Properties Of Sweet Potato Flour Research Articles

Effects of annealing temperature and time on the structural and physicochemical properties of sweet potato flour hydrogels.

The physicochemical properties of sweet potato flour (SPF) can be modified by annealing. Native SPF was annealed in deionized water at a flour-to-water ratio of 1:3 (w/v) and temperatures of 50, 55, 60, or 65°C for either 12 or 24h. Annealed SPF maintained the A-type crystalline region and displayed increased relative crystallinity, increased pasting temperature, and decreased breakdown. SPF gels showed enhanced hardness together with better springiness when SPF was annealed at low temperature/long time or high temperature/short time. Annealed SPF hydrogel sheets contained larger, more uniform, and smoother pores than native ones. Noticeably, hydrogel sheets made of SPF annealed at 50°C for 24h exhibited advanced fracture strain from 93% to 176%. Overall, this work showed that annealing could modulate the characteristics of SPR hydrogels, which may widen the extent of applications in food industries. However, the annealing conditions need to be optimized.

The benefits of fermentation in improving the pasting properties of composite sweet potato flour and its application in composite white salted noodles

Fermentation treatments change the pasting properties of sweet potato flour, which may improve its utilization in composite flour. This research was carried out to evaluate the pasting properties of composite fermented sweet potato flour and the quality of composite salted noodles using those composite flour. Sweet potato slices were fermented using five different starters (spontaneous, Lactobacillus plantarum, Leuconostoc mesenteroides, a mix of Lactobacillus plantarum and Leuconostoc mesenteroides, and a mix of Lactobacillus plantarum, Leuconostoc mesenteroides, and Saccharomyces cerevisiae), and processed into flour. Native sweet potato flour without fermentation was also prepared as a control. A total of six sweet potato flour (SPF) were then used to substitute 50% of the wheat flour in composite white salted noodles. Then, the pasting properties of the composite flour and the quality of the noodles were evaluated. Results proved that composite fermented SPF had higher pasting properties (peak and final viscosity, break down, and set back value) than those of composite non-fermented SPF. The substitution for fermented SPF in composite white salted noodles decreased cooking loss, cooking time, solid loss, soluble loss, swelling index, adhesiveness, and water absorption, while cohesiveness, elasticity, elongation, and colour brightness increased significantly. Therefore, the incorporation of fermented SPF enhanced the quality of composite white salted noodles.

Effects of fatty acid‐blending heat‐moisture treatment on the physicochemical and in vitro digestion properties of sweet potato flour

SummaryIn this paper, the effects of fatty acid‐blending heat‐moisture treatment (FA‐HMT) on the physicochemical and in vitro digestion properties of sweet potato flour (SPF) were studied based on the study on the physical modification of SPF by HMT. The results showed that the addition of linoleic acid (LOA)/Palmitic acid (PA) damaged the double helix structure of SPF, and reduced the long‐range order, relative crystallinity, anti‐aging, anti‐shearing properties and slow digestible starch (SDS) content of SPF. However, the FA‐HMT promoted the increase of RS5 (starch‐lipid complex) content in SPF, which had a certain positive effect on improving the intestinal environment. The results showed that when the addition ratio of LOA was 2%, the SDS content of SPF decreased slightly, and the SPF had better anti‐aging, anti‐shearing properties and higher RS5 content.

Effect of pretreatments and temperature on chemical properties of sweet potato flour

In this study slices of sweet potato were pretreated with different pretreatments such as; 0.1% w/v potassium metabisulfite (KMS), 1% w/v calcium chloride (CaCl2) and blanching at 80 °C for 5 min. Pretreated sweet potato slices were dried in a mechanical tray dryer at 50, 55, 60 and 65°C simultaneously at constant drying air velocity of 2 m/s in drying chamber. The dried samples were cooled at normal room temperature and grind. After grinding the chemical properties like protein, starch, total sugar, total soluble solids, ash, fiber and colour were studied. Protein temperature. Starch content was found maximum for KMS pretreated sample and decreases with increase in drying content was found maximum for control sample at 60 °C followed by CaCl2, KMS and hot water blanching. Total sugar content was found maximum for CaCl2 pretreated sample at 60 °C. Total soluble solids (TSS) was found increases with increase in drying temperature and found maximum for CaCl2 pretreated sample at 65°C, Ash content was found maximum for CaCl2 pretreated sample and decreases with increase in drying temperature. Fiber content was ranged from 0.10 to 0.18 per cent.

Comparative studies of the physicochemical and functional properties of sweet potato (Ipomoea batatas L.) flour

This study aimed to determine the proximate compositions and functional properties of sweet potato flour from different varieties cultivated in Sabah, Malaysia, namely Jepun, Kairot and Kaladi. The results showed that the moisture content of all flour samples was below 14%. The fat and protein content of Jepun sweet potato variety were significantly different (p<0.05) as compared with Kairot and Kaladi sweet potato varieties. The ash and dietary fibre content of Kairot sweet potato flour were higher (p<0.05) compared to Jepun and Kaladi flours. In addition, Kaladi sweet potato had the highest carbohydrate content (82%). There were significant differences (p<0.05) in the values of L*, a* and b* for all sweet potato flours. The Jepun sweet potato flour had the highest foaming capacity, water absorption capacity, oil absorption capacity, swelling power and viscosity. Rapid Visco analyser revealed that significant differences were observed for pasting parameters such as peak viscosity, trough viscosity, breakdown viscosity, final viscosity and setback viscosity. The gelatinisation properties showed that Kairot sweet potato flour had the highest onset temperature, conclusion temperature and enthalpy while Kaladi sweet potato flour had the highest peak temperature.

The Studies on Physico-chemical, Mineral, and Sensory properties of Sweet Potato Flour A studies on phsico-chemical, functional and sensory properties of yellow flesh sweet potato flour

The physio-chemical, mineral, and sensory properties of sweet potato flour were studied. Sweet potato tubers were peeled, washed, diced into 1.5 and 10.0 mm thickness, blanched for 2 and 7 mins. Blanched and un-blanched samples were dried at 70 oC, milled, and packaged. The proximate composition, functional and nutritional properties as well as the sensory acceptability of the reconstituted product were determined.  Results have shown that pH values ranged from 5.7-5.8, bulk density increased to 28% relative to the blanching time. Water absorption and oil absorption capacities were reduced with an increase in blanching time. Swelling capacity increased relatively to temperature but reduces as blanching time increased. The effect of blanching time on mineral content was insignificant, while flour of 10.0 mm samples thickness had higher values. The pasting temperature and peak viscosity range between 78.19-88.33 oC and 11.95-382.31 RUV, respectively. However, peak, trough, breakdown, setback, and final viscosities all reduced as blanching time increased and the 1.5 mm samples had higher values than the 10 mm samples. As blanching time and sample thickness increased the sensory attributes of reconstituted flour studied obtained lower scores. The color got darker and the un-blanched samples A and B were the most preferred. The sensory analysis of the reconstituted flour samples indicated that the un-blanched samples A and B were the most preferred samples. Conclusively, blanching for a long period is not suitable for the processing of sweet potato flour. Keyword: Sweet potatoes, physico-chemical properties, quality parameters, un-blanched, blanched, sweet potato flour.

Natural spontaneous fermentation effects on the properties of sweet potato flour and the resulting wet noodles

Sweet potato flour has several weaknesses that hinder its application in noodle making processes. The aim of this study was to improve sweet potato flour by using starch modification through fermentation and to find a wheat flour substitute when making wet noodles. The fermentation took place spontaneously naturally, and through the addition of Lactobacillus plantarum. The modification consisted of M1 = without modification, native; M2 = 4 days natural fermentation of 0.5 cm thickness sweet potato; M3 = 4 days natural fermentation of 1 cm thickness sweet potato; M4 = 2 days L. plantarum fermentation of 0.5 cm thickness sweet potato; and M5 = 2 days L. plantarum fermentation of 1 cm thickness sweet potato. The concentration of sweet potato flour (K) as wheat flour substitute for the noodle were K1 = 25%, K2 = 50%, and K3 = 75%. The flour of M2 natural spontaneous fermentation had the highest viscosity at 80°C and 26°C. Moreover, the noodle made from M2 flour at all the different concentrations possessed the highest elasticity. In addition, the M2 flour at 50% concentration resulted as the best interaction treatment for producing noodles with acceptable sensory descriptive values.

Effect of Enzymatic Hydrolysis on Structural, Chemical and Elemental Properties of Sweet Potato Flour

In the present study, the structural, chemical and elemental changes of sweet potato flour after hydrolysis by α-amylase (liquefaction) and a mixture of α-amylase and glucoamylase (saccharification) were investigated. Thin layer chromatography (TLC), high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), fourier-transforms infrared spectroscopy (FTIR) and energy dispersive X-ray fluorescence spectrometry (EDXRF) were used to study the properties of the hydrolyzed sweet potato starch. Efficient hydrolysis was evidenced from both TLC and HPLC that the thermostable α-amylase was able to yield the simple forms of sugar such as glucose, fructose, maltose and maltotriose whereas, only glucose is depolymerized after the combined effect of α-amylase and glucoamylase. SEM analysis of raw, liquefied and saccharified sweet potato root flour (SPRF) showed the various porous starch granules with a high degree of structural changes in saccharified samples in comparison to others, which indicates the active involvement of tested the enzymes. The saccharified SPRF were fermented by Saccharomyces cerevisiae and Zymomonas mobilis separately and the results confirmed that Z. mobilis was able to produce more stretching vibration of –OH than S. cerevisiae, suggesting better production of bioethanol. In addition, the elemental analysis was carried out to evaluate the impact of S. cerevisiae and Z. mobilis with respect to elemental constituents. The results of the elemental analysis showed increase in the concentrations of S, Cl, Ca, Mn, Fe and Zn and decrease in the concentrations of P and K in the fermented residue of S. cerevisiae and Z. mobilis, however more variation was observed in Z. mobilis.

Physicochemical properties of purple sweet potato flour fortified with legumes

The popularity of purple sweet potato continues to increase annually. Natural sweetness, attractive color, and high antioxidant were alleged as the main allurement of its products. Nevertheless, there are some lacks on the nutritional properties of purple sweet potatoes, such as low in protein and lipid. This shortcoming could lead to a serious malnutrition problem if there is no nutritional complement from another source. In this condition, fortification could serve as a strategy that addressed to improve the nutritional value of sweet potato products. As a source of protein and bioactive compounds, legumes are potential to be a carrier on the fortification process. This study was aimed to determine the physicochemical properties of sweet potato flour fortified with legumes. A completely randomized design with four fortification treatment was used, i.e. soybean, mungbean, cowpea, and without fortification as a control treatment. The results showed that among other legumes, soybean is the most effective carrier on fortification of sweet potato flours. Purple sweet potato flours that were fortified with 10% soybean have the highest nutritional properties, specifically protein (8.65%), lipid (3.02%), and amylose (32.09%). Legume fortification would also reduce the carbohydrate fraction and generated darker colors in the sweet potato flours.

Effect of Fermentation on Some Properties of Sweet Potato Flour and its Broken Composite Noodle Strand

Effect of Fermentation on Some Properties of Sweet Potato Flour and its Broken Composite Noodle Strand

Impact of Thermal and Chemical Pretreatments on Physicochemical, Rheological, and Functional Properties of Sweet Potato (Ipomea batatas Lam) Flour

The impact of thermal and chemical pretreatments on the physicochemical, rheological, and functional properties of sweet potato flour was investigated. The chemical pretreatment consisted in dipping peeled sweet potatoes in 1 % (w/v) calcium chloride (CaCl2), while the thermal pretreatment was achieved by blanching them in tap water at 90 °C for 1 min. Composition in flour moisture, protein, fat, non-reducing sugars, and starch was determined using standard methods. Particle size, color, gelatinization, and rheological properties were analyzed. The water absorption index (WAI) and water solubility index (WSI), as well as the swelling capacity (SC) and sorption isotherms, were determined. The reducing sugar content of sweet potato flour was slightly higher in CaCl2-pretreated (SSPCaCl2) samples than that in blanched (SSPB) and control (SSP) samples. However, the lightness of the SSPB sample was lower than that of the SSPCaCl2 and SSP samples. SSPCaCl2 sample had the higher value of enthalpy of gelatinization and elasticity modulus G′. The SC was higher in blanched samples. A slight increase in the constant of water binding energy (C BET) was observed after the CaCl2 treatment and a marked increase for the blanched sample. Owing to the differences induced by blanching and CaCl2 pretreatments, CaCl2-pretreated flour samples are more suitable for bread-making processes and can also be used in food formulations.

Antioxidant Property Enhancement of Sweet Potato Flour under Simulated Gastrointestinal pH

Sweet potato is known to be rich in healthful antioxidants, but the stability of its antioxidant properties under gastrointestinal pH is very much unknown. Hence, this study aimed to evaluate the changes in antioxidant properties (total contents of phenolics and flavonoids as well as antioxidant activity) of sweet potato flour (SPF) under simulated gastrointestinal pH conditions. It was found that the yield of SPF crude phenolic extract increased from 0.29 to 3.22 g/100 g SPF upon subjection to gastrointestinal pH conditions (p < 0.05). Also elevated significantly were the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of SPF (p < 0.05). In summary, the antioxidant properties of SPF were enhanced under gastrointestinal pH conditions, suggesting that SPF might possess a considerable amount of bound phenolic and other antioxidative compounds. The antioxidant properties of SPF are largely influenced by pH and thus might be enhanced during the in vivo digestive process.

Textural and Gelatinization Characteristics of White, Cream, and Orange Fleshed Sweet Potato Tubers (Ipomoea Batatas L.)

Sweet potato is an important food crop having nutritive value in terms of starch, carotein, and minerals. The acceptability and overall quality of the products depend on their textural and rheological attributes. Cooking quality of the tubers could be related to the textural, pasting, and gelatinization properties, which vary depending on the flesh color of the tubers. Also, being a promising ingredient in many of the traditional and industrial products, the physico-chemical and functional properties of sweet potato flour are very much important for their selection for developing various value added products. The textural, gelatinization, and pasting characteristics of white, cream, and orange fleshed sweet potato tubers were analyzed and their thermal softening behavior was modeled by linear regression and fractional conversion techniques. Significant variations were observed in the properties among different varieties (p < 0.05). Kinetics of texture degradation on cooking were explained by first-order and dual-mechanism first-order models and the latter was found to be more suitable. The first three principal components explained about 85% of the total variation in texture profile parameters, gelatinization, and pasting properties. Though there was no similarity in the textural properties of the raw tubers among the varieties of same flesh color group, the quality of the cooked tubers and flours of different varieties in the same group are similar as revealed by the multivariate analysis.

Physicochemical Properties of Sweet Potato Flour and Starch as Affected by Blanching and Processing

AbstractThe effects of blanching on physicochemical properties of flours and starches prepared from two varieties of sweet potatoes (Mun‐Kai and Negro) were studied and compared. The pasting temperature and peak viscosity of starches, respectively, were 74 and 80 °C and 381 and 433 RVU. The pasting temperature (74.0‐94.8 °C) of flours was greater than that of starch, depending on the variety and blanching process. However, the peak viscosity (ca. 103‐120 RVU) of flours was lower than that of the corresponding starches. Partial gelatinization of starch granules was observed as a result of a 1‐min blanching. Composition of starch and flour was found to affect swelling power and solubility. The starch content of starches, flours from unblanched sweet potato and flours from 1‐min blanched sweet potatoes were 97; 66.3 and 74.9; as well as 36.6 and 40.4%, respectively. Amylose content of flours and starches varied from 17.2‐20.8%.