Physico Chemical, Antioxidant and Pasting Properties of Pre-heated Purple Sweet Potato Flour

Abstract

Purple sweet potatoes contain anthocyanins which could function as a natural food colorant, and an antioxidant.One of the problems in handling the fresh roots is their susceptibility during storage, and to extend their uses, fresh purple sweet potato could be processed into flour. However, during flouring process, the properties of the purple sweet potato may undergo some changes such as partial gelatinization of the starch and discolorization. Therefore, the purpose of this study was to investigate the effect of pre-heating treatment during flouring process on degree of gelatinization, the anthocyanin content, the antioxidant activity and the total phenolic content of heat treated purple sweet potato flour. Other objectives were to observed the changes in the starch properties such as rheological properties, granular appearance of the heat treated-purple sweet potato flour. Pre-heating treatment of purple sweet potato flour was prepared by heating grated purple sweet potato in a single rotary drum cooker at 90°C for 15, 30, 45, 60 and 75 min, followed by drying in a cabinet dryer at 60°C for 8 h. The results showed the longer pre-heating time at 90°C had caused increase in the degree of gelatinization, increase in total phenolic and anthocyanin retention. In addition, differences in gelatinization temperature, maximum viscosity, paste stability and retrogradation, and differences in scanning electron microscope (SEM) of granular appearance were also observed. The overall results indicated that pre-heating treatment can be used for modifying the physical, chemical and rheological properties to suit various applications and preserving functional properties of purple sweet potato flour.

Functional properties of sweet potato flour and its role in product development: a review

“…[40] This may be due to the differences in the native granule architecture and fragility. [53] Their results were in line with Nurdjanah et al [54] who found that the native sweet potato flour contains starch granule which is round, spherical and surrounded by cell wall material (Figure 3). Ndangui et al [3] studied the impact of thermal and chemical pretreatments on physicochemical, rheological, and functional properties of sweet flour and they observed composed of smooth, round, and spherical granules with quite irregular that exhibits dents .…”

“…[53] The granule size is reported to affect some functional properties and physiology function. [37,54] Wide variability in the size and shape of starch granules has been observed (Figures 3 and 4). Scanning electron microscopy has played an important role in increasing understanding of the granular structure of modified flour starches and used to detect structural changes caused by chemical modifications and the most substituted regions in starch granules.…”

“…Similarly, preheating treatment up to 75 min at 90°C of sweet potato before flouring could change the granular characteristic partly and developed a more compact flour (Figure 3). [54] The authors found that preheating have a noticeable effects and that is due to partial gelatinization as a result of preheating. Modification process and heat treatment are among the factors that differ the morphological features of the flours.…”

Pengaruh Suhu Dan Lama Pemanasan Saat Proses Blansing Terhadap Sifat Kimia, Fisikokimia Dan Fisik Tepung Ubi Kayu

“…Tepung ubi jalar ungu yang telah dimodifikasi secara fisik menggunakan panas dilaporkan dapat memperbaiki sifat fungsional, kadar air tepung yang lebih rendah dari pada kadar air tepung control serta dapat mempertahankan warna aslinya 28,29 .…”

Ice Cream Cup Production Using Purple Sweet Potato (Ipomoea batatas L. Poir) as a Substitute Ingredient

“…However, this sweet potato consists of several types, while the most common type is white, yellow, orange and purple-fleshed sweet potato. However, purple sweet potato is still less known than any other types, although the antocyanin content of this type is considered high and becoming a source of natural antioxydant which can be beneficial for our body (Nurdjanah et al, 2017). Antocyanin content of purple sweet potato is relatively high, which is up to 519 mg/100gr of the wet weight.…”