Increasing Cooking Time Research Articles

米の炊飯過程における水分分布の視覚的・定量的把握

As heating proceeds during the cooking of rice, starch granules within the rice grains absorb water, swell, and then gelatinize. To determine the optimal cooking conditions for various kinds of rice, it is desirable to be able to detect differences in the water absorption of rice grains during cooking. NMR imaging was used to follow changes in the content and distribution of water during the cooking of Nipponbare (Japonica), Khao Dawk Mali (Indica) and High Amylose (Indica) rice. Samples were cooked for various cooking times in closed-glass vials, quenched to stop the cooking process, and then investigated using two-dimensional multi-echo 1H imaging at room temperature. Images obtained from the first-echo revealed changes in the water distribution of the rice grains. T2 images calculated using the echoes were converted into quantitatively reliable contour maps of the water concentrations using an empirical T2 vs. water content calibration determined from a series of water/rice starch mixtures. Japonica rice samples with different milled ratios were also investigated to observe the effect of rice grain husks on water absorption. The degree of gelatinization of rice during cooking was measured by the β-amylase·pullulanase method (BAP) and Fourier-transform infrared spectroscopy (FT-IR/ATR). An FT-IR peak seen at around 1 000 cm-1 increased with increasing cooking time. There was a high correlation in the degree of gelatinization between the FT-IR method and the BAP method.

Effect of cooking time and ingredients on the performance of different starches in white sauces

The effect of white sauce ingredients and increased cooking time at 90 °C on the degree of gelatinization of corn, waxy corn, rice, potato and modified waxy corn starches was studied. The changes in pasting properties, linear viscoelastic properties, and microstructure were determined. In all the native starches in water, a longer cooking time at 90 °C caused greater starch granule swelling and more leaching of solubilized starch polymers into the intergranular space. These effects were more noticeable in the waxy corn and potato starches. The potato starch was the most affected, with complete disruption of the starch granules after 300 s at 90 °C. The microstructural changes which transformed a system characterized by starch granules dispersed in a continuous phase (amylose/amylopectin matrix) into a system with an increase in the continuous phase and a decrease in starch granules were associated with a decrease in system viscoelasticity. The elastic moduli were higher in the sauce than in the starch in water system. However, with the exception of potato starch, the white sauce showed lower viscoelasticity than the starch in water system. The white sauce ingredients decreased the effect of cooking time on the starch gelatinization process, particularly in potato starch.

Changed dynamics in myofibrillar protein aggregation as a consequence of heating time and temperature

The kinetics of protein aggregation induced by cooking were investigated in pig M. Longissimus dorsi. The 4 day aged muscles were cooked either in water or under dry heat conditions for 30 min. Four temperatures from 50 to 100 degrees C were tested for the "in water" cooking mode and an additional temperature of 140 degrees C was tested in the dry condition. Raw and cooked meat specimens were ground in a KCl solution. After delipidation of the meat extract, protein aggregation was evaluated with a laser granulometer (Sysmex FPIA-3000) which enabled reliable and reproducible characterization of particle number, size, and shape distribution using automated imaging techniques. The cooking mode (dry/"in water") did not affect the granulometry measurements. But, increasing cooking time and temperature affected the number, the size, and the shape of particles. An important decrease in particle number was observed during cooking in parallel with a reduction in particle size and a change in circularity. From these data a model with intermediary fibrillar aggregates and final amorphous aggregates was proposed.

Comparison of Soda and Kraft Cooking as a Pretreatment Method for Enzymatic Hydrolysis of Softwood Lignocellulosic Materials

Lignocellulosic materials are composed of cellulose, hemicellulose and lignin. Since cellulose is surrounded by lignin, a pretreatment is required to enhance the contact with enzyme for enzymatic hydrolysis. So far, several methods: grinding, steaming, steam explosion, microwave treatment and so on have been studied for wood, however, it is still difficult to saccharify softwood very efficiently. In this study, soda and kraft cooking for chemical pulping were applied for the pretreatment of softwood (Japanese cedar) shaving. The lignin content of kraft pulp ranged from 12% to 3% with increasing cooking time from 1 to 3 hours. Saccharification efficiency after 1 day increased from 90% to 98% with decreasing the lignin content of kraft pulp. The soda and kraft pulp with the same lignin content showed similar saccharification efficiencies. The longer cooking time realized the smaller lignin content, but at the same time, the loss of carbohydrates was larger. As a result, the yields of sugar to wood were almost constant (40%) with a lignin content up to 10% whether the pretreatment was soda or kraft cooking. Even soda cooking is useful enough as a pretreatment method for saccharification of softwood.

CALIDAD DEL ARROZ DE TIERRAS ALTAS EN FUNCIÓN DEL TIEMPO DE COCCIÓN Y DEL CULTIVAR DE ARROZ

Se han estudiado los efectos que causan el cultivar y el tiempo de cocción en la calidad de granos de cinco cultivares de arroz de tierras altas (BRS Primavera, BRS Pepita, BRS Sertaneja, BRS MG Curinga y BRS Monarca) que fueron cocidos en diferentes tiempos de cocción (0, 10, 20, 30 e 40 min). Se han determinado los contenidos de agua, almidón y amilosa, viscosidad máxima y tendencia a la retrogradación y se realizaron ensayos de cocción (rendimiento, pegajosidad y textura). Los resultados demostraron que cuanto mayor es el tiempo de cocción mayor es la disponibilidad de los contenidos de almidón y de amilosa para sus determinaciones y sus valores difieren entre los cultivares de arroz de tierras altas. Se ha observado sinergismo entre los factores estudiados, aumentando el contenido de agua y disminuyendo la viscosidad máxima y la tendencia a la retrogradación con el aumento del tiempo de cocción se ha notado que los cultivares BRS Pepita y BRS MG Curinga pueden absorber mayor cantidad de agua cuando calientes y presentarse más pegajosos cuando fríos y los cultivares BRS Primavera, BRS Sertaneja y BRS Monarca pueden absorber menor cantidad de agua cuando calientes y sus granos pueden presentarse secos y sueltos y endurecerse después de enfriados.

Effect of different cooking regimes on rhubarb polyphenols

Polyphenolic components, such as anthraquinones and stilbenes, from species of the genus Rheum have been shown to have a range of bioactivities relevant to human health. This paper outlines the polyphenolic composition of edible petioles of garden rhubarb (Rheum rhapontigen) and describes the effects of common cooking methods on total polyphenolic content, anthocyanin content and total antioxidant capacity. Most cooking regimes (fast stewing, slow stewing and baking) except blanching increased total polyphenol content and overall antioxidant capacity, compared to the raw material. The patterns of anthocyanin content and total polyphenol content between the different cooking regimes suggested a balance between two processes; cooking facilitated the release of polyphenol compounds from the rhubarb but also caused breakdown of the released compounds. Baking and slow stewing offered the best maintenance of colour through preservation of anthocyanin and the highest antioxidant capacity. Baking for 20 min provided well-cooked rhubarb with the highest antioxidant capacity and the highest anthocyanin content, which is important for the aesthetic quality of the dish. Liquid chromatography–mass spectrometric (LC–MS) analysis putatively identified over 40 polyphenol components in raw rhubarb, including anthraquinone, stilbene, anthocyanin and flavonol derivatives. Baking caused selective effects on the stability of the different polyphenol components. Initially, the yield of all components increased but there was a drastic decline in the relative stability of anthraquinone aglycones with increasing cooking time and initial evidence for the turnover of other anthraquinone derivatives was obtained.

Effect of cooking time on some nutrient and antinutrient components of bambaragroundnut seeds

The proximate composition, gross energy, mineral composition, percentage sugar, oligosaccharides and antinutrient substances of bambaragroundnut seeds subjected to different cooking times were determined. The seeds were cooked for 30, 60, 90 and 120 min. Results of the proximate analysis showed that only the ether extract and ash were significantly (P < 0.05) reduced as the cooking time increased. In contrast, gross energy values significantly (P < 0.05) increased with increased cooking time. Amongst, the mineral elements assayed, calcium, magnesium and iron were significantly (P < 0.05) increased, while phosphorous, potassium, sodium and copper were reduced significantly (P > 0.05) with inreased cooking time. Percentage sucrose and glucose of bambaragroundnut seeds were significantly (P < 0.05) lowest in the raw form, but increased progressively with increased of cooking time. Raffinose and stachyose levels were reduced significantly by increased cookinf time (P < 0.05) with the least value in seeds cooked for 120 min. Trypsin inhibitor, hemagglutinin and tannin were completely eliminated in seeds cooked for 60 min or longer, but the phytin level was reduced significantly (P < 0.05) by cooking. For a significant detoxification of antinutrient substances and for optimal bioavailability of the component nutrients of bambaragroundnut seeds, an optimum cooking time of 60 min at 100 degrees C is therefore recommended.

Influence of variety, growth location and storage conditions on development of hard-to-cook defect in common bean (&lt;i&gt;Phaseolus vulgaris&lt;/i&gt; L).

Storage of beans, especially at temperatures higher than 25ºC, and relative humidity greater than 65%, lead to development of the hard-to-cook (HTC) defect which results in increased cooking time, fuel and water use. This has a negative effect on acceptability and utilization of beans. This study was aimed at investigating the influence of bean variety, moisture content, growth location and storage containers on the development of HTC defect. Freshly harvested (within one month of storage) beans of varieties K131, K132, NABE4 and NABE 11 collected from farmers were first assessed for susceptibility to the HTC defect and then chemical changes associated with differences in moisture content and storage conditions were determined. Bean samples were obtained from farmers at initial moisture content of about 15%. Some of the beans were dried to moisture content of 12 and 9%. Samples at 15%, 12% and 9% were stored in plastic buckets, earthenware, polypropylene and sisal bags at ambient temperature (22-28 oC). Samples were drawn at monthly intervals and analyzed for cooking time, lignin, acid detergent fiber, calcium and magnesium content. Extent of HTC defect was found to be in the order K131> K132> NABE11> NABE4. The higher the moisture content the greater the extent of HTC development. HTC was found to be associated with increase in lignin content (r2 = 0.72). A significant increase in acid detergent fibre (ADF) was observed in samples stored in all the 4 storage containers. The increase was highest for beans stored in polypropylene bags and plastic buckets while beans stored in the sisal bags and earthenware had the least increase. Storage in sisal bags (25ºC, RH 74%) which allowed equilibration of the temperature and relative humidity with that of the environment controlled HTC defect development more than other methods; pot (22ºC, RH 93%) polypropylene bags (25.8ºC, RH 80%) and plastic bucket (27.9ºC, RH 84%). Based on the results of this study drying beans to lower moisture content and prevention of heat build up during storage, are recommended as strategies to control HTC development. Keywords: Hard –to-cook, Legumes, Grain storage, Lignification. AJFAND Vol. 8 (3) 2008: pp. 333-348

A comparison between the properties of seed, starch, flour and protein separated from chemically hardened and normal kidney beans

AbstractThe physicochemical, functional and thermal properties of starch, flour and protein isolates obtained from chemically hardened kidney beans were evaluated. A rapid chemical hardening procedure (soaking in acetate buffer, pH = 4.0, 37 °C, 6 h) was used to produce hardened kidney beans. Chemical hardening altered physicochemical, cooking, hydrating and textural properties of beans to a significant level (P &lt; 0.05). Soaked and cooked chemically hardened beans had a higher value for different textural parameters than their normal counterparts. Chemical hardening increased cooking time (from 49 to 123 min) of beans and decreased swelling power and solubility of starch. The turbidity value of gelatinized starch suspensions from chemically hardened beans was significantly lower than that from normal beans. Chemical hardening of beans caused significant increase in transition temperatures (To, Tp, Tc) and enthalpy of gelatinization (ΔHgel) of both starch and flour. Chemically hardened bean starch showed significantly higher pasting temperature (94.9 °C) as compared to normal bean starch (83.2 °C). Flour and protein isolate from chemically hardened beans showed significantly lower water absorption, oil absorption, foaming capacity and gelling ability than those from normal beans. The onset temperature (Tm), peak denaturation temperature (Td) and heat of transition or enthalpy (ΔH) of protein isolate from hardened and normal beans did not differ significantly. Copyright © 2007 Society of Chemical Industry

Microstructural changes of starch in cooked wheat grains as affected by cooking temperatures and times

The changes of starch microstructure in soft and hard wheat grains after cooking in a pressure cooker were investigated using a scanning electron microscope (SEM) and a light microscope (LM) in conjunction with image analysis. The conditions studied included variation of the cooking times (20–120 min) at the constant temperature (120 °C) and with variable temperatures (110–140 °C) for constant time (40 min). SEM images showed that steam induced changes in the intact starch granules of cooked wheat grains, with the microstructure becoming more in mud-like structure, with increased cooking time or temperature. The swelling and gelatinization of starch granules could contribute to this change. Suspensions of cooked wheat flour were selectively stained with iodine, for observation using the LM. The image analysis software was used for quantitative analysis of the images captured from the LM, providing both the number and area of the starch granules (determined from the dark-blue spots) per fixed image size. With increased cooking time or temperature, the number of starch granules decreased and the area increased as a result from the swelling and melting of starch granules. This study demonstrated the use of SEM and LM for the investigation of starch granules in cooked wheat grains without prior starch isolation.

Effects of endosperm texture and cooking conditions on the in vitro starch digestibility of sorghum and maize flours

The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant ( k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of M r>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour.

Effect of Cooking Time, Steeping and Lime Concentration on Starch Gelatinization of Corn During Nixtamalization

AbstractWhite dent corn was nixtamalized under different conditions to evaluate thermal properties using differential scanning calorimetry (DSC), swelling power and solubility. Cooking time was the factor that had the major influence on the behavior of the evaluated parameters as indicated by the analysis of variance. Onset and peak temperatures of gelatinization increased with increasing cooking time while gelatinization enthalpies decreased, indicating that more starch granules were gelatinized. A decrease in the swelling power was also observed at increasing cooking times, but solubility was significantly inhibited only if steeping was allowed. Considering these results, it was assumed that amylose‐lipid complexes are being formed during cooking and reorganized during steeping. X‐ray studies confirmed the presence of amylose‐lipid complexes. Steeping also caused an increment in the peak temperature that seemed to support the hypothesis of recrystallization or annealing occurring during this nixtamalization step. Temperature ranges indicated that in general, lime acted as a factor for structural disorganization.

Alkaline sulfite/anthraquinone pulping of pine wood chips biotreated with Ceriporiopsis subvermispora

AbstractPine wood chips were treated for 30 days with Cemporiopsis subvermispora in 20 dm3 bioreactors. A typical selective biodelignification was observed. The biotreated wood chips and undecayed controls were subjected to modified alkaline sulfite/anthraquinone (ASA) cooking at 170 °C or 175 °C applying varying cooking times ranging from 30 to 270 min. In all cases, the residual lignin content of the pulps prepared from biologically pretreated wood chips was lower than that of the control pulp. With increasing cooking time, however, the differences in kappa number became smaller. Wood chips cooked for a short time required mechanical refining for fiber liberation. A disk‐refining step resulted in pulps with low reject content (0.4%) and high screened yield (56–60%). In this case, the use of biotreated wood chips provided pulps with significantly lower kappa numbers than for the control pulp (71 and 83, respectively). The pulp from biologically pretreated wood fibrillated rapidly, reaching 20° SR in only 38 min beating time in a Jokro mill, while the control pulp required 56 min to reach the same beating degree. Although easier to beat, the biopretreated pulps showed tensile and burst indices similar to those of the control samples. However, their tear indices were always lower. Easier delignification after wood biotreatment was not observed for the reactions performed at long cooking times. Oxygen delignification of biotreated and conventional ASA pulps with low kappa numbers reduced kappa number and improved brightness considerably with the biotreated pulps being favored by a better preservation of viscosity. Copyright © 2004 Society of Chemical Industry

Effect of storage on the selected properties of macaroni enriched with wheat germ

Macaroni was produced from semolina blended with 15% raw and microwaved wheat germ and stored at room temperature. Samples were analyzed for sensory attributes, cooking quality, color and compressibility during storage. Effect of cooking time (10, 20, 30 min) on cooking quality of macaroni was also studied. Results indicated that protein content of macaroni increased up to 17% with wheat germ addition, as expected. Addition of raw and microwaved wheat germ increased cooking losses and volume of cooked macaroni but reduced weight after cooking. Increasing cooking time significantly increased cooked weight and cooking loss, as well as volume, acidity and compressibility of macaroni samples. However, after 20 min cooking, a decrease in volume of cooked macaroni was observed. No significant effect of storing was found on the measured parameters except acidity. Acidity of enriched samples showed a significant increase during storage. Supplementing durum semolina with raw and microwaved wheat germ provided macaroni with similar results to durum macaroni in compressibility. Enriched macaroni samples were more red and less yellow in color compared to the control sample. In taste panel evaluation, panelists showed the same preference in texture and overall score for both types of macaroni.

CHANGES IN COOKING AND TEXTURAL PROPERTIES OF SPAGHETTI COOKED WITH DIFFERENT LEVELS OF SALT IN THE COOKING WATER

The effect of cooking water on textural and cooking properties of spaghetti was examined using four different salt concentrations 0, 1, 2, 3 and 4% in the cooking water and two types of spaghetti. Brand A was normal durum wheat spaghetti and brand B was spaghetti enriched with bran. Regardless of the cooking water used, brand B was harder, less sticky than brand A and it absorbed less water. Brand A required less cooking time. As salt concentration increased cooking time and hardness scores increased. Adhesiveness values were highest at the early stages of cooking and declined as cooking time increased.

Effect of high water-holding capacity on the formation of heterocyclic amines in fried beefburgers.

Mutagenic/carcinogenic heterocyclic amines (HAs) are formed in the crust during the cooking of meat. The influence of cooking loss, time, and temperature on the formation of HAs was investigated in fried beefburgers. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were identified in all samples. The amounts of PhIP, MeIQx, and 4,8-DiMeIQx increased with increasing cooking time, and this effect was significant for all three HAs. The pan temperature had a significant effect on the formation of PhIP and 4,8-DiMeIQx. The addition of NaCl/sodium tripolyphosphate to the beefburgers reduced the cooking loss and decreased the formation of PhIP, MeIQx, and 4,8-DiMeIQx. This decrease was significant for MeIQx and 4,8-DiMeIQx. The results clearly show that it is possible to modify cooking practices to minimize the formation of HAs.

Kinetic characterization of cooking-induced changes in crambe seed prepared for expelling

Expellers offer a viable means for extracting oil from crambe seed ( Crambe abyssinica) and other niche oilseeds. Oilseeds are often cooked before expelling; however, little is known about the effects of cooking on the seed. Crambe seed (9% moisture) was cooked at exactly 80–112 °C for 5–20 min, using a bench-scale steam cooker developed for this purpose. Seed myrosinase activity decreased to below detection under the more intense conditions. Soluble protein content and light absorbance (280 and 420 nm) of aqueous seed extracts decreased with increased cooking time and temperature, in accordance with a first-order kinetic model. The D 0 and z-values for absorbance at 280 nm were 12.7 min and 36.6 °C, respectively. Measurement of absorbance at 280 nm is a simple, rapid analytical method that may be useful to tune the cooking conditions for improved expeller performance.

Cooking indices to predict screw‐press performance for crambe seed

AbstractScrew presses offer one means for extracting oil from crambe seed. Crambe seed was steam‐cooked at 80 to 112°C for 5 to 20 min, dried to 6% (wet basis), and screw‐pressed. Meal residual oil decreased with increased cooking time and temperature to a minimum at 10 to 15 min and 100°C (8.5 to 8.9% oil vs. 11 to 12% in uncooked or lightly cooked seed). More intense cooking increased residual oil to a high of 16% at 20 min and 112°C. The degree of cooking was quantified using indices based on light absorbance at 280 nm (A280 index, a measure of soluble protein) and myrosinase activity for aqueous seed extracts. Regression analysis showed that oil recovery, meal residual oil, and the A280 index were significantly correlated with cooking time and temperature. A plot of residual oil vs. the A280 index showed that this index helps discriminate between under‐, over‐, and optimally cooked seed. The myrosinase index helped identify undercooked samples but was unable to identify overcooked samples. The optimal A280 index values from this bench‐scale study may not be the same in full‐scale processes, but this approach can be adapted for tuning such processes.

STUDY of the POSSIBLE FORMATION of CALCIUM CROSS-LINKS IN LIME TREATED ("NIXTAMALIZED") CORN

The possible formation of calcium cross-links in lime-cooked (“nixtanalized”) corn was investigated. A 23 factorial design was utilized, with the following independent variables: lime (calcium hydroxide) dose, 1 and 3%, based on dry corn weight; cooking time, 1 and 2 h; and postcooldng holding time, 0 and 18 h. All samples were rinsed, air-dried, and ground in a hammer mill with a 40-mesh screen, and the corresponding viscoamylograms obtained. an untreated and milled (40 mesh) raw corn sample was used as control. Dependent variables were viscosities corresponding to attainment of maximum and minimum temperatures (95 and 50C) and end of holding periods at the same temperatures. Viscosities increased with increasing lime dose, decreased with increasing cooking time and were unaffected by holding time. These observations suggested that calcium cross-links were probably formed, and that degree of cross-linking increased with increasing lime dose (1 to 3%), and also with increasing cooking time (1 to 2 h).

Pasta‐Like Product from Pea Flour by Twin‐Screw Extrusion

ABSTRACTThe effects of extrusion parameters on the characteristics of a pasta‐like product were investigated. Increasing moisture content of the dough decreased brightness, bulk density, cooking loss and stickiness, but increased cooking time and firmness. Raising the barrel temperature increased cooking time, firmness and stickiness, but brightness, bulk density and cooking loss decreased. Increasing the screw speed increased cooking time, cooking loss, firmness and stickiness, but decreased brightness and bulk density. The product exhibited superior integrity, flavor, and texture after cooking, and less change after overcooking, compared to pasta‐like products prepared from pea flour using a conventional pasta extruder.