Sweet potato, also known as sweet potato, sweet potato, hawthorn and sweet potato, is an important root-like plant. Sweet potato is more and more popular because of its rich nutritional value and many health care functions. With the continuous development of food science and technology, a variety of sweet potato foods have been developed accordingly. However, during the processing of sweet potato food, due to the browning problem of sweet potato, the color of the processed food is poor and the quality is low, which reduces the actual development and application value of the product. The control of browning during the processing of sweet potato is an urgent problem to be solved in production. Research shows that the browning of sweet potatoes is mainly caused by the polyphenol oxidase they contain. Therefore, it is possible to effectively control the browning of sweet potatoes by inhibiting the activity of polyphenol oxidase. For this reason, the author used sweet potato as raw material, through the selection of commonly used color-protecting agents such as citric acid, ascorbic acid and sodium bisulfite, using their different concentration gradients and color-protecting time for testing and comparison, in order to explore the simple and easy processing of sweet potato The color protection process can effectively control the browning phenomenon of sweet potato processing and improve the quality of sweet potato food.
Through experiments, the three substances of citric acid, ascorbic acid and sodium bisulfite as the color-protecting agents were first investigated. Six concentration gradients of 0.1%, 0.2%, 0.4%, 0.6%, 0.75% and 1.0% were respectively taken. The sliced â€‹â€‹potato chips were soaked in various color protection solutions for 1 hour, and then the relative activity of polyphenol oxidase in the potato pieces was determined by spectrophotometry. The test results show that in the process of sweet potato processing, the concentration of citric acid should be chosen to be about 0.75%, and that of ascorbic acid should be less than 0.6% when it is used to protect color; and when the color is protected with sodium bisulfite, The concentration should be chosen around 0.4%.
Secondly, the influence of color-retention time on browning during sweet potato processing was further explored through experiments. Take three concentrations of citric acid, ascorbic acid and sodium bisulfite as the concentration of 0.5%. Place the sliced â€‹â€‹potato chips in various color protection solutions and soak at room temperature for 0.5 hour, 1 hour, and 1.5 hour respectively. After 2 hours, the relative activity of polyphenol oxidase in the potato chips was determined by spectrophotometry. The results showed that the relative activity of polyphenol oxidase in the potato chips was the lowest when the color protection time of the potato chips was 1 hour in the three color protection solutions, that is, the color protection effect was the best.
At the same time, in order to further improve the control of browning in sweet potato processing, the effect of processing temperature on the activity of polyphenol oxidase in potato chips was also studied. The results showed that the polyphenol oxidase activity gradually increased with the increase of processing temperature. When the ambient temperature is 25Â°C, the polyphenol oxidase activity is relatively low, and the activity is highest at 35Â°C, and the activity begins to decrease when the temperature continues to rise. Therefore, the sweet potato temperature during processing should be less than 25 Â°C.
In order to further optimize the color protection process in sweet potato processing, on the basis of the above-mentioned single-factor tests, four-factor and three-level orthogonal tests were conducted. The result of range analysis showed that the optimum color protection process conditions were compounded. Color protection solution, the ratio of the ingredients into: citric acid 0.8%, sodium bisulfite 0.6%, ascorbic acid 0.4%, color protection time is 1 hour. The color protection time is too short to achieve a color protection effect; the color protection time is too long, the flavor of the product is poor, and the amount of residual sulfur in the product also increases.
An Analytical Balance (often called a "lab balance") is a class of balance designed to measure small mass in the sub-milligram range. The measuring pan of an analytical balance (0.1 mg or better) is inside a transparent enclosure with doors so that dust does not collect and so any air currents in the room do not affect the balance's operation. This enclosure is often called a draft shield. The use of a mechanically vented balance safety enclosure, which has uniquely designed acrylic airfoils, allows a smooth turbulence-free airflow that prevents balance fluctuation and the measure of mass down to 1 Î¼g without fluctuations or loss of product. Also, the sample must be at room temperature to prevent natural convection from forming air currents inside the enclosure from causing an error in reading. Single pan mechanical substitution balance maintains consistent response throughout the useful capacity is achieved by maintaining a constant load on the balance beam, thus the fulcrum, by subtracting mass on the same side of the beam to which the sample is added.
Electronic analytical scales measure the force needed to counter the mass being measured rather than using actual masses. As such they must have calibration adjustments made to compensate for gravitational differences. They use an electromagnet to generate a force to counter the sample being measured and outputs the result by measuring the force needed to achieve balance. Such measurement device is called electromagnetic force restoration sensor.
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