Starch affecting anti-staling agents and their function in freestanding and pan-baked bread

Anti-staling agents with different mechanisms were added to a normal white wheat bread to investigate the relation between bread staling, amylopectin retrogradation and water-related properties (i.e. water content and distribution between crumb and crust). Bread was baked both as pan-baked and freestanding loaves. The anti-staling agents maltogenic α-amylase, distilled monoglyceride and lipase had a direct influence on starch retrogradation, whereas gluten and waxy wheat flour diluted the amylopectin content or changed the ratio between amylose and amylopectin. The degree of staling was measured as the firmness and springiness, together with two new methods, crumbliness and cutability. In addition, the degrees of amylopectin retrogradation and amylose–lipid complex formation were analyzed by differential scanning calorimetry, and the water content, water loss and water migration were measured. The addition of α-amylase improved most staling parameters, although the changes were not as large as expected. Furthermore, monoglyceride and lipase increased the formation of amylose–lipid complexes, but only lipase gave better results regarding the specific volume and firmness. Increased amylose–lipid complex formation was seen to increase water migration from crumb to crust. Adding 10% waxy wheat flour appeared to lead to a slight overall improvement i.e. lower water migration and better cutability. Adding gluten or 3% waxy wheat flour only improved the specific volume. The method of baking the loaves, i.e. freestanding or pan-baked, had a greater influence than the anti-staling agents, which shows that bread quality is not always improved by starch affecting anti-staling agents without process changes.     

Improvement of resistant starch content and baking quality of cross-linked soft rice flour

Food Science and Biotechnology - To increase resistant starch (RS) content of rice flour, soft and normal rice flours were cross-linked with different flour concentrations (40, 50%). RS contents,...     

Effect of chitosan on physical and chemical processes during bread baking and staling

The objective of this research was to investigate the effect of chitosan on the interaction of water with bread ingredients and on the rate of staling. The changes in freezable bound water and total water contents in bread crumb were assessed by differential scanning calorimetry from water melting and evaporation endothermic peak areas. It was found that freezable water content and total water content in bread crumb decrease during staling more rapidly in the presence of chitosan. The weak interaction of freezable water with protein and starch polymeric chains in bread crumb becomes stronger, but the interaction of nonfreezable bound water with protein and starch molecules in bread crumb becomes weaker in the course of staling during bread storage. Two stages of bread crumb staling were indicated. Chitosan increases the rate of bread staling during both stages. It was suggested that during bread staling chitosan increases water migration rate from crumb to crust, prevents amylose-lipid complexation, and increases dehydration rate both for starch and gluten.     

Effect of crust temperature and water content on acrylamide formation during baking of white bread: Steam and falling temperature baking

The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking.     

Evaluation of four types of resistant starch in muffin baking performance and relationship with batter rheology

The influence of wheat flour partial replacement with different types of resistant starch (RS) in muffin batter rheological properties and in baked muffin height, volume and number of air bubbles was investigated. The type of RS affected the above-described properties differently. In comparison to the control batter (without RS), replacement with RS type 3 (Novelose 330 and C*Actistar) increased viscosity and viscoelasticity, at both 20 and 80 °C. On the contrary, RS type 2 (Hi-maize 260 and Novelose 240) decreased them. These differences in viscosity and viscoelasticity were related to different baking performance. The RS3 type muffins had higher height, volume and number of air bubbles than the RS2 type muffins. An increase in viscosity and elasticity of the raw batter and during the heating process favours bubble retention and stability, thus favours baking performance. However, despite the improvement provided by the RS type 3, the baking performance was still lower than in the control muffins. One feature that may contribute to the baking differences is the delay in all the RS batters in the starch gelatinization temperature.     

Effect of leavening agents and sugars on the formation of hydroxymethylfurfural in cookies during baking

The effects of recipe compositions in terms of leavening agent (ammonium and sodium bicarbonates) and sugars (sucrose and glucose), and baking conditions (temperature and time) on HMF formation in cookies were studied. Five recipes were prepared by varying the types of leavening agent and sugar. The cookies were baked at different temperatures (180, 200, 210 and 220 °C) for different time (10, 15, 20 and 25 min) to monitor physical and chemical changes in cookie composition in terms of water activity, pH, surface browning, sugar decomposition, and hydroxymethylfurfural (HMF) formation. Decreasing moisture to a level under a water activity of 0.4 appeared as the critical point in baking where the rate of HMF formation drastically increased after this point. After this stage, sucrose decomposed very rapidly if ammonium bicarbonate was used as the leavening agent at temperatures greater than 200 °C. Replacing ammonium bicarbonate with sodium bicarbonate maintained pH of cookies ranging between 9.0 and 10.0 during baking, which limited the decomposition of sucrose.     

Rheological behaviors,structural properties and freeze–thaw stability of normal and waxy genotypes of barley starch: a comparative study with mung bean,potato, and corn starches

The rheological behaviors, structural properties and freeze-thaw stability of starch isolated from Tetonia barley (Normal genotype, Reg. No. CV-334, PI 646199) and Transit barley (Waxy genotype, Reg. No. CV-348, PI 660128) were investigated, along with other common starch sources for comparison. Transit barley starch showed the highest loss tangents (tan δ) during a frequency sweep test, which suggested a predominance of elastic properties over viscous properties. However, the tan δ of Tetonia barley starch was similar to that of potato starch, which indicated more solidity in comparison to Transit barley starch. Transit barley starch had the highest gelatinization temperature and the lowest gelatinization enthalpy (P < 0.05). Moreover, Tetonia and Transit barley starches displayed weak diffraction peak intensities by X-ray diffraction analysis. Additionally, Transit barley starch showed the lowest % syneresis even when freeze–thawed up to five cycles (P < 0.05). However, Tetonia barley starch had the worst freeze–thaw stability (P < 0.05), which was verified via scanning electron microscopy analysis of freeze–thawed starch gels. The results of present study indicate that barley starch can be practically applied as a functional ingredient in some specialty starchy foods.     

Performance of a resistant starch rich ingredient in the baking and eating quality of short-dough biscuits

The effect of replacing part of the wheat flour with a resistant starch rich ingredient (RSRI) − a source of functional fibre with potential health benefits − was studied in short dough biscuits. A control with no replacement and 3 formulations in which 20, 40 and 60g of flour per 100 g were replaced by an RSRI (samples 20RSRI, 40RSRI and 60RSRI) were prepared. From a technological point of view, the RSRI level influenced the consistency of the raw dough and the ease of sheeting and cutting. Regarding the eating quality of the final product, addition of the RSRI increased the breaking strength and crumbliness and reduced the resistance to penetration. In the RSRI biscuits, both the surface and the crumb were paler. The sensory acceptance of the 20RSRI biscuits did not differ significantly from that of the control. 40RSRI reduced the acceptability of the colour, appearance and texture without altering the taste, sweetness and overall acceptance. Neither of these two levels significantly reduced the consumption intention. However, 60% flour replacement produced biscuits with lower sensory acceptability and a significant reduction in consumption intention. In general, the results could be interpreted in terms of the protein-diluting effect of the added ingredient and changes in the water content and water-retention capacity of flour mixtures containing RSRI. The present results proved that resistant starch rich ingredients (RSRI) have good potential for developing fibre-rich biscuits without changing their general features.     

Characterization and CFD modelling of air temperature and velocity profiles in an industrial biscuit baking tunnel oven

The industrial baking of cereal products is commonly performed in tunnel ovens, which give operators high flexibility for adjusting baking conditions to optimum values. This paper discusses the application of a CFD approach to predict the air temperature and velocity profiles inside the baking chamber of an industrial indirect gas-fired tunnel oven used for biscuit baking. We used two three-dimensional CFD models (one not covering the conveying band of biscuits and the other including it) to describe the complex air circulation resulting from the mechanisms of air input and exit at the ends of the oven and of air extraction through the different extraction points located along the oven length. Comparison of numerical results with experimental measurements shows a fairly close agreement in the qualitative prediction and a few inaccuracies in the quantitative prediction of the air temperature profiles within the baking chamber. Furthermore, the comparison also reveals great differences in the air velocity profiles.     

Variations in water absorption capacity and baking performance of barley varieties with different polysaccharide content and composition

In the present study, water absorption capacity (WAC) and the resulting baking performance of different barley-wheat flour blends were investigated by baking breads containing 40% barley flour. The different barley varieties varied in polysaccharide contents and composition. Knowledge about variations in WAC and its possible effects on the baking performance were gained by choosing a constant water addition. These variations were related to differences in chemical content and composition. Large variations in WAC were observed for the different barley-wheat mixtures. These variations further resulted in variations in weight, volume and form ratio of the breads. Thus, large individual differences in baking performance were observed and these differences related to differences in polysaccharide content and composition of the different barley flours. Total β-glucan content was the most important parameter for the baking performance and hence, the bread quality due to its significant contribution to the WAC.     

The influence of α-amylase-hydrolysed barley starch fractions on the viscosity of low and high purity barley β-glucan concentrates

Gelatinized barley starch was hydrolysed using porcine pancreatic α-amylase for various time intervals and the hydrolysate fractionated according to molecular weight distribution (low, medium and high) by gel permeation chromatography. The effects of hydrolysed starch fractions (2.5%, w/w) on the solution viscosity of low- (∼50%, w/w) and high- (∼88%, w/w) purity barley β-glucan (0.75%, w/w,) at different temperatures (20 and 37 °C) were determined and compared to that of a control. The results indicated that none of the hydrolysed starch fractions significantly influenced the solution viscosity of high purity β-glucan. However, addition of the medium molecular weight fraction to low purity β-glucan significantly increased its viscosity when determined at low shear rates (1.29–12.9 s⁻¹). Marginal changes in viscosity were observed at shear rates exceeding 12.9 s⁻¹. This study suggested that a non-β-glucan component in the low purity β-glucan concentrate probably influences the solution viscosity of “β-glucan–hydrolysed starch” blends.     

The behaviour and susceptibility to degradation of high and low molecular weight barley β-glucan in wheat bread during baking and in vitro digestion

The behaviour and susceptibility to degradation of a high molecular weight (HMW) and low molecular weight (LMW) barley β-glucan in white bread during manufacture and in vitro digestion were investigated. The incorporation of both HMW and LMW barley β-glucan resulted in stiffer dough, lowered loaf volume and height compared to the control. The HMW barley β-glucan caused the greatest loss of dough and bread quality. Breads with HMW and LMW barley β-glucan exhibited attenuated reducing sugars release (RSR) over a 300 min in vitro digestion compared to the control, with generally no difference between the breads. HMW barley β-glucan was degraded during bread manufacture; however, degradation of the LMW barley β-glucan was not apparent. An in vitro digestion did not result in any further degradation of the molecular weight (MW) of either barley β-glucan.     

Effect of low and high acetylation degree in the morphological, physicochemical and structural characteristics of barley starch

Barley starch was acetylated at two levels (low degree: LD (0.9), and high degree: HD (2.7)) substitution and the morphological, physicochemical and structural of the resultant acetylated barley starch were determined. The acetylated barley starches presented the signal at 1226 cm⁻¹ that corresponds to the C-O stretching of acetyl groups. The morphological study showed fusion of starch granules in the acetylated starch with HD. This effect was evident in the pasting test, because the viscoamylograph profile of HD starch showed the absence in peak viscosity, viscosity breakdown and viscosity setback. The peak gelatinization was similar for native and LD and decrease in the HD acetylated starch. The gelatinization enthalpy value showed difference among the samples, indicating that the loss of the ordered double helices more than the crystallinity loss was higher in the HD acetylated barley starch. In the retrogradation test, acetylation affected both retrogradation and enthalpy value, because acetylated barley starch with HD substitution at three storage days had 3.2 j/g and with LD 4.8 j/g. The molecular weight and z-average radius of gyration values decreased due to the acetylation process, indicating depolymerization of starch components as it was evidenced by the increase in short chains level in the acetylated samples.     

Microstructure and nutrient composition of hairless canary seed and its potential as a blending flour for food use

Canary seed is a true cereal with unique composition. The current study employed light and fluorescence microscopy to visualise starch, protein, phenolics and phytate in hairless canary seed (CDC Maria), a cultivar developed potentially for food use. Macronutrients, minerals and vitamins were evaluated in the developed cultivar and compared with a commercial hairy canary seed, cv. Keet. A control common wheat, cv. Katepwa, was grown adjacent to the canary seed varieties. The compositions of the two canary seed varieties were found to be similar with an average of 55.8 g/100 g of starch, 23.7% g/100 g of protein, 7.9% of crude fat, 7.3 g/100 g of total dietary fibre, 1.8 g/100 g of soluble sugar and 2.3 g/100 g of total ash in the whole grain. Regardless of the milling fraction (whole grain flour, white flour or bran), canary seed had more protein and crude fat and less starch, total dietary fibre and soluble sugar than had wheat. It also had higher concentrations of several minerals and vitamins than did wheat. The structure of the canary seed grain exhibited compound starch granules and protein bodies embedded in a protein matrix similar to that of the oat kernel. Baking tests showed that bread made with 100% hairless canary seed flour was significantly lower in loaf volume and crust and crumb colour than was wheat bread. However, bread with loaf volume, specific volume and crust colour comparable to those of the bread control was achieved by using up to 25% of hairless canary seed or 15% of roasted canary seed flour, thus demonstrating its potential for food applications.     

Effects of different components in skim milk on high-pressure-induced gelatinisation of waxy rice starch and normal rice starch

The gelatinisation of starch in skim milk required higher pressures than did the gelatinisation of starch in water. This study examined the effects of various milk components on the pressure-induced gelatinisation of waxy rice starch and normal rice starch, in order to understand the differences between the gelatinisation characteristics of starch in skim milk and starch in water. Gelatinisation was retarded in skim milk, which was attributed to the effects of soluble milk minerals and lactose. The presence of these components may reduce the plasticising ability of the suspension medium. Direct interactions between the milk components and starch molecules may also contribute to retarded gelatinisation. Milk proteins (casein and whey protein) did not affect the degree of pressure-induced gelatinisation at the concentrations of these components in skim milk, at 10% total solids.     

The ratio of B to C hordeins in barley as estimated by high performance liquid chromatography

The ratio of B to C hordeins was determined using high performance liquid chromatography (h.p.l.c.) for a range of spring barley cultivars and the values obtained varied from 1.79 for Kneifel to 4.15 for Goldmarker. Fine grinding of seed samples resulted in a significant increase in the quantity of protein solubilised but relatively little difference was observed in the B and C hordein ratio, which appeared to be independent of protein extraction efficiency. Increased nitrogen content significantly changed the ratio by increasing the proportion of C hordein. A highly significant correlation was found between the B and C hordein ratio and sample nitrogen content. Analysis of single seeds selected at random from within a single sample of Goldmarker revealed considerable variability in the B and C hordein ratios with values differing by over 2 units. Due to the sensitivity of the B to C hordein ratio to various environmental effects, it is unlikely that the ratio will be of great value as an unambiguous aid in the identification of barley cultivars.     

实验室检测工业大麻及相关产品的安全管理

随着工业大麻在医疗、保健食品、化妆品和纺织品等领域的应用价值的体现, 各国对大麻的限制政策逐渐放宽。我国现行法律法规仍旧有对大麻的运输、储藏和加工的限制, 因此实验室在进行大麻样品的检测时除了需要满足一般检测机构的基本要求外, 还必须符合一系列相关法规的规范要求。实验室在进行大麻样品的检测时也存在较大的安全风险, 所以对检测安全管理的规范性总结研究具有重要意义。本文对实验室检测工业大麻及相关产品的安全管理进行了讨论, 为实验室开展相关检测工作提供一定的参考。     

Differences in viscosity and textural properties of selected barley cultivars as influenced by pearling and cooking

Viscosity and texture are important attributes not only in determining quality of barley but also in delivering health benefits of barley products. The present study aimed at investigating viscosity and textural properties of nine barley cultivars selected for their compositional differences and economic importance to Canada. The cultivars were pearled to varying degrees to obtain whole grain and three pearled barley fractions named commercial, pot and white pearl. Increasing pearling time resulted in higher peak, trough, setback and final viscosity compared with whole grain flours. The hulless cultivars tested, tended to have lower trough, final and setback viscosities than the hulled ones. The waxy cultivars exhibited higher breakdown viscosities than normal cultivars. Viscosity at 37 °C of two cooked barley cultivars having extreme glycemic index (GI) values were significantly different. In other words, cooked Celebrity cultivar (low GI) had higher viscosity than AC Klink cultivar (high GI). Significant differences in maximum force and shearing work were also observed between cultivars. On the contrary to viscosity, both force and work decreased as pearling time increased. The study showed that some barley cultivars such as Celebrity fractions may hold a promise for the development of barley as a functional food ingredient or rice substitute.     

Influence of moisture content on the degradation of waxy and normal corn starches acid-treated in methanol

Waxy and normal corn starches with different moisture contents, 5.1-16.9% and 4.8-15.9%, respectively, were prepared and treated in methanol containing 0.36% HCl at 45 °C for 1 h. Recovery of all the treated starches was found to be above 90%. Peak viscosity, gelatinization temperature and enthalpy change of gelatinization of waxy and normal corn starches decreased after treatment and this decrement was found to be more in treated starches having lower initial moisture content. The weight-average degree of polymerization and chain length (CL) of waxy and normal corn starches decreased upon acid-methanol treatment. The decrement ratio of molecular weight of modified starches was found to be negatively correlated with the initial moisture content of the starches. The decrement ratio of normal corn starch was higher than waxy corn starch with similar moisture content of starch. The content and CL of long chain fraction of amylopectin for waxy corn starch slightly decreased after treatment, while no obvious trend was found among starches with different moisture contents. CL of amylose for acid-methanol-treated normal corn starch decreased and this change was found to be higher in starches with lower initial moisture contents. Results demonstrated that the initial moisture content of starch granules strongly influenced the functional properties and degradation of starch treated by acid in methanol.