils against oxidative deterioration. Natural antioxidants are greener preservatives because they are known to be safer than their synthetic counterparts. Currently there is an increased interest in sources of natural antioxidants to enrich oils towards shelf life enhancement. This review highlights some research works in which natural antioxidants from plant materials have been used to preserve edible oils. Most of the natural compounds extracted from medicinal plants were found to be able to preserve edible oils against oxidative deterioration. The potential of most of the natural antioxidants from plant materials to preserve edible oils was found to be comparable to that of synthetic antioxidants in all the reviewed researches. Use of natural antioxidants from plant materials for preservation of edible oils is a promising approach that can be adopted by edible oil manufacturers.

EFFECT OF FRYING TEMPERATURE/FRYING CYCLES ON trans-FATS AND OXIDATIVE STABILITY OF GROUNDNUT OIL - CARDIAC RISK FACTORS

Objective: Frying process leads to oxidative deterioration and generation of trans fatty acids (TFAs) in fats/oils resulting in elevated cardiac risk. The objective of this study was to assess the effect of frying temperatures and the number of frying cycles on TFA and primary/secondary oxidative indices of groundnut oil used for preparing French fries.Methods: TFA (by gas chromatography) and other chemical parameters (by American Oil Chemists’ Society official methods) were estimated at varying temperatures (160°C, 180°C, 200°C, 220°C and 230°C) and frying cycles (1st, 4th, 8th 16th and 32nd).Results: With soaring frying temperatures and progressive frying cycles, mean cis-unsaturated fatty acids decreased while mean saturated fatty acids and TFA increased. Temperature variation indicated increase in mean TFA from 0.13±0.02 g/100 g (160°C; 32nd cycle) to 1.88±0.04 g/100g (230°C;32nd cycle) (p<0.05). With successive frying cycles, TFA increased from 0.10±0.01 g/100 g (1st cycle) to 0.13±0.02 g/100 g (32nd cycle) when oil was heated to 160°C; and 1.16±0.02 g/100 g (1st cycle) to 1.88±0.04 g/100 g (32nd cycle) when oil reached 230°C. Acid value, p-anisidine value and total oxidation value demonstrated a significant increase at varying frying temperatures across the frying cycles (p<0.05); however, peroxide value (PV) indicated an inconsistent trend.Conclusion: TFA and oxidative parameters increased with elevating frying temperatures and progressive frying cycles; however, PV demonstrated inconsistency. Food safety agencies need to formulate policies, stringent food laws and impose necessary regulations to curb oil abuse during frying. There is a dire need to raise consumer awareness regarding deleterious health effects of TFA and oxidative deterioration of edible oils.

EFFECT OF FRYING TEMPERATURE/FRYING CYCLES ON trans-FATS AND OXIDATIVE STABILITY OF GROUNDNUT OIL - CARDIAC RISK FACTORS

Objective: Frying process leads to oxidative deterioration and generation of trans fatty acids (TFAs) in fats/oils resulting in elevated cardiac risk. The objective of this study was to assess the effect of frying temperatures and the number of frying cycles on TFA and primary/secondary oxidative indices of groundnut oil used for preparing French fries.Methods: TFA (by gas chromatography) and other chemical parameters (by American Oil Chemists’ Society official methods) were estimated at varying temperatures (160°C, 180°C, 200°C, 220°C and 230°C) and frying cycles (1st, 4th, 8th 16th and 32nd).Results: With soaring frying temperatures and progressive frying cycles, mean cis-unsaturated fatty acids decreased while mean saturated fatty acids and TFA increased. Temperature variation indicated increase in mean TFA from 0.13±0.02 g/100 g (160°C; 32nd cycle) to 1.88±0.04 g/100g (230°C;32nd cycle) (p<0.05). With successive frying cycles, TFA increased from 0.10±0.01 g/100 g (1st cycle) to 0.13±0.02 g/100 g (32nd cycle) when oil was heated to 160°C; and 1.16±0.02 g/100 g (1st cycle) to 1.88±0.04 g/100 g (32nd cycle) when oil reached 230°C. Acid value, p-anisidine value and total oxidation value demonstrated a significant increase at varying frying temperatures across the frying cycles (p<0.05); however, peroxide value (PV) indicated an inconsistent trend.Conclusion: TFA and oxidative parameters increased with elevating frying temperatures and progressive frying cycles; however, PV demonstrated inconsistency. Food safety agencies need to formulate policies, stringent food laws and impose necessary regulations to curb oil abuse during frying. There is a dire need to raise consumer awareness regarding deleterious health effects of TFA and oxidative deterioration of edible oils.