Application of edible coatings in minimally processed sweet potatoes (Ipomoea batatas L.) to prevent enzymatic browning

To control browning phenomenon, an edible coating of cassava starch along with ascorbic acid (AA) (combined treatment) was applied to minimally processed sweet potatoes var cv. ‘Blanca Correntina’. The samples were stored at 4 °C for 16 days, and the activities of polyphenol oxidase, peroxidase and phenylalanine ammonia lyase were studied; also, surface colour, antioxidant capacity, ascorbic acid, chlorogenic acid content were evaluated. The combined treatment showed a beneficial impact on the quality of the product, avoiding browning when compared with untreated samples and individual treatments (coating without AA or immersion in AA solution). The improvements were evidenced by the absence of changes in hue, minor changes in a* parameter and a major inhibitory effect of AA on the activity of the three enzymes. Ascorbic acid content and antioxidant capacity increased (P < 0.05). The combined treatment not only was effective in preventing enzymatic browning but also retained freshness and improved nutritional value.     

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.     

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%。     

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.     

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.     

Analysis of sphingolipids in potatoes (Solanum tuberosum L.) and sweet potatoes (Ipomoea batatas (L.) Lam.) by reversed phase high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS)

Ceramides and glucocerebrosides of potatoes (Solanum tuberosum L.) and sweet potatoes (Ipomoea batatas (L.) Lam.) were analyzed using RP-HPLC-ESI-MS/MS. Ceramides and glucocerebrosides containing the three different long-chain bases 4,8-sphingadienine (d18:2(delta4,delta8)), 4-hydroxy-8-sphingenine (t18:1(delta8)), and 8-sphingenine (d18:1(delta8)) acylated to saturated and unsaturated hydroxy- and nonhydroxy fatty acids with 16-26 carbon atoms were detected. For ceramides and glucocerebrosides 4,8-sphingadienine (d18:2(delta4,delta8)) was found as the major long-chain base, with lesser amounts of 4-hydroxy-8-sphingenine (t18:1(delta8)) and 8-sphingenine (d18:1(delta8)). 2-(Alpha-)hydroxypalmitic acid (C16:0h) was the major fatty acid, which was found to be acylated to the long-chain bases. For quantification of these compounds, an RP-HPLC-ESI-MS/MS method with an "echo-peak"-technique simulating internal standard injection was developed. The analyzed samples of potatoes and sweet potatoes showed amounts of approximately 0.1-8 microg/kg single ceramides and amounts up to 500 microg/kg glucocerebrosides, with C16:0h-glucosyl-4,8-sphingadienine as the major component.     

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.     

超声-微波协同萃取善薇果中黄酮类物质的研究

研究了超声-微波协同萃取新疆蔷薇果中黄酮类物质的工艺条件.结果表明:最佳工艺务件为用65%乙醇在70℃功率为200W的条件下萃取20min,料液比为1:10,总黄酮提取率为88.72mg/g.     

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.     

响应曲面法优化超声—微波协同提取百合渣中总皂苷工艺的研究

以宜兴百合淀粉生产过程中产生的副产物百合渣为原料,采用超声-微波协同提取工艺提取其中的总皂苷,通过乙醇浓度、液料比、微波功率、提取时间各单因素实验确定各因素对总皂苷得率的影响。在单因素实验的基础上,根据Box-Behnken实验原理,采用了四因素三水平的响应面分析法,以总皂苷的得率作为响应值,根据所得实验结果进行回归分析,优选出提取的最佳工艺为:乙醇浓度77%,液料比11∶1（mL/g）,微波功率503W,提取时间139s,在此最佳条件下,测得总皂苷的得率为6.59‰。该工艺运用了超声与微波的协同效应,集取了超声与微波二者优势,具有提取时间短、效率高的优点。      

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,...     

甘薯多酚粗提液的抗氧化活性研究

采用抗坏血酸和没食子酸作为对照,全面测定了甘薯多酚粗提液对超氧阴离子自由基、羟基自由基、DPPH自由基的清除率、还原能力、抗脂质过氧化活性以及对食用油脂的抗氧化性的影响,结果表明甘薯多酚粗提液具有较强的综合抗氧化能力,是一种有开发价值的天然抗氧化剂。     

Optimisation of pectin extraction from sweet potato (Ipomoea batatas,Convolvulaceae) residues with disodium phosphate solution by response surface method

Disodium phosphate solution was used for extracting pectin from sweet potato residues, and response surface methodology was adopted to optimise the effects of extraction parameters on the pectin yield (%, w/w). The independent variables were liquid/solid ratio, extraction time (h), extraction temperature (°C) and solution pH. The optimal conditions were determined, and 3‐D response surface plot was plotted from the mathematical models. The results indicated that all four factors significantly affected the pectin yield in the following order: solution pH > extraction time > extraction temperature > liquid/solid ratio. The selected optimal extraction conditions were liquid/solid ratio 20:1, extraction time 3.3 h, extraction temperature 66 °C and solution pH 7.9. These conditions yielded about 10.24% of pectin vs. 10.27% for the predicted value. The degree of esterification and gel strength of extracted pectin with disodium phosphate solution in the optimised condition were 11.2% and 115.6 g, respectively.     

Chemical Optimization of Protein Extraction from Sweet Potato (Ipomoea batatas) Peel

Abstract: Proteins isolated from sweet potatoes (Ipomoea batatas) have been shown to possess antidiabetic, antioxidant, and antiproliferative properties. The objective of this study was to chemically optimize a process for extracting proteins from sweet potato peel. The extraction procedure involved mixing peel with saline solvent to dissolve proteins and then precipitating with CaCl₂. Quadratic and segmented models were used to determine the optimum NaCl concentration and peel to solvent ratio to maximize protein solubility while minimizing solvent usage. A segmented model was also used to optimize the concentration of CaCl₂ used for precipitation. The highest yield was obtained by mixing blanched peelings with 59.7 mL of 0.025 mM NaCl per g peel and then precipitating with 6.8 mM CaCl₂. The results of this study show that potentially valuable proteins can be extracted from peel generated during processing of sweet potatoes and industrial costs can be minimized by using these optimum conditions. Practical Application: Potentially valuable proteins can be extracted from sweet potato peel, a waste product of sweet potato processing.     

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.     

Sweetpotato (Ipomoea batatas L.) Leaf: Its Potential Effect on Human Health and Nutrition

Previous experiments revealed that sweetpotato leaves contain a high content of polyphenolics, namely anthocyanins and phenolic acids, compared with the major commercial vegetables. Sweetpotato leaves contain at least 15 biologically active anthocyanins that have significant medicinal value for certain human diseases and may also be used as natural food colorants. The anthocyanins were acylated cyanidin and peonidin type. The phenolic acids were composed of caffeic acid (CA) and 5 kinds of caffeoylquinic acid derivatives, 3‐mono‐O‐caffeoylquinic acid (chlorogenic acid, ChA), 3,4‐di‐O‐caffeoylquinic acid (3,4‐diCQA), 3,5‐di‐O‐caffeoylquinic acid (3,5‐diCQA), 4,5‐di‐O‐caffeoylquinic acid (4,5‐diCQA), and 3,4,5‐tri‐O‐caffeoylquinic acid (3,4,5‐triCQA). These polyphenolics showed various kinds of physiological functions, radical scavenging activity, antimutagenic activity, anticancer, antidiabetes, and antibacterial activity in vitro or in vivo, which may be helpful for maintaining and promoting human health. The physiological function of caffeoylquinic acid (CQA) derivatives with the plural caffeoyl group is more effective than with a monocaffeoyl one. This review describes the nutritional composition and physiological functions of sweetpotato leaves when used as a vegetable, and as a resource for products with these functions.