Vegetable oil is oxidized according to the oil extraction method and storage period, and such changes can cause harmful substances, which can cause enormous problems in food hygiene (Song et al., 2003). Rancidity is a phenomenon in which the quality of fat foods is reduced during oil extraction and storage due to various chemical and microbiological factors such as changes in smell and taste and loss of nutritional value (Sanders, 1983). In our previous studies, it has been reported that rancidity occurs in sancho (Zanthoxylum schinifolium Siebold and Zucc) oil (Kim et al., 2012).

Sancho has long been used as an antiseptic, antiinflammatory, diuretic and anti-parasitic agent (Lee, 1996). Sancho oil has traditionally been used for a long time, but extraction methods are not scientifically established and can cause problems with distribution and use.

In order to increase the storage stability of sancho oil, it is advisable to prevent rancidity at the initial stage. It is preferable to add an antioxidant or a blending oil to chemically inhibit rancidity.

A number of synthetic or natural antioxidants have been developed to prevent oxidation of oils and fats. However, because of their effectiveness and economy and stability, there are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and ethylenediaminetetraacetic acid (EDTA) actually used in food, and α-tocopherol is a natural antioxidant (Aluyor and Ori-Jesu 2008).

Blending of vegetable fats/oils with different properties is one of the simplest ways to create new specific products with the desired tissue and oxidative stability (Hashempour- Baltork et al., 2016).

Sancho oil has long sold at very high prices as traditional edible oil. However, sancho oil has been reported to rupture very rapidly according to extraction and storage methods (Kim et al., 2012;Kang et al., 2017). And now there is no proper method to prevent the rancidity of sancho oil. Also, there is no research to prevent rancidity using antioxidants, which is an appropriate method to prevent rancidity of sancho oil. We have devised two methods to prevent rancidity of sancho oil. In other words, the optimal antioxidant was added to sancho oil to prevent rancidity, or to search for edible oil which is resistant to rancidity and to improve storage stability by blending oil.

Therefore, this study was carried out to investigate the antioxidant and blending oil in order to increase the storage stability of sancho oil and to ensure safety to bio materials.

Blending oil also affected acidity by temperature. The vegetable oil is changed in color by high temperature, increase of free fatty acid, increase of peroxide, decrease of unsaturated fatty acid, change of taste aroma, and the like, and the quality of the oil is deteriorated (Lee and Park, 2010).

The oxidation of the oil can be divided into automatic oxidation, photo oxidation and thermal oxidation, and their oxidation mechanisms are somewhat different (Lee, 1990). Among them, the cause of the oxidation of the sancho oil is reported to occur mainly in photo oxidation and heating oxidation (Kim et al., 2012).

In addition to the automatic oxidation, the thermal oxidation occurs when the oil is heated at a high temperature. The formation of carbonyl compounds by pyrolysis of the carbon-carbon bonds of fatty acids, the formation of free fatty acids due to the decomposition of ester bonds, the neutralization reaction, and foam phenomenon occurs (Min and Smouse, 1985).

The light source also affected the acidity of the branding oil (Fig. 2). Light is also part of the external factors that adversely affect the composition and quality characteristics of fats and oils. Light is the initiator and the cause of the reaction leading to the decay of fat and oil. Fats do not absorb visible light spectra, but oxidation can be induced by light absorbed by oil impurities (e.g. pigment, chlorophyll). Oxidation generally involves the production of free radicals (Slavica et al., 2011).

Exposure of corn, coconut, rapeseed, and soybean oil to 500 ft-c fluorescent lamps significantly increased the rate of oxidation of the retention of light (Sattar et al., 1976). Oxidation rates increased under higher wavelength light, and this effect was more pronounced in vegetable oils than in butter fats.

Vegetable oils are easily oxidized and have been tried to treat antioxidants to prevent rancidity. The most commonly used antioxidants are synthetic antioxidants such as BHA and BHT, and natural antioxidants such as tocopherol and propolis (Yoon et al., 1988).

In this study, the differences in the brand equity were also different according to the kinds of antioxidants. Especially, the acid value of propolis treatment was kept lowest.

Tocopherol belongs to the family of phenolic antioxidants and removes free radicals and reacts with singlet oxygen to inhibit lipid auto oxidation. In vegetable oils, alpha tocopherols inhibit the effects of singlet oxygen during sensitive photo-oxidation.

Tocopherol belongs to the family of phenolic antioxidants and removes free radicals and reacts with singlet oxygen to inhibit lipid auto oxidation. In vegetable oils, alpha tocopherols inhibit the effects of singlet oxygen during sensitive photo-oxidation. Frankel (1989) also reported that tocopherol showed antioxidant activity in plant oils, which is consistent with our study.

It was found that vegetable oil added to sancho oil could delay rancidity. First, we searched for plant maintenance which is resistant to rancidity. The acid value of vegetable oil varies depending on the type of vegetable oil, and the acid value of canola oil is the lowest (Fig. 4). The acidity of vegetable oil is known to increase significantly during the induction period (Lee et al., 2007). Grape fruit seed oil were increased from 5.05 to 15.24 to 3.02, olive oil to 1.11, and sesame oil from 1.73 to 4.79 to 2.77, respectively at higher temperatures (Kim, 2017). Also, the acid value of vegetable oil was highest in rice bran oil, followed by corn, rape oil and soybean oil. The acid value for canola oil was 0.071, which is very low compared to corn and virgin olive oil (Kardash and Tur’yan, 2005).

Canola (Brassica napus L) may refer to an edible and commercial vegetable oil (also known as canola oil) produced from the seed of any of several cultivars of rapeseed bred to be low in erucic acid from the Brassicaceae family of plants.

Canola oil having a relatively low amount of saturated fatty acid, a substantial amount of monounsaturated fatty acid, with roughly a 2 : 1 mono- to poly-unsaturated fatty acids ratio (Lin et al., 2013).

The unique composition of fatty acids of rapeseed oil differentiates it from other vegetable oils. Rapeseed oil has a substantial amount (8 ± 12%) of linolenic acid (C18:3) compared to other vegetable oils, such as soybean, sunflower, olive and corn, which contain approximately 8.0%, 0.2%, 0.8% and 0.7% of linolenic acid, respectively (Economou et al., 1991). The high content of unsaturated fatty acids (on average 38%) in rapeseed oil influences its stability (Bandoniene et al., 2000).

Blending oil with canola oil was lower in acid value and less changed than the other vegetable oils (Fig. 5). The lowering of the acid value of the branding oil seems to be due to the different chemical composition of unsaturated fatty acids. This was also demonstrated in the canola oil dilution experiment of Fig. 3.

Mostafa et al. (2013) also reported that when blended with 7 kinds of vegetable oils, linolenic acid increased and linoleic acid decreased when mixed with canola oil. Increase of unsaturated fatty acid will increase antioxidant activity. In other studies, blending of 7 vegetable oils has been reported to improve antioxidant capacity (Neff et al., 1993;Bhatnagar et al., 2009).

Bhatnagar et al. (2009) found that coconut oil and seven mixed plant oils increased the content of monounsaturated fatty acids (8% - 36%), polyunsaturated fatty acids (4% - 35%), total tocopherol (111㎎/㎏ - 582 ㎎/㎏), which showed a DPPH scan scavenging ability of 5% - 33%.

The higher the canola oil, the higher the viscosity. Because the viscosity of canola oil is higher than the viscosity of acid oil, the viscosity increases with blending. The viscosity of the edible oil measured at 24 degrees was reported as 78 for rapeseed, 52 for corn, 54 for soybeans and 56 for coconut (Noureddini et al., 1992).

In this study, branding oil containing 5 - 10% canola oil was more viscous than other edible fats. It was found that the manufacturing process of branding oil was required.

In this study, branding with canola oil was found to be stable against rancidity. Blending oil of canola oil and other edible oils have been reported to improve the stability of nutritional and edible oils. Blending of canola oil and sesame oil and/or rice bran oil enhanced the antifungal effect, total polar compound, carbonyl and acid value, and conjugated diene value on fried potato chips (Farhoosh and Kenari, 2009). Blending oil with canola oil and pumpkin seeds or olive oil enhanced frying potato stability, carbonyl value, acid value, total polar compound and total tocopherol content (Roiaini et al., 2015).

The absolute viscosity of the fluid is an important property required for fluid flow and heat transfer unit operation. This is a very important factor in the manufacture and distribution of oil, such as pumping, flow measurement, heat exchange, sterilization, and refrigeration (Singh and Heldman, 2001).

Chromaticity was changed by diluting canola oil. The difference in the chromaticity of branding is also a characteristic of sancho oil and canola oil. The difference in chromaticity may also vary depending on the state of the seed before extraction and the extraction method. Joo et al. (2017) also reported that the values of L, a, and b changed as sesame oil was mixed with cooking oil such as corn and soybean oil. In this study, the chromaticity difference of the brand is considered to be the difference in color due to the inherent properties of sancho oil and canola oil, as well as the canola oil used for the experiment, which has degumming and deoxidation.

In this study, we confirmed that canola oil and blending oil inhibit rancidity and increase the availability of sancho oil. However, this study did not show the safety results of blending oil. Therefore, further study on safety as well as biological activity of blending oil is desired.