Preliminary Studies of the Chemical Composition and Sensory Properties of Sweet Potato Starch-Wheat Flour Blend Noodles

Preliminary studies of chemical composition and sensory properties of instant noodles from blends of wheat flour and sweet potato starch were carried out. Sweet potato starch was used to replace wheat flour at 30, 40, 50, 60 and 70%. Proximate, vitamin A, mineral analysis and sensory evaluation were carried out by standard methods. Results showed that the formulated noodles had higher carbohydrate (63.34 – 70.53%), moisture (4.34 – 4.97%) and vitamin A (11.62 – 35.00 mg/100 g) but lower protein (3.36 – 7.89%), fat (16.91 – 25.09%), calcium (0.73 – 0.89%), phosphorus (0.24 – 0.32%), iron (0.10 – 0.27%) and ash content (1.17 – 3.17%) than the commercial noodles from wheat flour. The noodles containing 30% sweet potato starch showed no significant difference (p > 0.05) from commercial noodles (100% wheat flour) in terms of colour, crunchiness, taste and general acceptability, with improved nutrient composition. It is concluded that production and consumption of wheat flour/potato starch blend noodles should be encouraged to increase the calorie and vitamin A intake in the diet, especially for children who are the major consumers of noodles; apart from helping to promote and improve the utilization of sweet potato tubers.     

Effect of hydrothermal treatment of runner bean (Phaseolus coccineus) seeds and starch isolation on starch digestibility

The study investigated the effect of traditional soaking and cooking, storage after cooking and freezing (? 18 °C, 21 days) and autoclaving of two varieties of runner bean on starch digestibility. Results achieved were compared with digestibility of isolated starch subjected to similar treatments. The digestibility of native starch from Nata var. seeds was lower after isolation than in raw flour. This starch was characterized by a higher content of fat and lower values of swelling power (SP) and amylose leaching (AML). After the thermal treatment, a significantly higher content of rapidly digestible starch (RDS) was observed both in seeds and starch. It was accompanied by reduced contents of resistant starch (RS) and slowly digestible starch (SDS). In flours from cooked seeds, the content of RDS was observed to be higher than in flours from autoclaved seeds, despite similar changes in contents of other constituents (ash and protein). It was probably due to better starch gelatinization owing to the long-lasting soaking of seeds. This resulted in a greater decrease of amylose content of starch compared to the other flours. Differences in SP, AML and thermal properties between starches isolated from two bean varieties had no influence on their digestibility after cooking. The storage of starch pastes at a temperature of ? 18 °C, unlike that of seeds, resulted in a significant increase in RS content, which shows the importance of other flour components in the process of starch retrogradation.     

Development and characterization of extruded snacks from New Zealand Taewa (Maori potato) flours

Crispy extruded snacks were prepared by mixing ungelatinized dried potato flours from four different Taewa cultivars and a modern potato cultivar with corn flour at two different ratios (25:75; 50:50), and their quality characteristics studied. All of the potato flours showed differences in colour, dry matter content, starch content and pasting characteristics. Among the extrudates prepared with 25% potato flours, Huakaroro snacks showed an L¹ value of 51.71, whereas pure corn flour snacks had the highest L¹ value of 61.22. The b¹ at both levels of potato flour incorporation were lowest for Tutaekuri snacks. The microstructural characteristics of the extrudates such as cell structure and cell wall thickness changed considerably when potato flour was incorporated (50%) in the extruder feed. Moemoe, Tutaekuri and 100% corn flour snacks had the highest toughness, whereas the highest crispness was observed for the Huakaroro snacks. Lower and higher cold peak viscosities of 91 and 597 cP were observed for corn and Tutaekuri extrudates (in powdered form), respectively. The extrudates with 50% potato flour had higher breakdown and lower final viscosity than those containing 25% flour. The peak G′ values were highest for 100% corn, Moemoe and Karuparera snack pastes.     

Effect of Different Soaking Time and Boiling on the Proximate Composition and Functional Properties of Sprouted Sesame Seed Flour

The effect of soaking time on the proximate composition and functional properties of sprouted sesame seed flour were investigated. Sesame seed samples were cleaned and pretreated by soaking in clean water for 8, 10, 12, 14 and 16 h. One batch was sprouted for 36 h and another portion was sprouted and then boiled (100 °C for 20 min), dried, milled into flours and subjected to further analysis. The raw (unsprouted) sample was used as control. The proximate composition and the functional properties were determined for each of the samples and the result showed deviations in nutrient content from the raw seed flour. Moisture and protein content was increased by soaking and sprouting but reduced after boiling from a value of (4.99% and 47.64%) to (4.92% and 42.06%) respectively, for the 10 h soaked sample. Fat, crude fibre, ash and carbohydrate contents were reduced by soaking and sprouting while boiling of the sprouted seeds increased the fat and carbohydrate content. Soaking, sprouting and boiling significantly affected the functional properties of the flour (p < 0.05). Soaking and sprouting reduced the bulk density and dispersion of the samples from an initial value of (0.83% and 67.50%) for the unsprouted seed flour to a value of (0.71% and 59.00%) in 10 h soaked samples but increased slightly in most of the soaked sprouted-boiled samples. Thus, soaking of sesame seeds for 12–14 h before sprouting can be used to improve the proximate composition and functional properties of sesame seeds, hence, increase the utilization of the flour.     

甘梅味紫薯山药夹心薯片的加工工艺研究

以紫薯粉、山药粉、白面、甘梅粉为主要原料,以感官评定为标准,通过单因素实验,正交试验,研究甘梅味紫薯山药夹心薯片的最优工艺。结果显示甘梅味紫薯山药夹心薯片的最佳配方为紫薯粉添加量20%、白面添加量75%、甘梅粉添加量3.75%(以山药粉添加量为基准)。于烤箱中烘烤(设置烤箱上层温度为150℃、下层温度为240℃)110 s,翻面,再烘烤110s,取出,加入1.25%(以山药粉添加量为基准)的果酱,即可得到酸甜可口,香气诱人,营养丰富的甘梅味紫薯山药夹心薯片。     

Use of continuous bubble separation process for separating and recovering starch and mucilage from yam (Dioscorea pseudojaponica yamamoto)

The yam (Dioscorea pseudojaponica Yamamoto) tuber is abundant in both starch and mucilage. It is difficult to separate yam starch from its tuber because of the presence of viscous polysaccharide polymers (glycoprotein). The surface-active polysaccharide-containing complexes are capable of forming foams. The goal of this study was to develop a continuous bubble separation process for separating and recovering starch and mucilage from yam tubers in the absence of undesirable chemical additives or treatments. The results showed that the highest concentration (13.2 g/100 g) of yam slurry mucilage was obtained with a reasonably high yield of recovered starch (91.2 g/100 g) by treating the starch paste with 1 g/100 g Viscozyme^® L and Pectinex^® Ultra SP-L. In comparison with the total amount of yam fed into the system, the yield of soluble carbohydrates and protein in separated mucilage were 98.8 g/100 g and 74.1 g/100 g, respectively. The chemical composition of the separated freeze-dried mucilage was shown to be high in soluble carbohydrates (52.5 g/100 g, dry basis) and protein (40.3 g/100 g, dry basis). A very low amount of starch (0.8 g/100 g) remained in the mucilage. This method is simple, low in operational and capital costs, and especially suitable for polysaccharide–protein-containing complexes recovering from a starch-containing system.     

Effects of osmo-dehydration,blanching and semi-ripening on the viscoelastic,water activity and colorimetry properties of flour from three cultivars of plantain (Musa AAB)

The viscoelastic properties, water activity and colorimetry measurements of plantain flour produced by hot-air dehydration of three cultivars, French Horn, False Horn and True Horn local plantains were studied. Treatments given to the plantains before the hot-air dehydration were osmo-dehydration, hot-water blanching and semi-ripening and fresh unripe. The best pasting characteristics occurred for True Horn local and False Horn osmo-dehydrated flours. Water activity and moisture content were 0.27–0.39 a_w and 5.08–7.25%, respectively with the lowest recorded for False Horn osmo-dehydrated flour. Colour parameters were in the range of 87.34–79.56 and 15.71–26.74 for L? and b?, respectively. The least browning colour (a?) was exhibited by True Horn local and False Horn osmo-dehydrated flours. Statistical significances (P < 0.05) were recorded for water activity, moisture content and a? colour parameter between process treatments for fresh unripe, semi-ripe, osmo-dehydration and blanching whereas no statistically significances occurred for varietal differences for False Horn, True Horn local and French Horn plantains. However, the viscoelastic properties were significant for F-ratios at P > 0.05. Process treatments of osmo-dehydration, blanching and semi-ripening contribute significantly to the differences for water activity, moisture content, browning effect and viscoelastic properties compared to plantain varieties, with osmo-dehydration emerging as the best treatment method.Industrial relevanceThis work is a representation of peculiar differences for water activity, moisture content, non-enzymatic browning effect and viscoelastic properties among process treatments of osmo-dehydration, blanching, semi-ripening and fresh unripe. Important results were obtained for the flour industries for decisions on selecting osmo-dehydration among the process treatments for plantain (Musa AAB) flour in order to take advantage of the consumer demand for plantain flour.     

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

The 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%.     

干燥方法对山药粉性质的影响

通过真空干燥、冷冻真空干燥和喷雾干燥制备山药生/熟粉,研究其流变特性、糊化特性和消化性质,初步探究其变化机制。结果表明,山药生粉具有较高的成糊温度,山药熟粉中冷冻真空干燥山药熟粉的峰值黏度最高(3619.50 cP)。不同干燥方法干燥的山药粉均呈非牛顿流体特性,冷冻真空干燥的山药熟粉的粘弹性最高;山药生粉呈现完整的淀粉颗粒形态,山药熟粉的颗粒形貌差异较大。熟化处理使山药粉抗性淀粉含量显著降低(P<0.05)。熟粉中真空干燥山药熟粉的抗性淀粉含量最高(56.11%)。三种干燥方法中,冷冻真空干燥能较好的保留山药粉的原有理化特性。     

Effect of Boiling and Frying on the Total Carbohydrate,Vitamin C and Mineral Contents of Irish (Solanun tuberosum) and Sweet (Ipomea batatas) Potato Tubers

In a study aimed at ascertaining whether boiling or frying best conserves nutrients; since the two methods are commonly adapted in Nigeria, the effect of boiling and frying on total carbohydrate, vitamin C and mineral contents of Irish (Solanum tuberosum) and sweet (Ipomea batatas) potato tubers were investigated. The determination of total carbohydrate was carried out using the phenol-sulphuric acid method and the spectrophotometric method was used to determine vitamin C content at 520 nm. The minerals evaluated are iron, zinc, magnesium, sodium, calcium and copper. These were determined by the atomic absorption spectrophotometric method. There was no significant difference (p > 0.05) in the total carbohydrate content of the boiled and fried sweet and Irish potatoes compared with their raw tubers. There was significant difference (p < 0.05) in the vitamin C content of the boiled and fried potato tubers. Boiling and frying of Irish potato resulted in a loss of 37.34 mg/100 ml (63.90%) and 30.44 mg/100 ml (53.90%) vitamin C respectively. Boiled sweet potato lost 51.16 mg/100 ml (72.37%) and fried lost 43.05 mg/100 ml (60.90%) of vitamin C. The mineral compositions of the boiled and fried Irish and sweet potatoes were significantly different (p < 0.05) from their raw tubers. Boiling retained more iron and copper while frying retained more zinc, magnesium, sodium and calcium in both Irish and sweet potato tubers. Boiling retained more carbohydrate while frying retained more vitamin C and minerals.     

Studies on the Characteristic Properties of Fermented,Sun-Dried Orange-Fleshed Sweet Potato Flour

Microbiological, functional, chemical and sensory properties of flours of two (2) cultivars of orange-fleshed sweet potato (centinnial and CIP 440293) being multiplied for distribution in South East and South-South Nigeria were investigated using standard techniques. The flours were observed to have good functional properties and high dry matter contents which were respectively 88.09 ± 0.00% and 86.0 ± 0.00%. The respective values for fat content (0.85 ± 0.00% and 1.75 ± 0.00 %), ash content (2.04 ± 0.00% and 2.40 ± 0.42%) and crude fibre content (2.90 ± 0.28% and 2.67 ± 0.00%) were low but the respective levels of carotenoids values (3.74 ± 0.00 and 5.28 ± 0.00 μg/g) were high indicating a promising source of pro-vitamin A. The sensory evaluation had no statistical difference among the parameters. The flours had high nutritive values with good functional and sensory properties. The microbial loads were within the acceptable limit of < 10⁵ recommended by ICMSF, making the flour samples microbiologically safe and with appropriate packaging, the shelf life could be extended under good storage conditions.     

Chemical Composition and Effect of Processing and Flour Particle Size on Physicochemical and Organoleptic Properties of Cocoyam (Colocasia esculenta var. esculenta) Flour

This work investigated the chemical composition of cocoyam corms and cormels and the effect of processing and particle size on the physicochemical and organoleptic properties of the flours for use as soup thickener. Fresh cocoyam corms and cormels were peeled, sliced, washed, divided into four parts that were variously blanched, sulphited and sulphited/blanched. The control was not treated. The slices were sun dried (32 ± 2°C, 3 days), milled and classified with standard sieves into particle sizes of 0.1, 0.2, 0.4, 0.6 mm. The flour samples and fresh corms and cormels were analyzed for the proximate composition, ascorbic acid, anthocyanin and oxalic acid contents. The flours were also analyzed for the pH, bulk density, water and oil absorption capacities and the sensory properties of colour and texture. On dry weight basis, the protein, fat, crude fibre, ash and carbohydrate contents of the corms, cormels and flours were the same (p > 0.05). Ascorbic acid, anthocyanin and oxalic acid contents were respectively reduced from averages of 30.35, 31.58 and 173.88 mg/ 100 g (dry weight) in the corm/cormel to ranges of 8.95 — 16.28, 9.58 — 15.90 and 141.69 — 160.68 mg/ 100 g in the flours. Bulk density was increased (p < 0.05) by blanching and particle size. The water and oil absorption capacities were increased (p < 0.05) by blanching. Colour preference was improved by sulphiting, blanching and decreasing particle size. Texture preference was only affected by particle size. Acceptablility of soups from flours were not affected by treatments and particle sizes.     

Effect of Extrusion Processing on Antioxidant Activities of Corn Extrudates Fortified with Various Chinese Yams (<Emphasis Type="Italic">Dioscorea</Emphasis> sp.)

The purpose of this experiment was to evaluate the effects of extrusion on antioxidant abilities of the extrudates of corn fortified with various (Chinese) yams. The flours from three yam varieties were used, including Dioscorea alata L. var. Tai-nung No.1 (TN1), D. alata L. var. Ta-shan (TS), and Dioscorea doryophora var. Hang-chun (HC). One commercial yam flour (TJ) was also used. Six antioxidant assays were conducted, such as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging effect, oxygen radical absorbance capacity (ORAC) assay, ferrous ion chelating (FIC) ability, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity, superoxide radical scavenging (SORS) assay, and thiobarbituric acid reactive substances (TBARS) assay. The influences of extrusion on the antioxidant activities of corn were determinedly different in different assays, showing a dramatic increase of ABTS value but significant reductions of SORS and TBARS values. The effects of extrusion on antioxidant activities of corn–yam mixtures varied with yams in different assays. Overall, extrusion processing increased the TBARS inhibition ability for all yams and generally had no negative impact on DPPH, ORAC, FIC, and ABTS antioxidant abilities for most yams in corn–yam extrudates. The involvement of the addition of yam to the antioxidant activities of corn–yam extrudates during extrusion could be suggested through two different possible approaches, the effects of extrusion on the antioxidant activities of yams (susceptible, resistant, or improved), and the effects of added yams on the antioxidant activities of corn during extrusion.     

Physical and structural changes induced by high pressure on corn starch,rice flour and waxy rice flour

The impact of high pressure (HP) processing on corn starch, rice flour and waxy rice flour was investigated as a function of pressure level (400 MPa; 600 MPa), pressure holding time (5 min; 10 min), and temperature (20 °C; 40 °C). Samples were pre-conditioned (final moisture level: 40 g/100 g) before HP treatments. Both the HP treated and the untreated raw materials were evaluated for pasting properties and solvent retention capacity, and investigated by differential scanning calorimetry, X-ray diffractometry and environmental scanning electron microscopy. Different pasting behaviors and solvent retention capacities were evidenced according to the applied pressure. Corn starch presented a slower gelatinization trend when treated at 600 MPa. Corn starch and rice flour treated at 600 MPa showed a higher retention capacity of carbonate and lactic acid solvents, respectively. Differential scanning calorimetry and environmental scanning electron microscopy investigations highlighted that HP affected the starch structure of rice flour and corn starch. Few variations were evidenced in waxy rice flour. These results can assist in advancing the HP processing knowledge, as the possibility to successfully process raw samples in a very high sample-to-water concentration level was evidenced.Industrial relevanceThis work investigates the effect of high pressure as a potential technique to modify the processing characteristics of starchy materials without using high temperature. In this case the starches were processed in the powder form - and not as a slurry as in previously reported studies - showing the flexibility of the HP treatment. The relevance for industrial application is the possibility to change the structure of flour starches, and thus modifying the processability of the mentioned products.     

The advantage of using extrusion processing for increasing dietary fibre level in gluten-free products

Gluten-free products generally are not enriched/fortified and frequently are made from refined flour and/or starch. Such products have been found to provide lower amounts of total dietary fibre than their enriched/fortified gluten-containing counterparts.The objective of this study was to increase the level of total dietary fibre in gluten-free products by using extrusion technology and by incorporating a number of different fruits and vegetables, such as apple, beetroot, carrot, cranberry and gluten-free Teff flour cereal. The materials were added at the level of 30% into the gluten-free balanced formulation (control) made from rice flour, potato starch, corn starch, milk powder and soya flour. Different process conditions, such as water feed rate 12%, solid feed rate 15–25 kg/h, screw speed 200–350 rpm, barrel temperatures: 80 °C at feed entry and 80–150 °C at die exit were used. Pressure, material temperature and torque were monitored during extrusion runs. The relationships and interactions between raw ingredients, extrusion processing parameters and resulting extrudate nutritional and textural properties were investigated.The results of this study clearly show that extrusion technology has the potential to increase the levels of total dietary fibre in gluten-free products made from vegetables, fruits and gluten-free cereals.     

Physical properties of acetylated and enzyme-modified potato and sweet potato flours

ABSTRACT:  Textural profile, pasting behavior, gelatinization characteristics, sedimentation volume, and gel consistency of acetylated (Ac) and enzyme (glucoamylase)-modified (EM) potato and sweet potato flours have been investigated to determine their suitability in products such as baked goods, soup, and pudding. Dough hardness of Ac and EM samples was significantly higher than their native samples ( P < 0.01). Dough cohesiveness of modified potato did not change, while it decreased in modified sweet potato. With increase in moisture, textural properties of modified samples, in general, showed reduced values. Rapid Visco Analyser showed least pasting viscosities of Ac flours due to restricted swelling of starch granules while EM flours exhibited high viscosities. Acetylated samples showed reduced gelatinization temperature (GT), and enthalpy (ΔH) compared to native samples, whereas enzyme-treated samples showed no significant changes in GT, indicating their comparable crystallinity values with those of native samples. Modified flour samples had lower sediment volumes and gel consistency, and the gel consistency of EM flour correlated with its cold paste viscosity.     

Physicochemical,functional and cooking properties of under explored legumes,Canavalia of the southwest coast of India

Nutritionally potential under explored wild legumes viz., Canavalia cathartica and Canavalia maritima are widely distributed in mangroves and sand dunes, respectively, in Southwest coast of India. Physicochemical, functional and cooking properties of dried seeds of these legumes have been evaluated. Seeds and cotyledons of C. cathartica are larger and possessing higher hydration and swelling capacity than that of C. maritima indicating higher permeability and softness. The crude protein of C. maritima and C. cathartica were found to be higher than common pulses. The pH vs. protein solubility profile was almost similar with minimum solubility at pH 4 (27.8–28.1%). C. maritima showed higher oil absorption capacity (1.53 ml/g) as well as water absorption (0.1 M) capacity. The gelation capacity was minimal at 0.1 M NaCl and pH 4 for both the seed flours. Addition of carbohydrates (starch, lactose, maltose and sucrose) reduced the lowest gelling capacity of C. maritima except for maltose in C. cathartica. Emulsifying activity (EA) and emulsifying stability (ES) diminished with increasing concentration of flours. Minimum EA and ES were attained at pH 4 and maximum at pH 10 in both seed flours. Maximum EA for C. cathartica and C. maritima (62% vs. 72.6%) was attained at 0.4 M NaCl. The ES vs. flour concentration, pH and ionic strength profiles did not differ much between C. maritima and C. cathartica. Peak foam capacity (FC) and stability (FS) were achieved at 6% (w/v) of C. maritima flour, while the same was attained at 8% (w/v) of C. cathartica. The FC and FS of the seed flours improved with increasing pH (pH 2–10). C. maritima flour exhibited the better FC (27.7%), while C. cathartica exhibited better FS (44.42%) at pH 10. Although highest FC was attained at 0.4 M NaCl in both flours, C. maritima was found to be superior (30.5% vs. 28.5%). The flour of C. maritima attained the highest FS at 0.2 M NaCl than C. cathartica (0.4 M NaCl). The minimum cooking time for cotyledons of C. cathartica was more and higher gruel solid loss was reported due to its high L/B ratio. The Pearson correlation coefficients revealed that functional properties of seed flours vary due to their chemical composition.     

Effects of Processing on the Nutrient Composition of False Yam (Icacina trichantha) Flour

False yam (Icacina trichantha) tubers were processed into different flour samples: the raw; steeped-sun-dried; steeped- oven-dried; blanched-sun-dried and blanched-oven-dried samples. The nutrient composition: proximate and mineral elements contents of the flour samples were studied. The lipid, protein and carbohydrate contents of the samples ranged between 1.77 to 5.76%, 3.01 to 60.3% and 85.56 to 93.31% respectively, while the energy values ranged between 394.27 to 412.46 Kcal. Concentration of potassium, sodium, calcium and iron (among others) ranged between 20.835 and 31.51 mg/l, 2.409 and 18.890 mg/l, 90.250 and 112.550 mg/l to 0.777 and 2.840 mg/l respectively. False yam tuber, apart from being a good source of energy for man, is rich in mineral elements (potassium, sodium and calcium).Processing affected the levels of nutrients, in the flour samples.     

紫薯中多酚氧化酶活性的研究及褐变控制

研究紫薯组织中多酚氧化酶(PPO)的活性,最适pH值、最适温度等特性,并在此基础上,研究加热温度、加热时间、抗坏血酸和柠檬酸添加量对PPO褐变的抑制效果。结果表明：紫薯PPO最适pH值范围为5.5～7.5,最适温度为30℃。在较好的分离淀粉的前提下,最佳抑制褐变条件是：加热温度80℃、加热时间10min、抗坏血酸添加量0.9‰、柠檬酸添加量1.2g/L。     

Nutritional quality of yam (Dioscorea dumetorum and D rotundata) flours for growing rats

The digestibility and metabolism of diets based on flours prepared from raw, boiled or steamed tubers of the sweet yam (Dioscorea dumetorum) were evaluated in growing albino rats by the balance method in comparison with diets containing similar flours from the popular white yam (D rotundata). The results show that whatever their method of preparation, flours from D dumetorum promote higher growth rate and have higher nutritional value in the growing rat than corresponding D rotundata flours. This can be attributed to the good digestibility of D dumetorum starch which facilitates digestibility and absorption of nitrogen and other nutrients. Moisture-heat treatment of tubers before processing into flour improves the nutritional value, especially for D rotundata.