The extraction procedure of polyphenols from sweet potato leaves is given in Figure 11.3.23:
Figure 11.3.23 Extraction procedure of polyphenols from sweet potato leaves.
Preparative Purification of Sweet Potato Leaf Polyphenols Crude polyphenol solutions are dynamically adsorbed and desorbed by an AB-8 macroporous resin column. The eluted solution is collected and concentrated in a rotary evaporator at 45 °C to remove the ethanol and then freeze-dried.
The possible products of sweet potato stem and leaf polyphenols may include bread, cakes, desserts, beverages, ham, facial masks, cosmetics, medicine, standard substances, etc.
11.3.11 Sweet Potato Leaf Powder
China is one of the largest sweet potato producing countries, and has abundant resources of sweet potato leaves. Nevertheless, most of the sweet potato leaves are discarded or used as animal feedstuffs, and research on biological active ingredients in sweet potato leaves are limited. Recently, a series of products towards sweet potato leaves have been developed, such as quick-frozen, dried, healthcare beverage, concentrated protein and canned products, but these products are still in the promotion stage. Moreover, the processing, storage and transportation conditions of the above-described products are limited, which can easily cause the loss of processing materials and the deterioration of nutrients, so that these products are not suitable for production by small- and medium-sized enterprises. Therefore, it is extremely urgent to develop the sweet potato leaf processing products for the processing, storage and transportation in small- and medium-sized enterprises with high nutrients, strong healthcare functions, good taste and flavor, and wide application.
Sweet potato leaf powder is prepared by using fresh sweet potato leaves as the raw material, which are then cleaned, dried and finely ground. In this way, the product retains the original color of the sweet potato leaves, without adding any sugar, preservatives or other food additives. It is rich in various nutrients and functional components, such as proteins, polyphenols, dietary fiber, fat and minerals, which can make up for insufficient intake of vegetable nutrients in daily life. The sweet potato leaf powder has an unbelievably wide range of applications, which can be added to cakes, bread, ice cream, beverages, noodles, dumplings, agar jelly, and so on. The possible products of sweet potato powder may include cakes, desserts, ice cream, beverages, noodles, steamed bread, dumplings, porridge, agar jelly, etc.
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