In vitro starch digestion in sweet potato (Ipomoea batatas L.) flours

The kinetics of starch digestion in cryo‐ and hammer‐milled sweet potato flours were investigated to reveal monophasic digestograms that were independent on particle size (80–390 μm), and suitably described (r² > 0.98; P < 0.05) by a modified first‐order model. Milling conditions significantly affected (P < 0.05) the particle size, salivary–gastric‐digested starch and rate of starch digestion as the effective surface areas changed. The reciprocal of the rate of starch digestion (1/K, s) was significantly related to the square of the average particle size (size², cm²), with the reciprocal of the slope (0.9–3.8 × 10^?7 cm² s^?1) revealing diffusion‐controlled digestion. The hammer‐milled flours gave different digestion and functional parameters as frictional heat and glass transition phenomena played different roles in the overall structural changes in the flours. These parameters are discussed with starch digestion parameters in cereals and legumes to understand starch digestion in sweet potato.     

Lactic acid fermentation of anthocyanin-rich sweet potato (Ipomoea batatas L.) into lacto-juice

Sweet potato (SP) is an important root crop grown all over the world and consumed as a vegetable, boiled, baked or often fermented into food and beverages. The grated SP roots [non- boiled and fully boiled (boiled in water at 100 °C for 15 min) were treated with 0.05% of commercial pectinase enzyme (Pectinex, Novoenzyme) in order to extract the juice. The fresh juice was inoculated with Lactobacillus plantarum MTCC 1407 culture at 28 ± 2 °C for 48 h to produce lacto-juice (LJ). The anova analysis of analytical data revealed that there was significant effect of boiling conditions (fully boiled and non-boiled) on pH [ F (1, 4) = 220.5, P  < 0.001), TA [ F (1, 4) = 78.89, P  < 0.01], starch [ F (1, 4) = 26.63, P  < 0.01), total sugar [ F (1, 4) = 61.36, P  < 0.01) and anthocyanin [ F (1, 4) = 32.86, P  < 0.01) but not on reducing sugar [ F (1, 4) = 2.48, P  = 0.19). Sensory evaluation rated the SP LJ acceptable based on texture, taste, aroma, flavour and after taste. LJ prepared from fully boiled roots with 10% cane sugar was most preferred by a consumer's panelist based on Linear Discriminant Analysis. Principal component analyses (PCA) reduced the seven original analytical variables to three independent components (factors), which accounted for 99.9% of the total variations. Similarly, six original sensory variables were reduced to two independent components, which accounted for 65.7% of the total variations.     

紫薯渣果胶提取工艺研究

该试验以紫薯渣为原料研究果胶提取工艺,对预处理后的紫薯渣以果胶含量为考察指标,研究酸提取条件及脱色条件。结果表明,紫薯渣在pH 7.0,温度75 ℃时,α-淀粉酶用量60 U/g原料,酶解时间30 min条件下除去淀粉;酸提取工艺条件为盐酸提取液pH值1.5,温度85 ℃,时间105 min;脱色条件为活性炭用量1%,脱色温度70 ℃,时间30 min;在此条件下制备的果胶含量为3.979%。     

Comparative analysis of phytochemicals and polar metabolites from colored sweet potato (Ipomoea batatas L.) tubers

Food Science and Biotechnology - We determined the phytochemical diversity, including carotenoids, flavonoids, anthocyanins, and phenolic acids, in sweet potatoes (Ipomoea batatas L.) with...     

Degradation kinetics of anthocyanins from purple sweet potato (Ipomoea batatas L.) as affected by ascorbic acid

Storage (4°C and 25°C, 28 days) and thermal (70°C–90°C, 6 h) stabilities of purple sweet potato anthocyanins (PSPAs) with varying concentrations of ascorbic acid (AA) were investigated in a model soft drink medium. For storage stability, the model drink was sterilized at 85°C for 15 min prior to storage. Zero-order kinetics and first-order kinetics were fitted for storage degradation at 4°C and 25°C, respectively. However, all data for thermal degradation fitted first-order kinetics. The temperature dependence on degradation was modeled after the Arrhenius equation. Storage degradation of PSPAs was increased by the presence of AA (40–360 mg/L). Retarded thermal degradation was be achieved by adding 120 mg/L of AA, while accelerated thermal degradation resulted from 360 mg/L of AA. Heat treatment did not markedly change the DPPH radical-scavenging activity of PSPAs.     

Effect of the physical fibrillated sweet potato (Ipomoea batatas) stem on the plant-based patty analogues

Food Science and Biotechnology - In this study, a dietary fiber extracted from sweet potato stems (Ipomoea batatas, PS) was evaluated for its ability to improve the quality of vegetable patty...     

Effects of processing and storage conditions on the stability of sweet potato (Ipomoea batatas L.) leaf flavonoids

The effect of heat, high hydrostatic pressure (HHP) treatment, pH, light, temperature and simulated digestion on sweet potato leaf flavonoids (SPLF) stability was studied. Results showed heat treatment at 75 °C for 90 min or HHP treatment at 600 MPa for 30 min did not cause significant effect on SPLF. Heat treatment at 100 °C for 60 min and 90 min led to decrease in antioxidant activity by 20% and 25%, respectively, while pH 7.0 and 8.0 significantly decreased amount of SPLF by approximately 75%, decreased antioxidant activity by about 30% and 47% separately. Light treated samples recorded a decrease in SPLF by 52% and antioxidant activity by 24%. No significant effect on SPLF was observed for samples stored at −18 °C, 4 °C or room temperature. The retention of flavonoids and antioxidant activity was 45.9 ± 3.6% and 56.2 ± 2.6%, individually in SPLF after simulated digestion.     

Antioxidant content and activity in leaves and petioles of six sweet potato (Ipomoea batatas L.) and antioxidant properties of blanched leaves

Food Science and Biotechnology - This study was conducted to compare antioxidant contents and antioxidative activities in the leaves and petioles of six sweet potato varieties, namely Danjami,...     

Hypolipidemic effect of proteoglycans isolated from sweet potato (Ipomoea batatas LAM) in hyperlipidemia rats

Effects of sweet potato proteoglycans (SPG) in rats fed high lipid diets were investigated. Serum lipid indices for SPG were evaluated. SPG had hypolipidemic effects that were correlated with dosage. There were no significant (p>0.05) differences in hypolipidemic effects between SPG varieties of different molecular weights. SPG-1 (Mw value: 508.3 kDa) significantly (p<0.05) reduced serum total cholesterol (TC), triacylglyceride (TAG), low density lipoprotein cholesterol (LDL-C), and apolipoprotein (Apo) B levels, and the arteriosclerosis index (AI), and induced serum high density lipoprotein cholesterol (HDL-C), ApoA-I, lecithin cholesterol acyltransferase (LCAT), and liver lipoprotein lipase (LPL) activities, compared with controls. The whole blood viscosity and red blood cell (RBC) membrane microviscosity were also decreased. Hypolipidemic effects were mediated via elevation of the serum HDL-C concentration by induction of LACT activity, an increased ApoA-I concentration, and a reduction in the serum lipid concentration due to regulation of LPL activity.     

Modeling respiration rates of Ipomoea batatas (sweet potato) under hermetic storage system

Food Science and Biotechnology - The sweet potato respiration rate versus gas composition was mathematically modeled, as required to design an effective modified atmosphere packaging (MAP) system....     

我国甘薯的分布、特点与资源利用

介绍了甘薯的形态特征、分布、产量及甘薯的品种、特点和资源利用;并归纳列举了12个具体品种的名称、特点及用途.     

甘薯叶过氧化物酶的分离纯化及其部分性质研究

经硫酸铵分级沉淀、DEAE-Sepharose离子交换层析、Sephacryl S-200凝胶过滤层析,从甘薯叶中得到过氧化物酶(POD)电泳纯制品。该酶比活力为91923.14U/mg,纯化倍数为255.69,回收率为1.59%。该酶分子量约为35kD,最适pH值为5.6,最适温度为60℃。该酶在20～50℃、pH4～8内稳定。以不同浓度H2O2为底物在pH7.2和25℃下测得该酶Km值为0.291mol/L。低浓度草酸、尿素、Li+、Na+、K+、Mg2+等对该酶有激活作用;SDS、KSCN、抗坏血酸(AsA)、Mn2+等对该酶有抑制作用;甲醇、乙醇、乙二醇、异丙醇对POD均有一定抑制作用,其抑制作用强弱顺序为异丙醇>乙醇>甲醇>乙二醇。实验表明,该酶稳定性较强。     

Proximate composition and sensory evaluation of anthocyanin‐rich purple sweet potato (Ipomoea batatas L.) wine

Purple sweet potato (PSP) is a special type of sweet potato having high anthocyanin pigment in the root. The starch contents of PSP (root/water homogenised in 1:1 ratio) were enzymatically saccharified [using commercial thermostable enzymes Termamyl^® (0.2%) and Dextrozyme^®GA (1%)] to fermentable sugars, and the filtrate was ameliorated with cane sugar to achieve 20° Brix, for subsequent fermentation into a red wine using 2% yeast (Saccharomyces cerevisiae) as starter culture. The wine had the following proximate compositions: total soluble sugar (TSS), 2.25° Brix; starch, 0.15 g per 100 mL; total sugar, 1.35 g per 100 mL; TA, 1.34 g tartaric acid per 100 mL; phenol, 0.36 g (caffeic acid equivalent) per 100 mL; anthocyanin, 55.09 mg per 100 mL; tannin, 0.64 mg per 100 mL; lactic acid, 1.14 mg per 100 mL; ethanol, 9.33%(v/v); and pH, 3.61. 2, 2‐Diphenyl‐1‐picrylhydrazyl (DPPH) scavenging activity of the wine was 58.95% at a dose of 250 μg mL^?1. Principal component analysis reduced the eleven original analytical and proximate variables (TSS, starch, total sugar, TA, phenol, anthocyanin, tannin, lactic acid, ethanol, pH, DPPH) to four independent components, which accounted for 76.65% variations. Sensory evaluation was carried out by sixteen trained panellists on various attributes such as clarity, colour, viscosity, odour, flavour, spritz and finish. Independent ‘t’ test confirmed that all the sensory attributes of the PSP wine scored closely (within 10% variation) to that of a commercial grape wine. The red wine produced contains essential antioxidants and acceptable sensory qualities.     

Optimization of ultrasound-microwave synergistic extraction of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.)

In this study, efficient ultrasound–microwave-assisted extraction (UMAE) of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.) was investigated. Response surface methodology was used to optimize the extraction conditions: extraction time, ultrasonic power, and microwave power. The prebiotic effect of extracted oligosaccharides on Bifidobacterium adolescentis was also investigated. The results show that the processing conditions of UMAE for optimum the yields of prebiotic oligosaccharides from sweet potatoes (PPOS4 and PPOS5) and corresponding absorbance (OD) are 100 s extraction time, 300 W ultrasonic power, and 200 W microwave power. Under these conditions, the experimental yields of PPOS4 and PPOS5 and the corresponding OD were 1.472%, 5.476%, and 2.966, respectively, which match the predicted values well. Compared with the conventional hot-water extraction (HWE), microwave-assisted extraction (MAE), and ultrasound assisted extraction (UAE) methods, the UMAE procedure exhibited significantly high extraction efficiency (p < 0.05). Comparison of SEM images of tissues of the sweet potatoes after extractions indicate microfractures and disruption of cell walls in the potato tissues. These results confirm that UMAE has great potential and efficiency in the extraction of bioactive substances in the food and medicinal industries.Industrial relevanceUltrasound–microwave-assisted extraction is a new process technology that combines the ultrasonic and microwave methods. It makes full use of the high-energy effect of microwaves and ultrasonic cavitation. And it overcomes the shortcomings of conventional, ultrasonic, and microwave extractions. Fast, efficient extraction using this method can be realized at low temperature under ambient conditions, enhancing competition of industries to be more ecologic, economic and innovative.     

Defensin protein from sweet potato (Ipomoea batatas [L.] Lam 'Tainong 57') storage roots exhibits antioxidant activities in vitro and ex vivo

This study was designed to investigate the antioxidant activities of sweet potato defensin (SPD1) in vitro and ex vivo. Antioxidant status [2,2'-azinobis[3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay], scavenging activity against DPPH (1,1-dipheny-2-picrylhydrazyl) radical method, reducing power method, Fe(2+)-chelating ability, FTC (ferric thiocyanate) method, and protection of calf thymus DNA against hydroxyl radical-induced damage were studied in vitro. The ex vivo experiments revealed that SPD1 could decrease the production of intracellular peroxide in HepG2 cells. Four peptides, namely GFR, GPCSR, CFCTKPC and MCESASSK for testing antioxidative activity, were synthesized according to tryptic hydrolysis simulation. In the TEAC assay CFCTKPC performed the best (13.5±0.3μmol TE/g dw), even better than reduced glutathione (7.3±0.2μmol TE/g dw). In the DPPH radical assay (%), [IC(50) (μM) (the concentration required for scavenging 50% activity)] CFCTKPC again had the highest antioxidant activity (IC(50) is 11.3±3.2μM) even better than reduced glutathione (IC(50) is 74.3±2.4μM). In the lipid peroxidation assay, once again CFCTKPC performed the best, with an IC(50) value of 0.5±0.0μM better than reduced glutathione (1.2±0.1μM). These findings mean that cysteine residue is most important in antioxidant activities. It was suggested that SPD1 might contribute its antioxidant activities against hydroxyl and peroxyl radicals.     

Amylose and amylopectin molecular fractions and chain length distribution of amylopectin in 12 varieties of Ghanaian sweet potato (Ipomoea batatas) flours

Sweet potato (Ipomoea batatas) is a commonly cultivated root crop in tropical and subtropical regions, including Ghana. Different varieties of sweet potato have been bred, in order to expand its utilisation within the food and industrial sector. This study analysed flours made from 12 recently developed Ghanaian sweet potato varieties in terms of their amylose and amylopectin molecular fractions and amylopectin chain length distribution. Starch content of the sweet potato flours ranged from 49 to 77 g/100 g dry matter, with 11 of the varieties containing above 60 g/100 g dry matter. An orange-fleshed variety, Apomuden, had the lowest amount of starch (48.9 g/100 g dry matter), while the cream-fleshed variety Histarch had the highest (77.3 g/100 g dry matter). The flours from the 12 sweet potato varieties had intermediate amounts of amylose, within the range 10–30 g/100 g dry matter, and showed typical molecular distribution according to size-exclusion chromatography (SEC). The fine structures of amylopectin, as revealed by anion-exchange chromatography, contained features common for starches of C-type X-ray pattern, but some structural differences were also observed.     

Effect of photoperiod on flavonoid pathway activity in sweet potato (Ipomoea batatas (L.) Lam.) leaves

Compared with those of major commercial leafy vegetables, leaves of sweet potato have higher contents of flavonoids and phenolic acids, which provide significant health benefits and may be used as natural colourants. We have analysed the expression of key flavonoid biosynthesis genes using RT-PCR and the accumulation of polyphenolic compounds using high-performance liquid chromatography coupled to a photodiode-array detector, during the development of leaves of sweet potato plants growing under either long day or short day photoperiods. A massive induction of flavonoid pathway gene expression, correlating with a dramatic increase in the content of an anthocyanin, catechins, flavonols, hydroxycinnamic acids and hydroxybenzoic acids, was observed during sweet potato leaf exposure to a long day photoperiod. These results provide further support for the protective role of flavonoids and phenolic acids against enhanced light exposure in plants.