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Evaluation of quality characteristics, antioxidant activity, functional groups of sweet potato by-products and their usage in sandwich bread processing
(2026-04-01)
Dung, Nguyen Chi
;
Thuy, Nguyen Minh
;
Giau, Tran Ngoc
;
Van Hao, Hong
;
Van Thanh, Nguyen
A substantial quantity of waste is generated during sweet potato processing, posing environmental and economic challenges. This study aimed to valorize sweet potato by-products (SPB) by drying and milling them into powder and incorporating the material into sandwich bread formulations as a partial replacement for wheat flour at levels of 10–25% (corresponding to formulas B1 to B4) along with control sample B0. The physicochemical, structural, and functional properties of SPB powder were evaluated to determine its suitability as a functional ingredient. The results indicated that SPB powder possesses high nutritional value, with considerable amounts of dietary fiber, bioactive compounds, and strong antioxidant activity. Scanning electron microscopy revealed predominantly oval and polygonal particles with relatively smooth surfaces and intact structures. Fourier-transform infrared spectroscopy confirmed a polysaccharide-rich lignocellulosic composition, including starch, cellulose, hemicellulose, and phenolic compounds. Among the tested formulations, bread containing 15% SPB (B2) was identified as optimal, as it maintained desirable moisture content, loaf volume, and color characteristics while significantly enhancing nutritional quality. Compared with the control, the B2 formulation showed substantial increases in dietary fiber and total polyphenols. These findings highlight the potential of SPB powder as a sustainable, high-fiber functional ingredient for bakery product fortification.
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FUNCTIONAL GROUP IDENTIFICATION USING FTIR AND ANTHOCYANIN PROFILING BY HPLC IN PURPLE SWEET POTATO (IPOMOEA BATATAS L.)
(2026-01-01)
Dung, Nguyen Chi
;
Thuy, Nguyen Minh
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Giau, Tran Ngoc
;
Hao, Hong Van
;
Minh, Vo Quang
Background. Purple sweet potato (PSP) has attracted increasing scientific and industrial interest due to its distinctive purple flesh, which is primarily attributed to anthocyanins. Although PSP is produced in large quantities in Vietnam, comprehensive information on its functional groups and anthocyanin pigment composition remains limited. Therefore, characterization of functional groups and identification of anthocyanin pigments are essential to support both scientific research and industrial applications of this raw material. Materials and methods. PSP tubers were collected from farms in Vinh Long Province, Vietnam. The tubers were washed, peeled, sliced, and steam-blanched at 100°C for 3 min, dried at 50°C for 8 h, and milled into powder. Functional groups were characterized using Fourier transform infrared (FTIR) spectroscopy. Anthocyanins were extracted with acidified methanol and analyzed using high-performance liquid chromatography (HPLC) with external standards for pigment identification and quantification. Results. FTIR analysis revealed 14 characteristic absorption bands in PSP grown in Vietnam within the wavenumber range of 3288.63–418.55 cm⁻¹. These bands corresponded to hydroxyl, C–H/O–H/N–H, aromatic (C=O and C=C), ester C–O–C, glycosidic, and pyran ring functional groups, consistent with structural features typical of anthocyanin compounds. HPLC analysis detected three main anthocyanin pigments with retention times of 7.85, 8.77, and 9.93 min, identified as delphinidin, cyanidin, and peonidin, respectively. Their concentrations were 4.034 µg/g (2.2%), 28.490 µg/g (15.5%), and 151.206 µg/g (82.3%). Conclusion. These results indicate that PSP is a promising source of anthocyanins and has strong potential for use as a functional food with health-promoting properties.
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Characterization of orange-fleshed sweet potato starch nanoparticles produced by acid hydrolysis
(2025-01-01)
Dung, Nguyen Chi
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Giau, Tran Ngoc
;
Hao, Hong Van
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Thanh, Nguyen Van
;
Thuy, Nguyen Minh
Sweet potatoes are abundant in starch and have several applications for this component. Starch can be chemically changed to boost its beneficial properties. The objective of this study is to use common, easily accessible, and reasonably priced organic acids to produce modified starch with a nanoscale size from orange-fleshed sweet potato (OFSP). The characterization of OFSP nanostarch were assessed using hydrolysis with three distinct acids (acetic, citric and lactic acid) at concentrations ranging from 5 to 15 %. It was observed that nanostarch's swelling ability and viscosity decreased but its solubility increased during acid hydrolysis. OFSP nanostarch hydrolyzed with 10 % citric acid had a good recovery efficiency and quality suitable. Some physico-chemical properties of OFSP nanostarch were determined. Scanning electron microscopy and transmission electron microscopy were observed. The size of OFSP nanocrystals is in the range of 900–930 nm. The Fourier transform infrared (FTIR) spectrum of acid-treated starch contained 22 spectral peaks ranging from 3282.84 cm<sup>−1</sup> to 418.55 cm<sup>−1</sup>, which indicated the vibrations of glycosidic bonds, hydroxyl groups, and C[dbnd]O bonds. Differential scanning calorimetry investigation revealed that sweet potato starch nanocrystals gelatinized at temperatures ranging from 65.4 to 89.1 °C. OFSP starch nanocrystals from acid-treated starch samples exhibited peaks at diffraction angles 2θ around 10°, 11°, 15°, 17°, 18°, 20°, and 23°. Producing nanostarch from OFSP starch not only raises the usage value of this raw material in the producing areas, but it also adds to the long-term development of this resource when the resulting products are well and widely used in various domains.
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Nutritional value, antioxidant activity and color properties of white-fleshed sweet potatoes in Vietnam
(2025-01-01)
Dung, Nguyen Chi
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Giau, Tran Ngoc
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Van Hao, Hong
;
Minh, Vo Quang
;
Van Tai, Ngo
Sweet potatoes have been considered an essential food source in the human diet for centuries. The study provides comprehensive knowledge on the physico-chemical properties and antioxidant potential of white-fleshed sweet potato (WFSP), to raise consumer awareness of its positive health effects and encourage its greater use. The study also explores whether the food is acidic or alkaline to enhance its health benefits, through Potential Renal Acid Load (PRAL) score. Phenolic acid components were identified and quantified by Ultra-Performance Liquid Chromatography (UPLC), while the functional groups of these compounds were determined by Fourier transform infrared (FTIR) spectroscopy. The results showed that WFSP contains high levels of minerals, including potassium 79.56 mg/100 g, phosphorus 18.69 mg/100 g, magnesium 9.58 mg/100 g and calcium 7.68 mg/100 g. Resistant starch is also present in WFSP at a relative amount of 1.12 %. The total polyphenol content and total flavonoid content were found to be 1.58 mg GAE/g and 0.69 mg QE/g, respectively and it was a source of antioxidant potential (with IC<inf>50</inf> DPPH and IC<inf>50</inf> ABTS·+ determined as 3.31 mg/mL and 0.38 mg/mL, respectively). WFSP was identified as an alkaline food with a negative value (-0.63). Low-PRAL/alkali-ash diets have been linked to a variety of health benefits, including an improved potassium-to-sodium ratio, less muscle wasting and higher intracellular magnesium concentrations. FTIR analysis showed that the phenolic components in WFSP contained 17 functional groups. UPLC analysis identified the main phenolic acids in WFSP as caffeic acid, coumaric acid and trans-ferulic acid, which are antioxidant compounds that can protect cells from damage.
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