Improving the quality of bean dregs by physical methods during its use in bakery technology

Abstract

The dissertation is devoted to the scientific substantiation and development of technologies for improving the quality of bean dregs by physical methods during its use in bakery technology. It is established that the creation of new technologies of combined food can solve the problem of the lack of SDF, and improve the quality and functional characteristics of bean dregs. In addition, it provides better quality for the production of bean dregs biscuit. Combination of ultrafine grinding with high pressure, microwave and high-temperature cooking is a promising direction in the creation of processing the bean dregs due to mutual influence between physical technology is combined with each other, so that the nutrients in bean dregs are transformed. The purpose of the dissertation is scientific substantiation and development of technologies for improving the quality of leguminous waste when using physical methods in baking technologies. The object of the study is the quality of leguminous waste processed by physical methods. The subject of the study is the physicochemical properties of leguminous waste processed by physical methods; physico-chemical properties of dough and cookies made using bean waste; their technological, rheological and organoleptic properties; parameters of the processing of leguminous residues by physical methods. The relevance and feasibility of using ultrafine grinding combined with high pressure, microwave and high-temperature cooking for a good source of soluble dietary fiber for functional compositions and nutritional quality of bean dregs has been proved. The compositions, characteristics and physicochemical property of Physical single technology and combination technology for the treatment of bean dregs are investigated. In physical single technology and combination technology, the dependences of changes in the parameters of the SDF, protein, mineral content, particle size, scanning electron microscopy (SEM), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), trypsin inhibitors, water solubility, fat adsorption capacity, cationic adsorption capacity, chrominance and whiteness of bean dregs, and water relaxation properties, viscosity, stability, dynamic rheological properties of bean dreg slurry are determined. We obtained describing the processes of changing parameters. The resulting can be used for selecting optimum combination technology and for rich SDF in functional biscuit in the production of bean dregs. Several physical techniques were applied to increase the SDF content of bean dregs in this work, the optimum conditions for improving SDF of soybean dregs were determined by single factor test. It was found that the SDF contents in bean dregs treated with ultrafine grinding (U), high pressure (HP), microwave (M), high temperature cooking (HTC) and their combination techniques (UHP, U-M and U- HTC) were 15.15 ± 0.12%, 10.40 ± 0.19%, 13.84 ± 0.13%, 13.87 ± 0.13%, 18.86 ± 0.11%, 19.23 ± 0.19%, and 16.89 ± 0.13%, respectively, much higher than that of the control sample, which was only 1.63 ± 0.2%. It has been proved that the bean dregs under physical technology treatment is a good source of soluble dietary fiber, and the application of combined methods is the development trend. Technologies of increase the content of SDF of bean dregs have been developed. The rational values of individual parameters and modes of technological schemes of these technologies are determined. The protein content of bean dregs was analyzed as described in the AOAC reference method. It was found that the single technical treatments, the protein content in bean dregs after U, HP, M and HTC treatments decreased from 23.46% to 11.96%, 16.30%, 12.85% and 13.09%, respectively. The protein contents in bean dregs were further reduced after combination treatments, especially U-HP treatment. It was proved – protein content in bean dregs decreased greatly after physical technology treatment with either single techniques or with combined techniques. As expected, some parameters were decreased significantly (p < 0.05) by different physical technologies as compared with those of the control, the combined treatment had the greatest effect on the particles of bean dregs. The particle size of bean dregs was smallest (69.52 μm) after U treatment, among all single technology treatments. However, among all combined technology treatments was smallest by U- HP (27.43 μm) treatment. It has been proved that combination treatments were further improved roughness of bean dregs. The mineral content of bean dregs was determined by inductively coupled plasma-atomic emission spectrometry. U-HP combination increased the contents of Ca, Na, Fe, Ti and Sr. and the combination of U-M and U-HTC treatments greatly increased the K and Ca contents. In single treatment, the highest contents Se and Sn were found in the samples by U treatment, however, M and HTC techniques reduced the contents of K, Ca, Mg and Zn element in single treatment. The combination treatments help the exposure of mineral elements in the samples were confirmed. After various physical treatments, the microstructure of bean dregs SEM were consistent with the results of particle size distribution. The surfaces of treated bean dregs were rough, irregular and full of holes compared with control samples (had a loose sheet structure with many folds, and the fiber bundle exhibited an ordered structure). The bean dregs by U and combined treatments showed honeycomb structure and small particle distribution. It was proved – processing performances improved of bean dregs. SDS-PAGE was used to detect the molecular weight distribution of proteins. U treatment had no effect on the content of protein subunits in bean dregs. HP and U- HP treatments had some effect on the molecular weights of the protein. After the M and U-M treatments, the protein bands for molecular weights above 90 kD became lighter in color. After HTC and U-HTC treatment, the protein bands had disappeared completely. It has been proved that the single treatments M and HTC and the combined treatments U-M and U-HTC had great influence on the molecular weights of protein. It was experimentally established that the effects of non-heating treatments (U, HP and U-HP) on the reduction of trypsin inhibitor content were much inferior to those involving heat treatment. HTC and U-HTC had prominent effects on inhibiting trypsin inhibitor activity, which were decreased from 7365 TIU/g to 1210 and 96 TIU/g, respectively. This indicated that heat treatment effectively reduced trypsin inhibitor activity. Research was carried out on changes in the water solubility, swelling capacity, fat absorption capacity and cationic adsorption capacity of processing performance of bean dregs. The results showed that both single treatments and combination treatments significantly increased the water solubility of bean dregs, and the solubility of bean dregs from the combined treatment were higher than those from the single treatment. However, the swelling capacity and fat adsorption capacities of bean dregs were decreased, and the single treatment were higher than those from the combined. The adsorption capacity of bean dregs showed that the bean dregs treated by the combination technology contained smaller particles, so they had stronger cationic absorption capacity. It has been confirmed that the introduction of the bean dreg powder into the intestinal tract is beneficial to absorb Na+ and discharge it from the body, thereby reducing the incidence of cardiovascular and other diseases, processing performance of bean dregs enriches their application in foods and improves their physiological function. Water relaxation properties in bean dregs treated by different physical technologies were determined by low field nuclear magnetic resonance (LF-NMR) After the HTC, U-HP, U-M and U-HTC treatments, the proportion of bound water of bean dregs increased and the proportion of immobile water decreased after rehydration. And the peak area of the bean dregs treated with HP and HTC increased slightly. In addition, the free water content (A24) is positively correlated with the water content (W %) of dried bean dregs. This technique can effectively and nondestructively determine the change of water relaxation in samples. Bean dreg slurry was prepared for determination of viscosity with a rapid viscosity analyzer. The viscosity of bean dregs slurry was decreased after different treatment, especially the combined treatment. However, only M treatment increased the viscosity of bean dregs slurry, compared to the control samples. This indicated that the viscosity of bean dregs under the combination technology was low. Different treatments could obviously effect of different treatments on the stability of bean dreg slurry. After standing for 48 h and 72 h, microbial infection occurred in tubes M, HTC and U-HTC treatment, and the supernatant volume decreased or disappeared. However, the bean dregs under HP and U-HP treatment were the most stable, with little change in supernatant volume after 72 h. After standing for a week, there was an odor in every tube, indicating that each tube was corrupted. This indicated that combination technology that could be useful in the food industry to prolong the shelf life of foods. The dynamic rheological properties of the bean dregs slurry were determined by a rotary rheometer. In comparison, the G′ and G′′ of the bean dregs treated with U and HP were lower than those of M and control samples, and higher than those of the samples by HTC and all combined treatments. However, except the M treatment, HTC and all the combined treatments (U-HP, UM and U-HTC) were at a lower level, and the change trend of the loss factor (tan δ) and G′′ have the same trend. This indicated that the combined treatment could reduce the granularity of bean dreg fiber, but its viscosity and elasticity did not increase. The bean dregs treated by thermal treatments (M, HTC, U-M, and U-HTC) had lower values of L*. Except for the U-HP treatment, the a* and b* values of the other treatments were significantly greater than those of the control group. The HP, M, HTC and U-HTC treatments resulted in higher values in the ΔE (total color difference) of the samples. The whiteness index (WI) was also significantly affected by different physical treatments. These results demonstrated that different physical treatments had definite effects on the chrominance of bean dregs. It is established that the introduction of the proposed combined technologies to treat bean dregs for the production of biscuits is economically feasible. In this study, U-M combined technology was used to prepare bean dreg powder for crisp biscuits and hard biscuits. The strength of flour used in making crisp biscuits (low gluten flour) and hard biscuits (medium gluten flour) is different, but has a consistent trend on the viscosity of paste. It was experimentally established that the addition of bean dregs greatly reduced the viscosity of paste, and all the indexes showed a downward trend (peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity). The experimental results show, that the add a certain amount of bean dregs powder can effectively improve the gelatinizing characteristics of flour and increase the crispness of biscuits. Measurement of crisp biscuits dough texture in the texture analyzer showed that the hardness value increased when bean dregs content in the biscuit formulation was increased. The hardness was 5019.95±114.01 N when the bean dregs addition level of 15%, which was 54.78% higher than the control. However, above 20% of the bean dregs the dough hardness decreases. It can be explained that the chewiness of biscuits was positively correlated with hardness and gumminess. With the increase of the amount of bean dregs powder decreased L* and increased a* crisp biscuits values, indicating more dark and yellowish, b* values decreased added bean dregs at 5-25%. Concerning the crisp biscuits color, it became darker (lower L*), more reddish (higher a* values), and less yellowish (lower b* values) when bean dregs was added at 15-25%. The determination trend was similar to the crisp dough results. It was proved – the color of a baked good can be attributed to both the individual ingredients of the item and the color developed from ingredient interactions. The hardness of crisp biscuits increased gradually with the increase of bean dregs. When the bean dregs powder was added at 15%, the hardness reached the maximum of 2328.49 N. When the bean dregs powder was added at 20%, the hardness of biscuit showed a downward trend. The hardness, gumminess and chewiness are positively correlated. The determination trend was similar to the crisp dough results. The addition of bean dregs powder can effectively improve the gelatinizing characteristics of flour and increase the crispness of biscuits. With the increase of the proportion of soybean residue powder, the internal structure of the biscuit changes greatly, the gap gradually becomes larger, and the surface becomes rough from fine. When the addition of soy powder exceeds 20%, the butter in the dough is unable to coat the starch particles, gluten proteins and fibers present in the flour, affecting the quality of the crisp biscuits. According to the characteristics of dough and the sensory evaluation of crisp biscuits, the maximum amount of bean dregs was 20%, which gave the biscuits a better taste. Through single factor and orthogonal test results the optimal formula of bean dregs crisp biscuits was obtained: 80 g low-gluten flour, 20 g bean dreg powder (after U-M treatment), 50 g butter, 20 g powdered sugar, 5 g corn starch, 20 g egg yolks, 1 g salt, 0.75 g baking powder, and baked at 175 ℃ for 11 min. The bean dregs crisp biscuits prepared by this processing technology got the crispy taste, golden color, and good bean fragrance. Sensory score of bean dregs crisp biscuits was 94 points, and hardness value was 1597.41 H. With the increase of bean dregs addition, gelatinization characteristics showed a significant downward (p < 0.05). The peak viscosity decreased by 22.37%, the trough viscosity decreased by 20.82%, and the final viscosity decreased by 20.22% compared with the control group. The reason may be that bean dregs have strong water absorption capacity and compete with starch for more water, resulting in starch can’t be fully gelatinized. In rheological analysis the bean dregs increased could viscosity and elasticity of hard dough. With the increase of bean dregs, the hardness was higher than that of the control. The highest hardness was 7464.53±219.99 N, when the bean dregs addition level of 12.5%, which was 86.27% higher than the control. This was probably due to fiber and protein of bean dregs compete with the flour for moisture, in a way that promotes gluten production until it suppresses the behavior causing an increase in the hardness of the dough. The hardness, gumminess and chewiness are positively correlated. The determination trend was similar to the hard dough results. With the increase of the amount of bean dregs, the reduced L* (became darker) and increased a* (more reddish) of hard biscuits values, which changes from golden brown to caramel color. The cake crust temperature exceeded 150 ºC during baking, and thus Maillard and sugar caramelization reactions take place and are responsible for the final crust color. The parameters showed increases in the hardness, cohesiveness, gumminess, chewiness of the biscuits compared with control. The hardness was 4698.98±97.71 N when the bean dregs addition level of 12.5%, which was 53.75% higher than the control. The gumminess values of the biscuit with bean dregs were significantly higher than that of the control and significantly (P < 0.05). However, the gumminess values of the biscuit with bean dregs additions of 2.5 % were not significantly different from additions of 5% (P > 0.05). The chewiness was 473.57±131.04 when the bean dregs addition level of 12.5%, which was 93.14% higher than the control. The SEM results further confirmed that bean dregs powder had a certain effect on the biscuit hardness, which was consistent with the TPA results of biscuit texture. According to the characteristics of dough and the sensory evaluation of hard biscuits, the maximum amount of bean dregs was 10%, which gave the biscuits a better taste. Through single factor and orthogonal test results the optimal formula of bean dregs hard biscuits was obtained: 90 g wheat flour, 10 g bean dreg powder (after U- M treatment), 30 mL water, 25 g sugar powder, 5 g starch, 1 g baking powder and 0.5 g salt, then add 20 g egg yolk, 5 g soybean oil, surface fire temperature at 195 ℃ for 8 min. Sensory score of bean dregs hard biscuits was 88 points, and hardness value was 4344.95 H. A set of measures has been carried out to put the results of the study into practice. It is established that the introduction of the formulation process for the production of biscuits products is economically feasible. The new technology will be applied to the food industry.