The effects of variety,drying procedure,fineness of grinding and dietary inclusion level on the bioavailability of Cassava (Manihot esculenta crantz) starch

The bioavailability of raw cassava starch from dried, whole roots, as affected by a number of variables, both inherent and processing-induced, was determined in a series of feeding trials using the rat as a test animal. Apparent starch digestibility was in excess of 99% and was unaffected by cassava variety, cyanide content, drying process, fineness of grinding, dietary inclusion level (up to 50% of the diet) and age of the animal. A high level of residual cyanide (406.6 mg kg^?1 dried cassava chips) reduced feed intake and weight gain. Since the floor-drying procedure, whilst effectively reducing the cyanide to an acceptable level, was without effect on the digestibility of cassava starch, it is recommended that this process be adopted for drying high cyanide cultivars of cassava destined for the animal feed market. This will allow cassava to be incorporated in the diet at a higher inclusion level with no undesirable effects on animal performance.     

Food components affecting the oil absorption and crispness of fried batter

Frying batters are used to add value to a product by improving texture, flavour, weight and volume and reducing water loss during frying which, in turn, lessens oil absorption. The physical characteristics of fried batters were studied using model systems based on rice flours. Crispness was positively correlated with amylose content, while oil absorption was negatively correlated with amylose content. Addition of pregelatinised rice flour improved crispness but resulted in increased oil absorption because of the porous nature of the fried product. Amongst the proteins (egg yolk, gluten, skimmed milk, whey and ovalbumin) studied, ovalbumin was able to reduce oil absorption and improve the crispness of the fried batter. Addition of calcium chloride also reduced oil absorption and improved crispness, while a little oil reduced the oil content of the fried batter and improved its taste. Addition of ovalbumin, oil or calcium chloride beyond the optimal levels reduced crispness and increased oil absorption in a linear manner. Modified tapioca starch and diglyceride emulsifiers improved crispness but increased oil absorption. The amount of water added to the formulation affected the physical characteristics of the fried batter. The optimal formulation for a crisp frying batter with reasonably low oil absorption was an amylose/amylopectin ratio of about 18: 67; with (g kg⁻¹) 850 pregelatinised rice flour; up to 150 modified tapioca starch; 30 ovalbumin; 1 calcium chloride; 20 oil; 20 emulsifier and a water/flour ratio of 2:1. © 1998 Society of Chemical Industry.     

Influence of Cassava Storage Root Development and Environmental Conditions on Starch Granule Size Distribution

Among starch producing crops, cassava has a higher carbohydrate production than others under suboptimal conditions, more than 163×10⁶ t of cassava starch are produced world‐wide each year and are used for direct human consumption, animal feeds and as raw material for a wide range of industrial products. A basic knowledge of starch characteristics and storage process is required to improve cassava starch quality and quantity. This report describes a comparative study of morphology, starch granule size distribution and amylose content in cassava storage roots grown under different conditions. Microscopic evaluation reveals that storage roots contain larger starch granules than fibrous roots. The study on three Asian cassava cultivars demonstrates the increment of starch granule size from outermost to innermost layers of storage root, while no significant change is observed in amylose content. The effects of developmental stage and growing season on cassava starch reveals that granule size is significantly influenced by both factors, while the amylose contents only fluctuate in a narrow range. The size of the starch granules increases particularly in the first six months after cultivation. Planting cassava in the beginning of the wet season in Asia yields larger granule sizes than planting in the dry season. The significance of this study lies in better understanding optimal growing conditions for improved starch characteristics and production, leading to a better quality agricultural production of this important food and materials crop.     

Cyanogenic potential of randomly sampled fresh and processed cassava on retail sale in Singapore

A random sample of fresh cassava roots and cassava products, purchased at various retail outlets in Singapore during 2016–2017, had total cyanogenic potential (CNp–expressed as mean ± standard deviation, mg kg⁻¹ HCN, fresh weight basis) as follows: fresh roots (n = 66) from three SE Asian countries, 59.0 ± 19.2; peeled chilled root pieces from Malaysia (20 × 1-kg packs), 38.5 ± 16.5; cassava flour from Indonesia (8 × 1-kg packs), 11.7 ± 8.2; dried Indonesian chips for home frying (5 × 250 g packs), 61.6 ± 16.5; one pack (120 g) of Malaysian ready-to-eat (RTE) chips, 17.1 ± 3.2. CNp in all flour and RTE chips was below 20 mg kg⁻¹. The majority of fresh roots (59.1%) and packs of dried chips (80%), and 15% of packs of peeled chilled root parenchyma, exceeded the Codex Alimentarius limit (50 mg kg⁻¹) for ‘sweet’ (boil-and-eat) cassava.     

Kinetics of moisture loss and fat absorption during frying for different varieties of plantain

This study compares the behaviour of four varieties of green plantain at their initial stage of maturity during the frying process. A variety traditionally used for the manufacture of thin plantain chips (Dominico Hartón commun) and three other varieties found in Latin America (Bouroukou, Bluggoe and FHIA 21) were used. The varieties were characterised by measuring initial moisture content, total sugar content, reducing sugar content, starch content and apparent density. Moisture loss and fat uptake kinetics during frying were assessed at different temperatures (145, 165 and 185°C). With all four varieties, the time required to produce a final moisture content of 40 g kg⁻¹ (wb) was about 90 s at 165°C and 185°C. Use of a lower temperature (145°C) extended the processing time to 150 s. On the other hand, temperature had very little effect on fat content, which proved to be essentially determined by the variety of plantain. Fat content for final water content levels of 40 g kg⁻¹ (wb) ranged from 300 g kg⁻¹ (wb) for Bouroukou to 450 g kg⁻¹ (wb) for Bluggoe regardless of the processing temperature. © 1999 Society of Chemical Industry     

Effect of superheated steam prefrying treatment on the quality of potato chips

Superheated steam drying (SSD) was used as a prefrying treatment prior to deep‐fat frying for potato slices. The effect of SSD at 130, 150 or 180 °C and steam velocity of 2.0 m s^?1 on the fat uptake, colour and texture of fried potato chips was evaluated; microstructure and degree of starch gelatinization were also evaluated to help explain the fat uptake results. SSD and frying yielded potato chips with the fat content from 0.263 ± 0.002 to 0.304 ± 0.002 kg kg^?1 (d.b.), while frying without SSD led to chips with the fat content as high as 0.359 ± 0.003 kg kg^?1 (d.b.). SSD did not promote starch gelatinization. Lower fat uptake was correlated to modified surface structure and lower moisture content of potato slices prior to frying. Frying with/without SSD pretreatment yielded potato chips of similar hardness, crispness and lightness. On the other hand, SSD significantly increased redness and yellowness of the fried chips.     

双波长分光光度法测定木薯块根淀粉含量的动态变化

以双波长分光光度法测定SC201、SC205、GR891和GR911共4个木薯品种生育期块根中直链淀粉与支链淀粉含量的动态变化.结果表明,4个木薯品种块根直链淀粉的含量是随生育期的延长而逐渐增加的,而支链淀粉的含量却缓慢下降,支链淀粉/直链淀粉的比例呈现下降趋势,到12月份4个品种的这一比例已接近相同;以鲜重计的总淀粉含量,4个品种均呈逐渐增加的趋势;而以干重计的总淀粉含量的变化则4个品种表现不一致.研究初步揭示了木薯块根直链淀粉、支链淀粉和总淀粉含量的积累规律.     

Resistant starch production from mango starch using a single‐screw extruder

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg⁻¹) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg⁻¹), but low WAI values (70–77 g kg⁻¹) were obtained at moisture contents between 200 and 300 g kg⁻¹ and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg⁻¹), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg⁻¹), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry     

复合马铃薯片油炸工艺研究

以马铃薯淀粉和马铃薯全粉为主要原料,对复合马铃薯片的油炸工艺参数进行了研究。采用正交试验,确定了生产低含油量、低丙烯酰胺(AA)含量、高脆度复合薯片的最佳油炸工艺参数,即油炸前坯料的含水量控制在20%左右,含盐量2%左右,油温以160℃为佳,炸制时间为40 s,油炸薯片丙烯酰胺含量为0.28 mg/kg,在市售薯片基础上降低26.32%;含油量为23.36%,降低了1.47个百分点。     

Effect of Degree of Starch Gelatinization on Quality Attributes of Fried Tortilla Chips

ABSTRACT: The effect of degree of starch gelatinization on the quality attributes of tortilla chips was studied. Three different samples were prepared: control (45% of starch gelatinized before frying), freeze-dried (5% of starch gelatinized before frying), and steamed-baked tortilla chips (87% starch gelatinized before frying). Compared to the control chips, the steamed-baked tortillas produced chips with lower oil content. They shrunk the most and showed a high degree of puffiness and lower crunchiness. Their texture was harder and not very crunchy. The majority of the oil in these chips was located at the surface. The freeze-dried tortilla yielded chips with high oil content. The texture was soft, and the porosity was very low, providing unacceptable characteristics in tortilla chips.     

Starch determination,amylose content and susceptibility to in vitro amylolysis in flours from the roots of 25 cassava varieties

BACKGROUND: Cassava cultivars are classified following different criteria, such as cyanogenic glucoside content or starch content. Here, flours from the roots of 25 cassava varieties cultivated simultaneously in a single plantation, were characterized in terms of starch content (SC), amylose content (AC), α‐amylolysis index (AI) and gel formation ability. Resistant starch content (RS) was measured in 10 of the samples. RESULTS: Cassava flours exhibited high SC, low AC and low AI values, with differences among varieties. Cluster analysis based on these parameters divided the cultivars in four groups differing mainly in SC and AC. AI and AC were inversely correlated (r = ? 0.59, P < 0.05) in 18 of the cultivars, suggesting AC as an important factor governing the susceptibility to enzymatic hydrolysis of starch in raw cassava. Differences in susceptibility to amylolysis, assessed by RS, were also recorded in the sample subset analyzed. Most flours yielded pastes or gels upon heating and cooling. Gels differed in their subjective grade of firmness, but none exhibited syneresis, confirming the low retrogradation proclivity of cassava starch. CONCLUSION: Some differences were found among cassava samples, which may be ascribed to inter‐cultivar variation. This information may have application in further agronomic studies or for developing industrial uses for this crop. Copyright © 2011 Society of Chemical Industry     

Changes in scopoletin concentration in cassava chips from four varieties during storage

BACKGROUND: The use of the root crop cassava (Manihot esculenta Crantz) is constrained by its rapid deterioration after harvesting. Chemical and spectroscopic examination earlier revealed the accumulation of the four hydroxycoumarins esculetin, esculin, scopolin and scopoletin derived from the phenylpropanoid pathway, during the time course of postharvest deterioration. In this investigation the scopoletin level in parenchymal samples of four cassava cultivars used in Benin, i.e. Kpaki kpika, Kpaki soan, Logoguesse kotorou and BEN 86052, was investigated by high‐performance liquid chromatography (HPLC). RESULTS: Presence was shown in all four varieties with a mean in fresh roots between 4.1 and 11.1 mg kg^?1 dry weight. A strong increase in the content of scopoletin was noticed after a peeling and drying process (6 days) for chip production, the mean content reaching 242.5 mg kg^?1 dry weight in the cultivar BEN 86052. After 3 months of storage this had decreased to 0.7 mg kg^?1 dry weight. CONCLUSION: Strong accumulation of scopoletin in cassava roots used for chip production in Benin is followed by a decrease in its concentration. Copyright © 2011 Society of Chemical Industry     

Determination of acrylamide content of food products in Korea

Acrylamide (AA) contents of commercial market‐purchased foods and of traditional home‐cooked Korean foods were investigated. The effect of cooking method on AA amount in potatoes was also studied. AA contents of roasted barley and corn ranged from 116 to 449 µg kg^?1 and of chips ranged from 12 to 3241 µg kg^?1, representing a very high variation in AA contents among tested samples. Lower levels of AA were found in wheat flour chips compared to potato chips. AA contents of ramen noodles were below 37 µg kg^?1, whether they contained potato starch or not. The AA contents of Korean home‐cooked oil fried foods increased in the following order: yakwa < whole deep‐fried sea tangle < ground and deep‐fried lotus root < ground and pan‐fried lotus root < French fries < ground and pan‐fried potato. Lotus root and garlic also had the potential to produce AA during cooking. Pre‐treatment such as grinding, boiling, freezing and thawing increased the AA formation in oil‐fried potato. Temperature was more influential than time on AA formation during deep‐oil frying. Removing water‐soluble fractions reduced AA content of cooked potatoes. Copyright © 2006 Society of Chemical Industry     

Cyanide content in whole-root chips of ten cassava cultivars and its reduction by oven drying or sun drying on trays

The effect of sun drying on trays for 48 hr and of oven drying in an air-forced oven at 60°C for 24 hr on the cyanide content of chips of ten cassava varieties was studied. Fresh cassava chips from whole roots of these varieties showed significantly different total cyanide contents among them with values in the range of 100–900 mg/kg on a dry matter basis; most of the varieties studied exhibited cyanide contents in the range of 200–600 mg/kg. The free cyanide proportion in the fresh chips was in the range of 30–40% of their total cyanide. Sun and oven drying reduced the cyanide content in the dried chips to approximately 15–30% of the initial cyanide content of fresh chips. In addition, the free cyanide content in dried chips accounted for approximately 60–80% of their total cyanide value.     

Cyanogen content of cassava roots and flour in Indonesia

A survey has been made of the total cyanogen content of cassava roots and products from the cassava growing provinces of Lampung and East, Central and West Java, in Indonesia. Twenty five samples of cassava products were analysed for cyanogens by the acid hydrolysis method and also by the simple picrate kit method. The mean percentage difference between the results was 17%. Thirty samples of cassava starch and other specialised products had a mean cyanogen content of only 5 ppm, whereas 29 samples of cassava flour, chip and gaplek gave a much higher mean cyanogen content of 54 ppm (SD 51). The WHO safe value for cassava flour is 10 ppm and the Indonesian level is 40 ppm. There are four outliers of cyanogen content 140–200 ppm, which would be dangerous to human health. The cyanogen content of starch/chips/gaplek needs to be reduced by using cultivars of lower cyanogen content and by using improved processing methods. Twenty seven samples of cassava roots gave a mean cyanogen content of 19 ppm (SD 14). ©     

Effects of cultivar,nitrogen fertilization rate and environment on yield and grain quality of barley

Ten barley cultivars, including covered and naked types, varying in their content of total starch, amylose, protein and β-glucan, were grown in different years, at various locations and nitrogen fertilization rates. The barley cultivars showed a large variation in yield (3250–6690 kg ha⁻¹), thousand kernel weight (40–50 g), bulk weight (660–815 g litre⁻¹), starch (51–67% of DM), protein (8–15% of DM), β-glucan (3·5–5·9% of DM) and ash (1·9–2·5% of DM). The naked cultivar SW 8775 had the highest starch content and the high amylopectin cultivar (SW 7142-92, waxy) had the lowest. The waxy starch barleys had the highest protein content, while the normal starch barleys (Golf and Lina) had the lowest protein content at each N-rate. Higher content of β-glucan was found in the waxy cultivars (5·0–5·9% of DM) and high amylose cultivars (5·6–5·9% of DM) than in the other barley cultivars (3·5–4·8% of DM). The results were evaluated by analysis of variance (ANOVA) and principal component analysis (PCA), and both confirmed that nitrogen fertilization rate was of great importance for the protein content. PCA revealed that protein and β-glucan were negatively correlated with starch and yield. The ANOVA showed that the cultivar factor was significant for all variables, but especially for the β-glucan content, which responded differently to the nitrogen fertilization rate during the 2 years. In this study, environmental effects were generally of less importance than the barley cultivars for the different variables. © 1998 Society of Chemical Industry.     

Effects of temperature on the physicochemical properties of starches extracted from microtubers grown from different potato cultivars

Twelve potato cultivars were grown as microtubers in constant environment chambers at two temperatures in total darkness for 28 days. For starch extracted from microtubers grown at 12 or 22 °C, the amylose content ranged from 25.0 to 29.0% (average 27.3 ± 1.4%) or 29.5 to 32.7% (average 30.9 ± 1.4%), the amylose/amylopectin ratio from 1:2.5 to 1:3.0 (average 1:2.7) or 1:2.1 to 1:2.4 (average 1:2.2) and the phosphorus content from 0.41 to 0.93 g kg⁻¹ (average 0.72 g kg⁻¹) or 0.38 to 1.67 g kg⁻¹ (average 0.97 g kg⁻¹) respectively. Two major fractions (F1 and F2) were obtained for isoamylase‐debranched starch (amylopectin), with the chain length (CL) averaging 56 ± 3 or 55 ± 1 for F1 and 20 ± 1 or 21 ± 1 for F2 from 12 or 22 °C growth temperature respectively. Peak gelatinisation temperature (T_p) and enthalpy (ΔH) were influenced strongly by growth temperature, with T_p ranging from 60.8 to 64.5 °C (average 62.1 ± 1.0 °C) or 66.9 to 69.6 °C (average 68.2 ± 0.9 °C) and ΔH from 13.3 to 16.9 J g⁻¹ (average 14.8 ± 1.0 J g⁻¹) or 11.3 to 19.5 J g⁻¹ (average 16.3 ± 2.4 J g⁻¹) from 12 or 22 °C growth temperature respectively. The collective data generated at 12 °C were generally more comparable to data published elsewhere (but discussed in the text) for the same potato cultivars grown in field plots (Perthshire). However, there were cultivar specific responses to field or constant environment chambers which make direct comparisons between starches produced from the two systems subject to some variation. Copyright © 2004 Society of Chemical Industry     

Chemical assay of cyanide levels of short-time-fermented cassava products in the Abraka area of Delta State,Nigeria

Five cassava products, commonly consumed in and around the Abraka area of Delta State, Nigeria were analysed for their cyanide levels. This study, to determine safe levels of cyanide, became necessary as the fermentation time in the processing of these products has been observed to be drastically shortened to as low as 6 h for quick economic returns. In all the products, the cyanide levels were reduced from 30.0–58.0 mg HCN equivalent kg⁻¹ of product. These levels fall below the reported 30.0 mg HCN equivalent kg⁻¹ safe (fresh weight) of raw cassava to 5.4–24.0 mg HCN equivalent kg⁻¹ level for cassava products. Nevertheless, some of the products containing up to 20.0–26.5 g HCN equivalent kg⁻¹ of products are dangerous to health as these levels are higher than the 20.0 mg HCN equivalent kg⁻¹ safe level recommended by the Standard Organization of Nigeria. The current practice of short-time fermentation should therefore be discouraged.     

Carbohydrate composition and content of organic acids in fresh and stored apples

The contents of low‐molecular‐weight carbohydrates (LMWC; sorbitol, glucose, fructose and sucrose), starch, dietary fibre and organic acids were determined in seven apple cultivars at the start and end of the consumption interval. The cultivars included were Summered, Aroma, Ingrid Marie, Cox Orange, Mutzu, Belle de Boskoop and Jonagold. The total content of LMWC ranged between 615 and 716 g kg⁻¹ dry matter (DM). The dominating sugar was fructose, corresponding to on average 57% (range 48–62%) of the total LMWC. However, in Cox Orange the sucrose content was considerably higher and the fructose and sucrose contents constituted approximately 46% each. Total dietary fibre content was similar in the cultivars (total dietary fibre 160 ± 20 g kg⁻¹ DM), except for Belle de Boskoop which had a higher content (203 g kg⁻¹ DM). Mutzu had a lower proportion of soluble fibre (27% of total dietary fibre) compared with the others (mean 32%). The organic acid content was on average 80 ± 4 g kg⁻¹ DM, except for two of the cultivars (Summered and Belle de Boskoop) which had a higher content (105 ± 6 g kg⁻¹ DM). Interestingly, the organic acid content was only slightly reduced upon storage in the case of Belle de Boskoop, whereas there was a substantial decrease in all the other cultivars (p < 0.001). Sucrose (p < 0.01) and starch (p < 0.05) contents decreased in all cultivars following storage, whereas sorbitol (p < 0.05) and total dietary fibre (p < 0.05) contents increased. It is concluded that the observed differences in composition are of such magnitude that they may affect both nutritional and sensory properties. © 2000 Society of Chemical Industry     

Cassava foliage: Chemical composition,cyanide content and effect of drying on cyanide elimination

The chemical composition and cyanide concentration in the foliage of four cassava cultivars (M Col 113, M Col 22, M Col 1684, CM 342–170) were evaluated at four plant ages (6, 8, 10 and 12 months). The effect on cyanide elimination of sun-drying on a concrete floor and of oven-drying at 60°C was also studied, including some observations on the tannin content of dried foliage. The proximal composition, calcium and phosphorus contents, as well as the amino acid composition of dried cassava foliage compared favourably to that of sun-cured lucerne meal. In most cases, foliage from 6-to 12-month-old plants contained 25 to 30% dry matter, and as dried foliage had 13 to 20% crude protein and 16 to 20% crude fibre. Crude protein and crude fibre were the two chemical constituents which varied the most with plant age. The average gross energy of dried cassava foliage was 4.12 kcal kg^?1 with a range of 3.90 to 4.35 kcal kg^?1. Sun-drying eliminated more cyanide than oven-drying (82 to 94% vs 68 to 76%, respectively) and in addition, most of the cyanide in sun-dried foliage was free cyanide (62 to 77%) whereas only 24 to 36% was found as such in oven-dried foliage. Sun-dried foliage samples had consistently lower tannin content than the corresponding oven-dried samples.