Bioscience Methods 2024, Vol.15, No.6, 275-288 http://bioscipublisher.com/index.php/bm 276 sweet potato varieties, while also exploring the potential of sweet potato by-products in industrial applications to emphasize the importance of innovative processing methods for maximizing value. 2 Overview of Sweet Potato Composition and Properties 2.1 Chemical composition: carbohydrates, proteins, fibers, and antioxidants Sweet potatoes are rich in a variety of bioactive compounds, including carbohydrates, proteins, fibers, and antioxidants. The carbohydrate content, primarily in the form of starch, ranges significantly among different cultivars, with values reported between 31.68% and 69.21% of dry weight (DW). Proteins in sweet potatoes also vary, with an average content of around 5.41 g/100 g DW, but can range from 2.36% to 8.60% DW depending on the cultivar (Kourouma et al., 2019; Zhang et al., 2022). Fibers, both soluble and insoluble, are another important component, contributing to the dietary benefits of sweet potatoes. The fiber content can range from 1.00% to 14.35% DW (Kourouma et al., 2019; Shaari et al., 2021). Antioxidants such as polyphenols, flavonoids, carotenoids, and anthocyanins are abundant in sweet potatoes, with significant variations across different cultivars. For instance, the total polyphenol content can be as high as 9.38 mg GAE per g DW in some cultivars. Carotenoids, particularly β-carotene, are notably high in orange-fleshed varieties, while anthocyanins are more prevalent in purple-fleshed varieties (Kim et al., 2015; Alam, 2021). 2.2 Physicochemical properties affecting processing techniques The physicochemical properties of sweet potatoes, such as moisture content, ash, protein, fat, carbohydrate, and fiber, significantly influence their processing techniques. Moisture content, which ranges from 5.93% to 7.86%, affects the drying and storage stability of sweet potatoes (Shaari et al., 2021). The ash content, indicative of mineral content, varies from 1.95% to 8.11% DW, influencing the nutritional quality and processing behavior (Kourouma et al., 2019). Color parameters (L, a*, b*) are crucial for consumer acceptance and processing quality. For instance, the lightness (L) value ranges from 68.0 to 89.2, which can affect the visual appeal of processed products (Shaari et al., 2021). The viscosity properties, such as peak viscosity (PV), hot paste viscosity (HPV), and cold paste viscosity (CPV), are essential for determining the suitability of sweet potato flours in various food applications. These values range from 90.7 to 318.8 RVU, 77.3 to 208.3 RVU, and 102.6 to 272.7 RVU, respectively (Zhang et al., 2022; Guo, 2024). 2.3 Variability across different cultivars and growing conditions The chemical composition and physicochemical properties of sweet potatoes exhibit significant variability across different cultivars and growing conditions. For example, orange-fleshed sweet potatoes (OFSP) are rich in β-carotene, while white-fleshed sweet potatoes (WFSP) have higher carbohydrate and phenolic contents (Alam, 2021). The genetic diversity among sweet potato varieties leads to differences in nutrient availability and bioactive compound profiles (Shekhar et al., 2015; Zhang et al., 2022). Growing conditions, including soil type, climate, and agricultural practices, also play a crucial role in determining the nutritional and physicochemical properties of sweet potatoes. For instance, Sweet potatoes grown in the hilly and mountainous areas of Jinhua, Zhejiang have brighter colors and higher dry matter content, which is more conducive to processing (Figure 1); sweet potatoes grown in Shanxi province showed higher polyphenol and flavonoid contents compared to other regions (Kourouma et al., 2019). Postharvest storage and processing methods further influence the retention of bioactive compounds and overall quality. For example, home-processing methods such as baking, boiling, and steaming can lead to significant losses in carotenoid content, while also affecting the antioxidant capacity (Kim et al., 2015; Vizzotto et al., 2017). 3 Primary Processing Techniques 3.1 Washing and peeling Washing and peeling are fundamental steps in the processing of sweet potatoes, ensuring the removal of dirt, pesticides, and the outer skin. These steps are crucial for maintaining the quality and safety of the final product.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==