Antioxidant effect of persimmon peel extract in the stabilization of sunflower oil during storage and thermal conditions

Dissertation for Master's Degree in Food Science and Industry

Food Technology Orientation

Abstract:

In addition to changing the organoleptic characteristics of food, the oxidation of oils reduces the nutritional value and shelf life of oils and due to the production of undesirable compounds in oil for the health of consumers. It is harmful. To prevent oxidation, there are several methods, one of which is the addition of substances called antioxidants. Today, synthetic antioxidants such as TBHQ, BHT, BHA and gallate esters are used for this purpose, but due to the fact that synthetic antioxidants have adverse effects such as mutagenesis and cancer in the human body, they are gradually removed from the list of consumed antioxidants, so it is necessary to prepare and produce natural antioxidants as substitutes. In this research, first an extract was made from the skin of persimmons and the phenolic and tocopherol compounds in the extract were determined, and then the extract was added in two concentrations of 400 and 800 PPM to the sunflower oil sample without antioxidants, and then the sunflower oil samples formulated with this natural antioxidant under temperature conditions of 30 degrees Celsius during 60 days of storage in terms of oxidative stability by the parameters of peroxide number, oxidation stability index, acid number and color index at storage temperature in Times 0, 15, 30, 45, 60 were compared with sunflower oil sample containing 100 PPM of synthetic antioxidant TBHQ. The results showed that the concentration of 800 PPM persimmon peel extract in stabilizing sunflower oil during the storage period is similar to TBHQ and more effective than the concentration of 400 PPM persimmon peel extract, which is due to the higher amounts of phenolic compounds and tocopherols present in the concentration of 800 PPM extract compared to lower concentrations of the extract. In the next step, sunflower oil containing 800 PPM extract with oil sample containing 100 PPM synthetic antioxidant TBHQ were heated under constant temperature conditions of 180 degrees Celsius for 24 hours and at time intervals of 4 hours (0, 4, 8, 12, 16 and 24) in terms of thermal stability parameters (acid number, conjugate number, oxidation stability index, color index, carbonyl number and total amount of compounds) polar) were compared. The results showed that the synthetic antioxidant TBHQ was slightly more effective than persimmon peel extract with a concentration of 800 PPM in terms of oxidative stability. In this way, persimmon skin can be introduced as a good source of natural antioxidants and this effect is due to the tocopherol and phenolic compounds present in it.

Key words: persimmon skin extract, sunflower oil, oxidative stability, antioxidant compounds.

Introduction

1-1- Persimmon

1-1-1- Botany of Persimmon

Persimmon (Diospyros kaki L.) belongs to the Ebenaceae family, which also includes the hardwood ebony native to Sri Lanka and Southeast Asia. There are almost 200 species in the genus Diospyros. Persimmon, which is also called kaki or oriental persimmon, is cultivated mainly for fruit production. Persimmons originate from China but have been cultivated in Japan for a long time. A great variety of fruit-producing plant material has been found in Japan, and fruit forms without gasses have originated in Japan. The fruit has gained economic value especially in China, Korea and Japan. This treasured tree is important because of the color of its beautiful leaves, especially in autumn. Persimmon with the English name persimmon is known for having high amounts of proanthocyanidin (condensed tannin) and this fruit is widely used in China, Japan and Korea. Persimmon proanthocyanidin has various physiological functions, including antioxidant, anti-inflammatory, antimicrobial activity, as well as enzyme inhibition and detoxification effects on snake venom (Ixiu et al., 2012). The flowering time is late spring and early summer and the fruit ripening time is autumn. Persimmon is also called oriental apple in the west, it is a spherical fruit with a very thin skin that varies in color from yellow to orange to deep orange.The diameter of this fruit is between 3 and 8 cm, and except for the core, which is found in some species, all its parts are edible (Mowat, 1990; Tian et al., 2012). There are types of persimmons: persimmons with and without pulp. The astringent taste found in the fruit is a result of the presence of tannin cells in the flesh of the fruit. If the tannin is soluble, the act of chewing and eating the fruit will tear the cells and release the tannin and gas will be felt. Persimmon is used in traditional medicine to treat colds, blood pressure, shortness of breath, chills, frostbite, burns and bleeding (Mowat, 1990; Tian et al., 2012). Recent studies on persimmon pulp and skin have shown that persimmon is an antioxidant, antidiabetic and DNA protector against oxidative damage. Raw persimmon extract contains a complex mixture of vitamins, p-coumaric acid, gallic acid, flavonoids, and condensed tannins (Jang et al., 2009).

Persimmons are rich in fiber, beta-carotene, and vitamin A, and also contain a significant amount of vitamins B1, B2, B3, and C, as well as essential minerals for the body such as calcium, sulfur, iron, It contains phosphorus, magnesium and potassium and also contains antioxidant substances such as tannin, lycopene, pectin, phenol and acid. Persimmon tree leaves contain flavonoids, which have anti-hypertensive, anti-cancer and anti-mutagenic properties (Sun et al., 2011). The seed of the persimmon fruit, which has been pounded and rolled into a round shape, removes kidney and bladder stones without the need for surgery. Persimmon consumption increases antioxidants and controls free radicals (Sun et al., 2011).

1-1-3- Persimmon chemical compounds

Table 1 shows some of the chemical and physical characteristics of gassy and non-gassy persimmon fruits (Plaza et al., 2012). The assessment of physical characteristics is important in order to design tools and machines for harvesting, transporting, storing and processing fresh fruits, as well as the information obtained from the measurement of chemical characteristics in human nutrition.

Titratable acidity is measured in grams of citric acid per 100 grams of fresh tissue, soluble solids are measured in terms of Brix at 20 degrees Celsius, and the amount of dry matter is measured in grams per 100 grams of fresh tissue. Tables 2, 3 and 4 show the amount of sugar, vitamin C and carotenoid substances of the whole persimmon, respectively (Jiordani et al., 2011). The presence of vitamin C in food is important in terms of antioxidant function in addition to the health aspect. The antioxidant and anti-radical properties of carotenoid compounds have also been reported in many studies. According to the results of the researchers, the persimmon species have higher sugar content than the species without gas, but on the other hand, their vitamin C content is lower than the species without gas. value and shelf life of oils and due to the production of undesirable compounds in oil are detrimental to the health of consumers. There are several ways to prevent oxidation, one of which is adding the substances called antioxidants. Today, synthetic antioxidants such as TBHQ, BHT, BHA and gallate esters are used for this purpose, but regarding the adverse effects of synthetic antioxidants such as mutagenic and carcinogenic effects on the human body, they are gradually removed from the list of consumed antioxidants; therefore the production of natural antioxidants as alternatives is essential. In this study first the phenolic compounds and tocopherols of persimmon peel extract have been determined then the extract at 400 and 800 PPM concentration were added to the sunflower oil samples containing any antioxidants.