Effect of corn tassel extract Nano encapsulated in basil seed gum and sesame protein isolate on antioxidant, reduction of microbial load, color and sensory properties of meat sausage

Introduction: Nowadays, meat and meat products consumption has increased rapidly due to their high nutritional benefits (Ansarian et al., 2022). Generally, meat is known as an important source of B vitamins and trace elements and greatly contributes to the daily intake of these micronutrients. (Nikmaram et el., 2011). High moisture and nutrient levels make veal meat highly susceptible to microbial spoilage, with aerobic conditions facilitating lipid and protein oxidation. The most important challenge related to meat products is their sensitivity to chemical and microbial spoilage, which can be delayed by using preservatives and increasing the shelf life of meat products. (Oliveira et al., 2022). Oxidative reactions of meat and meat products can cause serious risks to food safety and public health. Antioxidants can effectively retard the oxidation of lipids and proteins. (Ansarian et al., 2022). The antimicrobial activity of corn tassel extract can be attributed to the presence of high phenolic compounds such as Gallic acid, chlorogenic acid, and caffeic acid, and the antimicrobial effect of these compounds is through destroying the cell wall, blocking ion transport pathways, and preventing the synthesis of adenosine triphosphate(ATP). (Elsayed et al., 2022). Over the past few years, many researchers have attempted to prolong the shelf life of foods with a wide range of methods, among which the use of films and coatings prepared from natural products seems highly promising given the health-related problems of synthesized preservatives and the deteriorative effects of thermal. Various organic substances such as carbohydrates, lipids, and proteins can be used to develop edible films and coatings. (Lashkari et al., 2020).
Microencapsulation of plant extracts using biopolymer walls due to increasing the stability of microencapsulated materials by protecting them from environmental, enzymatic, and chemical changes, providing a buffer state against pH changes, dealing with thermal changes and ionic changes, protecting against unpleasant tastes and odors, and the controlled release of micro-coated material can be used as a method to increase the shelf life (Safari et al., 2022). Among these substances, polysaccharides alone and in combination with proteins such as sesame protein isolate are highly regarded for such applications due to possessing appropriate film-forming characteristics. Basil seed is from the basil plant, which is a member of the Labiate family. This plant is originally native to Iran, Turkey, India, and other tropical regions of Asia, Africa, and Europe. Fresh or dried basil leaves are used as a seasoning all over the world and its essential oils are used in pharmaceuticals and flavorings. (Kheshtchin et al., 2022). Therefore, polysaccharides in contact with cellular fluids tend to be quickly surrounded and then decomposed, thus enabling intracellular release, in addition, the presence of hydrophilic groups in their structure, such as hydroxyl, carboxyl, and amino groups, is a useful strategy for improving the bioavailability of core compounds. (Ballesta et al., 2018). Sesame meal and isolated protein are rich in methionine (4-2.5%) and sulfur-containing amino acids (3.8-5.5%). Sesame protein consists of 80% α-globulin and 20% beta-globulin. The functional and physicochemical properties of sesame protein concentrate, and isolate, as well as its use as a food supplement for drinks and bread have been reported so far (Saini et al., 2018). Corn tassels are a waste part of the corn plant, which could be considered a great source of value products such as volatile oils, the flavonol glycosides of quercetin, isorhamnetin, vitamin K and C (Guven et al., 2016), and kaempferol and lipids. Phenolic compounds exhibit a wide range of physiological properties, such as antiallergenic, anti-artherogenic, anti-inflammatory, antimicrobial, antioxidant, antithrombotic, and cardioprotective effects. (Mohsen and Ammar 2009).
Material and methods: According to Iranian national standard number 2303, the ingredients in the sausage included red meat, oil, water and ice, wheat flour, starch and gluten, gums, Sodium polyphosphate, salt and spices, and onion. The raw materials were poured into a special sausage cutter and mixed, the extract of tassel nano coated with basil gum was added individually and in combination with sesame protein isolate with the highest antioxidant and antimicrobial properties and the rest of the water and ice (50%). And the machine was filled. And it was packed in Polyamide coating with food grade. The produced sausage was steamed for 60 minutes at 80°C in the cooking room until the temperature of the center of the product reaches at least 72 °C. Finally, the samples were cooled to 15°C with a cold water shower, and after reaching room temperature, they were kept at 4°C in the refrigerator until the day of the test. The factors examined in this research are physicochemical properties (pH, peroxide, TBA, TVN, release of phenolic compounds, color, organoleptic and microbial. To prepare the nanoemulsion, the extract was added at three levels of 10%, 20%, and 30% to the oil phase containing Tween 80 and sunflower oil, and was stirred for 3 minutes at 50 °C. Then, it was homogenized at different times for 5, 10 and 15 minutes using an Ultra-Turrax and at a temperature of 10°C. Basil seed gum was prepared individually and in combination with sesame protein isolate at a concentration of 30% and in ratios of 1:0 and 1:1 and stirred for 30 minutes on a magnetic stirrer. Two optimal samples with the best size from each extract were used for coating. The coating solutions were slowly added to the prepared emulsion. To further reduce the size, the prepared emulsions were subjected to probe type ultrasound for 3 minutes at room temperature, and in this way the desired nanoemulsion was prepared (Esmailzadeh Kenari et al., 2022).
Results and discussion: The purpose of this research is to investigate the effect of antioxidant, antimicrobial properties and sensory evaluation of tassel extract coated with basil seed gum wall individually and in combination with sesame protein isolate and its effect on the shelf life of meat sausage products during storage. For this purpose, pH, peroxide, Thiobarbituric acid, and microbial tests (total count and mold and yeast) were investigated. The results of the TBA and peroxide test showed that with the passage of storage time, the amount of both factors (peroxide and TBA) in all three samples has an upward trend, and statistical data shows a significant difference between the samples. The highest amount of fat oxidation was observed in the control sample and the rate of oxidation was slower in the Nano coated samples. that this reduction rate in the extract of tassel nano-coated with a combined coating(1.78meqo2/kg) was more than the coating of basil seed gum alone (2.01meqo2/ kg). Also, the TVN factor, which is one of the factors indicating the freshness index of the product, also showed an increasing trend with the passage of time, but its amount at the end of 21 days of storage in the product containing the extract of tassel Nano-coated in the combined coating (14.9) was lower than the permissible limit (25mg/100g), and there is statistically significant difference between samples and storages day. The results of the microbial indicators showed that the addition of Nano-coated tassel extract to the sausage product leads to a decrease in the microbial load of the final product, which was the highest in the use of a combined coating. The lower microbial load in the sausage sample containing nano-coated corn tassel extract can be caused by the phenolic compounds present in the extract which is through the destruction of cell wall, blocking the ion transport pathways and preventing the synthesis of adenosine triphosphate(ATP) and the better concentration of bioactive compounds by sesame protein isolate (Elsayed et al., 2022). Also, corn tassel having low pH(acidic), caused the decrease pH in the samples and in this way it also partially prevents the growth of microorganisms. The general evaluation of the sensory index showed that the sausage sample containing the corn tassel extract coated with composite coating had higher emits than other samples and the best treatment was accepted from the evaluators' point of view.
Conclusion: The results of this study show that the Nano-coated corn tassel extract has good antioxidant and antimicrobial properties. So the highest amount of oxidation is related to the control sample and the lowest is related to the sample containing the extract of tassel nano-coated with a combined coating. Regarding the effect of the extract on the microbial properties of the sausage sample, the trend is according to its effect on oxidation. Also, the data obtained from the sensory evaluation showed that the sausage sample containing the extract of tassel nano-coated with a composite coating had a more favorable sensory quality compared to other samples. The evaluation of the obtained color shows that the redness of the product decreases with the passage of time and that the amount of reduction in the product containing the extract of tassel nano-coated with a combined coating is lower than in other samples.