Pectin is a kind of hydrophilic plant gum, by the α-1,4 glycosidic linkage of galacturonic acid and rhamnose, arabinose, galactose and other neutral sugar polymerization, is one of the important food additives. At present, the world's annual demand for pectin nearly 20,000t, according to relevant experts predicted that the demand for pectin in a fairly long period of time will still be l5% annual growth rate. Explore new methods and resources to improve the yield and quality of pectin, not only can provide a theoretical basis for the extensive application of high-quality pectin in the field of food processing.
The extraction methods of pectin mainly include acid hydrolysis, ion exchange resin method, subcritical water extraction ,microbial extraction, microwave extraction, enzyme extraction and ultrasonic extraction, the decoloration methods mainly include activated carbon decoloration, hydrogen peroxide decoloration and macroporous resin decoloration, the precipitation methods mainly include alcohol precipitation and saline precipitation, and the drying methods mainly include ambient drying, vacuum drying, freeze drying and spray drying.
How to choose the appropriate extraction and decolorization and drying methods need to be combined with the cost and materials for comprehensive consideration. Below we use ultrasonic extraction equipment to extract pectin to explore the different sources of pectin on the optimal value of ultrasonic power what is the difference? What are the differences?
There are indeed differences in the optimal value of ultrasonic power for different pectin sources, and these differences are mainly influenced by the plant origin of the pectin, the cellular structure, the chemical composition of the pectin, and the molecular structure of the pectin, among other factors. Here are some specific examples:
1. Citrus pectin: In one study, three variables (ultrasonic power, extraction time and pH) were optimized by a Box-Behnken design and the optimal conditions obtained were 150 W of ultrasonic power. In another study, the optimal conditions for ultrasound-assisted extraction of pectin from citrus peel were ultrasound power density of 0.41 W/mL, temperature of 67 °C, and extraction time of 56 min, at which time the pectin release rate was 27.34%.
2. Grapefruit peel pectin: In comparing the ultrasound-assisted extraction of pectin from grapefruit and sweet lemon peels, the optimized conditions for UAE obtained by response surface methodology (RSM) were: ultrasound time = 9.38 min, power = 44.01%, and liquid-to-solid (L:S) ratio of 46.8:1, and these levels led to the highest pectin yield from grapefruit peels (26.35%) and a high galacturonic acid content ( 69.11%; GalA).
3. Apple pomace pectin: In the optimization of the ultrasonic-assisted extraction process of pectin from apple pomace, the process conditions for obtaining the optimum yield of pectin from apple pomace were: material-liquid ratio of 1:20 (g:mL), pH 2.4, extraction temperature of 86 °C, and ultrasonic power of 425 W.
These studies showed that the optimal value of ultrasonic power not only depends on the source of pectin, but is also affected by other factors such as extraction time and temperature. Therefore, in practical applications, experiments are needed to determine the optimal ultrasonic power for a specific pectin source.