Influence of Heat Pretreatments of Oat Grain on the Viscosity of Flour Slurries

Heat treatment of oat grain had significant effects on the viscosity of flour slurries. Steamed oats produced highly viscous flour slurries, whose viscosity increased with time, whereas the viscosity of flour slurries produced from raw or roasted (104°C for 120 min) oats was much lower and degraded rapidly. Slurry viscosity was correlated with (1→3), (1→4)-β-D -glucan concentration in the flours and treatment of slurries with lichinase lowered viscosity significantly. Effects of steaming were partially reversed by roasting treatment and vice versa. Mixtures of equal amounts of raw and steamed flour resulted in slurries more viscous than either flour alone, but that viscosity degraded after 3 h to less than the mean viscosity of the steamed and raw controls. Water-soluble extracts from steamed flour had about twice the viscosity of raw or roasted flour extracts, but contained only 80% of the (1→3), (1→4)-β-D -glucan present in those extracts. Molecular weight analysis of soluble carbohydrates from raw, roasted and steamed soluble extracts indicated the molecular weight of β-glucans in these extracts was similar. However, if extracts were made from slurries that had incubated for 3 h, extensive degradation of β-glucans was evident in raw and roasted samples. It is likely that enzymic degradation of (1→3),(1→4)-β-D -glucans is responsible for much of the decreased raw and roasted flour slurry viscosity over extended time periods, but different heat treatments appear to also affect (1→3), (1→4)-β-D -glucan polymer interaction. © 1997 SCI.     

淀粉原料焙炒对酱油制曲的影响

本研究以小麦、面粉为淀粉原料,采用焙炒技术,在最佳焙炒时间下分别比较经焙炒处理的小麦、面粉与未经处理的小麦、面粉对酱油成曲的蛋白酶活、氨肽酶活、淀粉酶活、纤维素酶活和氮溶指数（NSI）等理化指标的影响。同时,通过测定酱油大曲酶解液的总糖转化率和蛋白回收率,筛选最佳焙炒时间。实验表明,小麦、面粉的最佳焙炒时间均为20 min,在此条件下,焙炒处理对酱油成曲酶系及理化指标的影响较大。经焙炒的小麦所制成曲较生小麦成曲在中性蛋白酶活、氨肽酶活、纤维素酶活、孢子数和NSI分别提高了13.06%、12.58%、9.92%、37.04%和10.46%;经焙炒的面粉所制成曲较生面粉成曲在中性蛋白酶活、氨肽酶、纤维素酶活、孢子数和NSI分别提高了32.88%、28.17%、18.07%、13.04%和10.79%;但小麦、面粉焙炒后,酱油成曲淀粉酶活略有降低。综上,小麦和面粉的焙炒处理均对成曲的酶系增强及理化指标的提高有一定的促进作用。     

PROTEIN QUALITY OF PROCESSED WHOLE KERNEL GLANDLESS COTTONSEED

Protein quality of raw, cooked and roasted glandless whole kernal cottonseed flour was determined. The adjusted protein efficiency ratio (PER) of cooked (2.10) cottonseed was significantly (P = 0.01) higher than roasted (1.77) cottonseed. Protein retention efficiency (PRE) for roasted cottonseed (58.08) was lower than values for raw (60.54) and cooked (62.95) cottonseed. Relative protein values (RPV) indicated a utlization of 91, 91 and 96% of the protein in raw, roasted and cooked cottonseed, respectively. Cooked glandless cottonseed protein quality was superior to that of raw cottonseed. The roasting process adversely affected protein quality. Supplementation of roasted cottonseed with 0, 0.2, 0.4, 0.6 and 0.8% L-lysine indicated a peak PER response at 0.45%. The adverse effect of roasting on the protein quality of cottonseed was overcome by addition of L-lysine which made the protein quality of roasted cottonseed comparable to that of cooked cottonseed.     

Chemical composition and functional properties of raw and roasted Nigerian benniseed (Sesamum indicum) and bambara groundnut (Vigna subterranean)

Benniseed and bambara groundnut seeds were roasted at 80 and 120 °C for 10–60 min. For both flours, the effects of roasting temperature and time on selected functional properties and chemical composition were determined, as were the effects of pH on the emulsification capacity and nitrogen solubility. The chemical constituents of the raw flours were present at higher concentrations than those of the roasted flours except for fat and ash. Protein concentrates of both flours contained 80.5–81.5% crude protein as the major constituent. Nitrogen solubility was lowest at pH 4.0 for raw and roasted benniseed flour and pH 5.0 for raw and roasted bambara groundnut flour. Roasting generally lowered the nitrogen solubility and increased the water and oil absorption capacities while decreasing the foaming capacity and emulsification capacity of both flours.     

Physicochemical and pasting properties of maize flour as a function of the interactive effect of natural-fermentation and roasting

The effect of natural-fermentation and roasting on maize physicochemical and functional properties were evaluated. Natural fermented maize seeds were soaked for variable times (0, 24 and 48 h) and directly decorticated or roasted before milling into flour. Generally during the 24 to 48 h natural fermentation, total sugars (80.3–92.0 g/100 g) and proteins contents (4.0–7.6 g/100 g) decreased while they significantly increased with soaking. Soluble sugars content of the unroasted maize significantly decreased with fermentation while that of roasted maize significantly increased. Reverse observations were made on soluble proteins. The antinutrients (phytates and total polyphenols) contents of the grains as well as the functional properties of their flours were observed to have been significantly changed following fermentation and roasting. In particular the least gelation concentration (6 to 18 g/100 mL), an important reverse index of gelating power significantly increased with fermentation and roasting. As consequence the viscosity of the fermented maize flours were systematically significantly lower than that of the unfermented flour. Generally while the effects of duration of fermentation and roasting on the viscosity were not consistent, the 48 h natural fermented and roasted flour was observed to particularly produce flours of much lower viscosity. This highlighted the positive effect of combining fermentation and roasting to improve the quality of weaning flour made from maize.     

Effect of thermal processing on the nutritive value of wheat germ protein

Wheat germs are used as industrial products for nourishment so that it was necessary to determine the nutritive value of proteins in raw and in roasted wheat germs (temperature: 130–150 °C for 20 min). Protein quality evaluation has been determined by a biological method - feeding young growing rats. The rats were fed 10% level protein diets, based on raw and roasted wheat germs. The results show that protein of roasted wheat germs has higher digestibility (D) and protein efficiency ratio (PER) than the raw wheat germs which proves that roasting destroyed digestion enzymes inhibitors. Furthermore, the net protein utilization (NPU) has also been improved by roasting. Biological value (BV) of raw germs approximates to the value of roasted germs. The results lead us to the conclusion that roasting saves and improves protein parameters in wheat germs.     

Effects of roasting on phenolics composition and antioxidant activity of peanut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.) kernel flour

The effects of roasting on the phenolics composition and antioxidant activity of peanut (Arachis hypogaea L.) kernel flour were appraised. Peanut kernel flour, with and without skin, were roasted at 160 °C for 10, 20, 30, 40 and 50 min. The resultant changes in the antioxidant activity of roasted peanut kernel flour were assessed by the determinations of total phenolics, 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging capacity, percent inhibition of linoleic acid oxidation and thiobarbituric acid test and compared with those of unroasted kernel flour. It was observed that roasting significantly (p < 0.05) increased the antioxidant activity of the peanut kernel flour. HPLC analysis revealed the detection of three phenolic acids (p-hydroxybenzoic, chlorogenic, p-coumaric), two flavonols (quercetin, kaempferol), and a stilbene (resveratrol) both in the roasted and unroasted samples. In peanut kernel flour without skin, the contents of the phenolics increased in the initial roasting phase, however, decreased gradually in the later phase (>20 min of roasting time). In contrast, over the course of heating, the amounts of phenolics were noted to be slightly increased in the peanut kernel flour with skin; the most significant (p < 0.05) increase occurred in the concentration of p-coumaric acid and quercetin at 30, 40, and 50 min of roasting. The results of this study reveal that optimum roasting time should be sought to enhancing the antioxidant capacity and phenolics concentration in peanut kernel flour.     

Effect of processing on the protein nutritional value of Canavalia gladiata seeds

Evaluation of protein true digestibility (TD), biological value (BV), and net protein utilization (NPU) of diets containing mature sword bean (Canavalia gladiata), seed flour and grits were carried out with male Sprague-Dawley rats. The seed flour and grits were processed by soaking, cooking, soaking and cooking, autoclaving, and roasting. The TD of processed flour (cooked (84.8), soaked and cooked (76.2), autoclaved (82.0), roasted grits (64.5), and roasted flour (61.2)) were significantly higher (p < 0.05) than in the raw (51.4) and the soaked only grits (35.8). Soaking the grits decreased the TD. The BV of cooked grits and grits cooked after soaking were significantly higher than that of the other processed samples (p < 0.05). However, the BV of the diets containing cooked and soaked and cooked grits were not significantly different. The NPU of the cooked grits (39.4) and grits cooked after soaking (37.6) were significantly higher (p < 0.05) than that of the other processed samples (autoclaved grits (31.0), roasted grits (19.5), roasted flour (10.8), and soaked only grits (1.6)). The NPU of all the processed samples were significantly lower than the reference casein (p < 0.05). The highest protein nutritional quality was obtained by either cooking the grits or by soaking and cooking the grits. In vitro protein digestibility measurements were not well correlated to the true digestibility.     

Changes in volatile flavour components of soybeans during roasting

Volatile concentrates were prepared from whole soybeans, roasted at 200°C for 10, 20 and 30 min, by steam distillation under reduced pressure followed by ether extraction, and analysed by gas chromatography and gas chromatography-mass spectrometry, in comparison with the volatile concentrate from raw soybean flour.Major flavour components of raw soybean, such as n-hexanol, 1-octen-3-ol and n-hexanal, decreased during the course of roasting, but the rate of this decrease was not rapid, especially between 10 and 20 minutes' roasting. During the roasting period, alkylated pyrazines, oxygenated furans, oxygenated pyrroles and phenols were formed or increased markedly. On the other hand, sensory evaluation showed that a flavour change to ‘desirable’ from ‘beany’ or ‘objectionable’ occurred between 10 and 20 minutes' roasting. These results suggest that roast flavour masks the ‘beany’ flavour in soybean.     

Modelling moisture sorption isotherms for maize flour

The sorption isotherm of food material is pertinent in the processing and storage of food products. Adsorption and desorption isotherms for maize flour were investigated using the static gravimetric method over the range of temperature (27–40 °C) and water activity (a_w) (0.10–0.80) commonly experienced in the tropical environment. The experimental data were compared with five widely recommended models in the literature for food sorption isotherms (GAB, modified GAB (MGAB), modified Oswin (MOE), modified Henderson (MHDE), and modified Chung–Pfost (MCE)). The GAB, MGAB, and MOE models were found to be acceptable in predicting the moisture sorption isotherms for maize flour. Overall, the MGAB appears to be most suitable for fitting the adsorption and desorption moisture isotherms data for the maize flour.     

Effect of cultivar and roasting method on composition of roasted soybeans

BACKGROUND: The composition of raw soybeans and the roasting method have an important impact on the quality of roasted soybeans. The objective of the study was to determine the effect of food‐grade soybean cultivars (IA 2064, IA 1008, IA 1008LF, Prairie Brand 299, Asgrow 2247) and roasting method (oil‐ and dry‐roasting) on the composition of roasted soybeans. RESULTS: Moisture content decreased after roasting, with oil‐roasted soybeans having a significantly lower moisture content than the dry‐roasted soybeans. With the exception of the low linolenic acid cultivar (IA 2064), there were no significant differences in total lipid and fatty acid contents of the five cultivars. Oil‐roasted soybeans had significantly higher lipid content than raw and dry‐roasted soybeans owing to the absorption of oil. The soluble sugars and free amino acids contents of the five soybean cultivars were not significantly different. Decreases in the contents of free amino acids, but not soluble sugars, occurred during roasting. Greater reductions were seen in oil‐roasted soybeans because of the higher roasting temperature. CONCLUSION: Roasting method, rather than cultivar, had the greatest effect on the composition of roasted soybeans. The food‐grade soybean cultivars evaluated in this study were similar in composition. Copyright © 2009 Society of Chemical Industry     

Effect of sand roasting and microwave cooking on antioxidant activity of barley

Eight different barley cultivars were roasted in sand and cooked in a microwave oven and evaluated for antioxidant activity (AOA), total phenolic content (TPC), non-enzymatic browning, polyphenol oxidase activity (PPO), total flavonoid content (TFC), reducing power and metal chelating activity. Sand roasting resulted in higher puffing index. Greater increase in yellowness of the roasted flour was brought about by microwave cooking. A significant decrease in TPC (8.5 to 49.6%) and TFC (24.5 to 53.2%) was observed after roasting. The AOA significantly increased (16.8 to 108.2%) after roasting with sand roasted barley exhibiting higher AOA. The reducing power and metal chelating activity significantly increased by up to 77.5% and 78.9%, respectively after roasting with sand roasted samples showing greater effect. The non-enzymatic browning index increased (315 to 774%) and was higher for sand roasted barley. The microwave cooking brought about a greater reduction (45.1 to 76.8%) in PPO activity.     

响应面法优化小龙虾烤箱辅助烤制工艺

以小龙虾为研究对象,探讨烤箱烤制小龙虾的加工工艺,以腌制时间、腌制液盐含量、烤制温度和烤制时间为单因素影响因子,小龙虾的感官评分和弹性为响应值,进行响应面优化分析。然后对烤制小龙虾的营养成分和风味特征进行测定和分析,并以鲜虾和水煮虾作为对照。结果表明：经优化后的小龙虾腌制时间为30 min、腌制液盐含量12 g/100 mL、烤制温度180℃、烤制时间20 min,在此工艺条件下小龙虾的感官评分为9.08分、弹性为3.88 mm,与预测值接近,表明该烤制工艺合理有效;烤制处理条件下单不饱和脂肪酸和多不饱和脂肪酸总含量显著高于鲜虾和水煮虾;烤制之后的小龙虾必需氨基酸和风味氨基酸含量较鲜虾和水煮虾差异明显,主要表现在天冬氨酸、甘氨酸、精氨酸和亮氨酸的损失,其中精氨酸损失最大;电子舌传感器上的烤虾响应值鲜度、咸味和甜味均显著高于鲜虾和水煮虾。适当的烤制有利于虾肉营养物质的保存和鲜香味的挥发,同时有利于产品营养与风味的提高。     

Determination of acrylamide in roasted chestnuts and chestnut-based foods by isotope dilution HPLC-MS/MS

A collaboratively trial tested isotope dilution liquid chromatographic method with positive electrospray ionisation tandem mass spectrometry for the analysis of acrylamide in bakery ware and potato products has been extended to the determination of acrylamide in roasted chestnuts and chestnut-based foods. As chestnuts have a similar composition to potatoes, considerable amounts of acrylamide can be expected, especially in roasted chestnut products. This paper presents the concentrations of acrylamide in 31 different chestnut samples (fresh, roasted, flour, cooked, glazed) that were collected in nine European countries during 2005/2006. The influence of the roasting time on the acrylamide content was also experimentally investigated. A test portion was extracted after homogenisation with water and isotopically labelled acrylamide was added. The extract was centrifuged and the supernatant was cleaned-up in two consecutive solid phase extraction steps. The final extract was analysed by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). An HPLC column based on graphitised carbon was applied for chromatographic separation. Acrylamide concentrations in purchased roasted chestnuts were in the range of <8–1278 μg/kg whereas only low amounts (<4–159 μg/kg) were found in chestnut products. However, the median acrylamide content of the commercial roasted chestnut samples was 90 μg/kg. The influence of the roasting time on the acrylamide content in roasted chestnuts was evaluated too. As with roasted and fried potato products, the roasting time has a significant influence on the acrylamide formation. Therefore, the consumers might be exposed to significant amounts of acrylamide by eating roasted chestnuts, especially when a batch remains in the roasting vessel for too long time.     

Effect of some traditional processing operations on the functional properties of African breadfruit seed (Treculia africana) flour

The effect of germination, fermentation, roasting and defatting on the proximate composition, water absorption capacity (WAC), oil absorption capacity (OAC), foaming capacity (FC), foaming stability (FS), emulsion capacity (EC), emulsion stability (ES), packed bulk density (PBD), least gelation concentration (LGC) and protein solubility (PS) of breadfruit seed flour (BSF) was investigated. WAC, OAC, FC, EC, PBD and LGC obtained are 190-380%; 130.3-200.5%; 2.3-60.4%; 12.4-52.9%; 0.4-0.6 g/ml; 6-12% (w/v) and 200-420%; 176.4-320.6; 4.2-70.8%; 20.2-60.4%; 0.5-0.7 g/ml; 0.5-0.8% (w/v) in the full fat and defatted flours respectively. Foams were more stable in the untreated; least in fermented and roasted samples. Defatting improved the FC, FS and EC; roasting and fermentation reduced EC of full fat BSF; Processing and defatting had no effect on the PBD; roasting and germination increased LGC while defatting and fermentation reduced it. Full fat flours had the lowest PS at pH 4 and the highest at pH 8. Fermented full fat BS flour had the highest PS at pH 5 and 8. Defatted germinated, raw dried and roasted BSF had lowest PS at pH 4; PS of fermented BSF is lowest at pH 3 and highest at pH 2.     

Color and Volatile Analysis of Peanuts Roasted Using Oven and Microwave Technologies

Roasted peanut color and volatiles were evaluated for different time and temperature combinations of roasting. Raw peanuts were oven roasted at 135 to 204 °C, microwave roasted for 1 to 3 min, or combination roasted by microwave and oven roasting for various times and temperatures. Volatiles were measured using selected ion flow tube mass spectrometry. L* values were used to categorize peanuts as under‐roasted, ideally roasted, and over‐roasted. The total roasting time in order to achieve ideal color was not shortened by most of the combination treatments compared to their oven roasted equivalents. Oven before microwave roasting compared to the reverse was found to significantly increase the L* value. Peanuts with the same color had different volatile levels. Hexanal concentrations decreased then increased with roasting. Pyrazine levels increased as roasting time increased, although oven at 177 °C treatments had the highest and microwave treatments had the lowest levels. Volatile levels generally increased as roasting time or temperature increased. Oven 177 °C for 15 min generally had the highest level of volatiles among the roasting treatments tested. Soft independent modeling of class analogies based on volatile levels showed that raw peanuts were the most different, commercial samples were the most similar to each other, and oven, microwave, and combination roasting were all similar in volatile profile.     

Thermal,textural, and physicochemical analysis of corn extrudates enriched with broccoli or olive paste

The growing consumers’ demand for healthier snacks is of high importance and is driving research and industry towards developing novel ready to-eat expanded products. Thus, it would be interesting to enrich these products with additives that possibly lead to highly nutrient products. In the present study, extruded snacks based on corn flour enriched with broccoli or olive paste were developed and studied. Although the addition of broccoli or olive paste in extruded snacks can improve their nutritional properties, the final properties of these products must also be considered. Textural analysis (compression tests), thermal analysis (glass transition temperature), and moisture sorption measurements (sorption isotherms) were performed. A Guggenheim–Anderson–de Boer model has been applied to describe moisture sorption isotherms. Moreover, simple mathematical models were developed in order to correlate textural properties (maximum stress, maximum strain, elasticity parameter, number of cracks) with the process conditions during the extrusion (screw speed, temperature) and the raw materials’ characteristics (moisture content, concentration of broccoli or olive paste). Regression analysis was used to estimate mathematical models’ parameters. The influence of process conditions and raw materials’ characteristics on the measured properties of corn-based snacks enriched with broccoli or olive paste was presented based on the alterations of the estimated parameters.     

Characterisation of phenolic components present in raw and roasted wattle (Acacia victoriae Bentham) seeds

The effect of roasting on the phenolic components of Australian wattle (Acacia victoriae Bentham) seed was investigated. Wattle seeds were roasted at 200 °C for 5–30 min and ground to flour, which were then extracted with 70% acetone. The total phenolic and flavonoid contents of the extracts were determined, and the phenolic components were analysed by reverse phase-high performance liquid chromatography (RP-HPLC) coupled with an on-line post-column reaction system to determine the active antioxidant peaks. The major peaks were then purified by preparative HPLC and identified by gas chromatography–mass spectrometry (GC–MS) analysis. Roasting of wattle seeds resulted in significant increases in its soluble phenolic content. The concentration of total phenolics and flavonoids in the seeds roasted for 30 min was more than nine and four times higher, respectively, than that in the raw seeds. The major phenolic acids present in wattle seeds were found to be succinic and gallic acids, the concentration of which increased by up to 10-fold as a result of roasting.     

PROCESSING AND FUNCTIONAL PROPERTIES OF YAM BEANS (SPHENOSTYLIS STENOCARPA)

The proximate and selected functional properties of five flours from yam bean (YB) made after the grains were not processed (raw) and processed as boiled, fermented, roasted and malted, were determined. The functional properties were water and fat absorption, gelation, emulsification and whippability. An improvement was observed for protein content of flours processed beans compared to raw flour. Fermentation improved the oil content of the flour. The emulsifying and foaming capacities (50.7 and 40.20%, respectively) observed for raw flour were significantly higher than those for the flours from processed bean. Gelation was significantly (P < 0.05) increased and decreased by fermentation and malting of the bean, respectively. The water absorption capacities ranged from 131.9% in raw flour to 218.8% in flour boiled beans. There were no significant (P > 0.05) differences in the fat absorption capacities of all flours except for the one of fermented beans (0.40 mL/g), which was significantly lower than the value (0.73 mL/g) obtained for the flour from boiled beans. Although a high foaming capacity was observed for raw flour, it was less stable when compared with that of the processed bean flours. Overall, YB flour was found to exhibit good functional properties, and has a great potential for use as an ingredient in selected food systems.     

Effect of flaxseed flour addition on physicochemical and sensory properties of functional bread

The importance of polyunsaturated fatty acids (PUFA) in health and nutrition is well recognised. Flaxseed (Linum usitatissimum) has recently gained a lot of attention as functional food because of its unique nutrient profile. In the present work efforts were made to develop omega-3 enriched functional bread using raw and roasted ground flaxseed flour. Initially optimisation of each bread ingredient viz., salt, sugar, and shortening, GMS, yeast and water was carried out on the basis of sensory overall acceptability score. The standardised bread was incorporated with raw and roasted ground flaxseed (5, 10, and 15 g/100 g) flour. The effect of flaxseed incorporation on bread dough rheology parameters viz., dough stickiness and water absorption was studied. Increase in water absorption and dough stickiness was observed with increased flaxseed level. Further breads were evaluated for sensory parameters, colour and texture. The crumb softness increased with increase in flaxseed level. Bread was optimised at 10(g/100 g) flaxseed level based on sensory evaluation.