Hongnan Sun

Optimisation of aqueous two-phase extraction of anthocyanins from purple sweet potatoes by response surface methodology

Aqueous two-phase extraction (ATPE) method was investigated for extraction of anthocyanins from purple sweet potatoes using response surface methodology (RSM). Results showed that the optimal conditions for anthocyanin extraction were that, 45:1 (mL/g) liquid-solid ratio, 25% (W/W) ethanol, 22% (W/W) concentration of ammonium sulphate and pH3.3; the anthocyanin yield and partition coefficient under the optimal conditions were 90.02% and 19.62, respectively. The result of HPLC-ESI-MS analysis revealed eight kinds of compounds, and the major anthocyanins as cyanidi-caffeoy-fumaroy-sophoroside-3-O-glucoside, peonidin-caffeoyl-hydroxybenzoyl-3-O-glucoside, peonidin-caffeoyl-sophoroside-3-O-glucoside, and peonidin-caffeoyl-fumaroyl-sophorosid-3-O-glucoside. Meanwhile, we found a compound as a dimer of galloyl procyanin. These results suggest that ATPE is efficient in extracting anthocyanins and has the potential to be used in natural anthocyanin extraction industry.

Sweet potato (Ipomoea batatas L.) leaves as nutritional and functional foods

In this study, the nutritional compositions of leaves from 40 sweet potato (Ipomoea batatas L.) cultivars were assessed. The correlations between antioxidant activity and crude protein, crude fat, crude fiber, carbohydrate, and polyphenol contents were determined. The crude protein, crude fiber, crude fat, carbohydrate and ash contents ranged between 16.69-31.08, 9.15-14.26, 2.08-5.28, 42.03-61.36, and 7.39-14.66g/100gdryweight(DW), respectively. According to the index of nutritional quality, sweet potato leaves are good sources of protein, fiber, and minerals, especially K, P, Ca, Mg, Fe, Mn, and Cu. The correlation coefficient between antioxidant activity and total polyphenol content was the highest (0.76032, p<0.0001), indicating that polyphenols are important antioxidants in sweet potato leaves. Sweet potato leaves, which contain several nutrients and bioactive compounds, should be consumed as leafy vegetables in an attempt to reduce malnutrition, especially in developing countries.

Preparative purification of polyphenols from sweet potato (Ipomoea batatas L.) leaves by AB-8 macroporous resins.

In this study, the adsorption properties of AB-8 macroporous resin for sweet potato leaf polyphenols was investigated. The adsorption mechanism was elaborated by the Langmuir and Freundlich equations, and the purification parameters were optimised by adsorption and desorption tests. The constituents and their contents of the purified products were analysed, and the antioxidant activities were determined. The results showed that the optimal processing parameters were as follows: an initial polyphenol concentration of 2.0mg chlorogenic acid equivalent (CAE)/ml, pH 3.0, an ethanol desorption solution concentration of 70% (v/v) and a flow rate for feeding and elution of 1BV/h. The purified products mainly contained eight phenolic constituents and the contents of three di-caffeoylquinic acids were relatively higher than the other constituents. The purified products possessed strong antioxidant activities. In conclusion, purification by AB-8 macroporous resin was highly efficient, economic and environmentally friendly and has a great industrial production potential.

Optimization of extraction efficiency by shear emulsifying assisted enzymatic hydrolysis and functional properties of dietary fiber from deoiled cumin (Cuminum cyminum L.)

This study evaluated the optimal conditions for extracting dietary fiber (DF) from deoiled cumin by shear emulsifying assisted enzymatic hydrolysis (SEAEH) using the response surface methodology. Fat adsorption capacity (FAC), glucose adsorption capacity (GAC), and bile acid retardation index (BRI) were measured to evaluate the functional properties of the extracted DF. The results revealed that the optimal extraction conditions included an enzyme to substrate ratio of 4.5%, a reaction temperature of 57 °C, a pH value of 7.7, and a reaction time of 155 min. Under these conditions, DF extraction efficiency and total dietary fiber content were 95.12% and 84.18%, respectively. The major components of deoiled cumin DF were hemicellulose (37.25%) and cellulose (33.40%). FAC and GAC increased with decreasing DF particle size (51-100 μm), but decreased with DF particle sizes <26 μm; BRI increased with decreasing DF particle size. The results revealed that SEAEH is an effective method for extracting DF. DF with particle size 26-51 μm had improved functional properties.

Purple Sweet Potato (Ipomoea batatas L.) Anthocyanins: Preventive Effect on Acute and Subacute Alcoholic Liver Damage and Dealcoholic Effect

This study aimed to investigate the dealcoholic effect and preventive effect of anthocyanins from purple sweet potato (PSPAs) on acute and subacute alcoholic liver damage (ALD). Seven-week-old male inbred mice were grouped into five groups: control group (without PSPAs and ethanol treatments), model group (with ethanol treatment only), low-dose group (50 mg PSPAs/kg body weight), middle-dose group (125 mg PSPAs/kg body weight), and high-dose group (375 mg PSPAs/kg body weight), and the mice in all groups were administered intragastrically. Biochemical parameters of serum and liver were determined, and the histopathological changes of liver tissue were also analyzed. Results showed that all tested parameters were ameliorated after consumption of PSPAs. Therefore, PSPAs have preventive effect on acute and subacute ALD. It is suggested that PSPAs could be used as a supplementary reagent during prophylactic and curative managements of ALD.

Effects of domestic cooking methods on polyphenols and antioxidant activity of sweet potato leaves.

In this study, effects of boiling, steaming, microwaving, baking, and frying on proximate composition, total and individual polyphenol contents, and antioxidant activity of sweet potato leaves were investigated. An increase of 9.44% in total polyphenol content was observed after steaming, whereas decreases of 30.51, 25.70, and 15.73% were noted after boiling, microwaving, and frying, respectively. Decreases of 63.82 and 32.35% in antioxidant activity were observed after boiling and microwaving, respectively, whereas increases of 81.40, 30.09, and 85.82% in antioxidant activity were observed after steaming, baking, and frying, respectively. Eight phenolic compounds were identified in sweet potato leaves. The correlation analysis between content of individual phenolic compounds and antioxidant activity suggested that antioxidant activity could be mainly attributed to 4,5-di-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 3,4,5-tri-O-caffeoylquinic acid. It was suggested that steaming is a preferred method to maintain polyphenols and antioxidant activity of sweet potato leaves.

Influence of potato flour on dough rheological properties and quality of steamed bread

Abstract It is a novel idea to make steamed bread by adding potato flour into wheat flour considering the production and nutritional factors of potato. In this study, the influence of potato flour (0–35%) on dough rheology and quality of steamed bread were investigated. Potato flour addition significantly influenced the dough rheological properties and steamed bread quality, such as increased water absorption, the maximum gaseous release height, total volume of CO2 and hardness, while decreased dough stability and specific volume of steamed bread. Moreover, correlation analysis suggested that dough height at the maximum development time, dough stability, water absorption and the phase tangent can be used for predicting the technological quality of steamed bread. Potato-wheat steamed bread had higher dietary fibre, ash content and antioxidant activity than those of wheat steamed bread. The estimated glycemic index decreased from 73.63 (0%) to 60.01 (35%). Considering the sensory evaluation, the steamed bread with 20% potato flour is acceptable. In conclusion, adding appropriate quantity of potato flour to wheat flour for steamed bread production will not only maintain the technological quality, but also can improve the nutritional value of the steamed bread.

Ultrasonic Modification of Selected Polysaccharides-Review

This review is a survey on ultrasonic application in selected carbohydrate polymers based upon available research reports. It covers a brief discussion on the fundamentals of ultrasound technology, before delving on the effects of ultrasound on specific polymers; pectin, chitin, starch, carrageenan and guar gum, their modification products and possible applications in food, pharmaceutical, biomedical and packaging sectors. Sonication generally leads to depolymerization and side chain break within molecules resulting into oligosugars. Oligosugars are widely used as prebiotics and specific delivery systems; moreover, nano sized products of sonication can be applied in diverse fields. Presently, ultrasonic is finding application in wider sectors therefore better understanding of the complex physico-chemical changes and mechanism of the action of high-intensity ultrasound and its effect on techno-functional properties of compounds would immensely fortify the application of ultrasonic technology.

Effects of high hydrostatic pressure on emulsifying properties of sweet potato protein in model protein–hydrocolloids system

The effects of high hydrostatic pressure (HHP) on emulsifying properties of sweet potato protein (SPP) in presence of 0.1%, 0.3% and 0.5% (w/v) of guar gum (GG) and glycerol monostearate (GMS) were investigated. Emulsifying stability index (ESI) of the SPP with GG revealed significant increase (P<0.05) in ESI value at 600MPa treatment, while the stability of SPP-GMS emulsions significantly decreased with increase in GMS concentrations and HHP treatments (200-600MPa). HHP treatment considerably reduced the creaming rate for SPP-GG model while such case was not observed for SPP-GMS model. The flow index for SPP-GG emulsion model was found to decrease with increase in HHP treatment and had non-Newtonian behaviour. The SPP-GMS emulsion models with HHP treatments showed comparatively lower viscosities but had more Newtonian flow character.

Influence of different hydrocolloids on dough thermo-mechanical properties and in vitro starch digestibility of gluten-free steamed bread based on potato flour

The effects of hydrocolloids (hydroxypropylmethylcellulose (HPMC), Carboxymethylcellulose (CMC), xanthan gum (XG), and apple pectin (AP)) at different concentrations on dough thermo-mechanical properties and in vitro starch digestibility of gluten-free potato steamed bread were investigated. Results showed that hydrocolloids addition significantly increased the gelatinization temperature (from 52.0 to 64.2°C) and water absorption (from 56.22 to 66.50%) of potato dough. Moreover, hydrocolloids may be interacted with protein and starch, the density of potato protein bands was decreased by hydrocolloids addition, the reason might be that higher molecular weight complexes might be formed between proteins-hydrocolloids or proteins-proteins, thus change the protein solubility. Furthermore, steamed breads with hydrocolloids presented higher specific volume and lower hardness, and the rapidly digestible starch and estimated glycemic index were significantly decreased from 45.51 to 20.64, from 69.54 to 55.17, respectively. In conclusion, HPMC and XG could be used as improvers in the gluten-free potato steamed bread.