Two-stage preparation of highly mesoporous carbon for super-adsorption of paracetamol and tetracycline in water: Important contribution of pore filling and π-π interaction.

This study aimed to develop an extremely highly porous activated carbon derived from soybean curd residues (SCB-AC) through two-step pyrolyzing coupled with KOH activating process and then apply it for removing paracetamol (PRC) and tetracycline (TCH) from water. The optimal conditions for chemical activation were 800 °C and the ratio of KOH to material (4/1; wt./wt.). SCB-AC adsorbents (before and after adsorption) were characterized by Brunauer-Emmet-Teller (BET) analyser, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, and Raman spectroscopy. Adsorption kinetics, isotherm, and thermodynamics were concluded under batch experiments. The effects of pH (2-10) and NaCl (0-1 M) on adsorption processes were investigated. Reusable properties of laden SCB-AC were evaluated by studying desorption and cycles of adsorption/desorption. Results indicated that SCB-AC exhibited a large specific surface area (3306 m2/g) and high total pore volume (2.307 cm3/g), with mesoporous volume accounting for 86.9%. Its porosity characteristics (average pore width: 2.725 nm) are very appropriate for adsorbing two pharmaceuticals through pore-filling mechanism. Adsorption processes were less affected by the parameters: pH, NaCl, and water matrixes. The kinetics for adsorbing PRC reached a faster equilibrium than that for TCH. The Langmuir maximum adsorption capacity of SCB-AC (pHeq 7.0 and 25 °C) was 1235 mg/g (for adsorbing TCH) and 646 mg/g (PRC). Pore filling (confirmed by BET analyser) and π-π interaction (confirmed by FTIR and Raman spectroscopy) were dominant adsorption mechanisms. Those mechanisms were physisorption (ΔH° = 13.71 and -21.04 kJ/mol for adsorbing TCH and PRC, respectively). SCB-AC can serve as an outstanding material for removing pharmaceuticals from water.

Food waste and soybean curd residue composting by black soldier fly.

This study attempted to manage the food waste and soybean curd residue generated in Taiwan's National Ilan University by black soldier fly-aided co-composting. The food waste and soybean curd residue were co-composted with rice husk as a bulking agent in 4:1 ratio and 0.42 mg BSF/g waste. The higher organic matter degradation of 31.9% was found in Container B (black soldier flies aided food waste and rice husk co-composting) with a rate constant of 0.14 d-1. In Container D (black soldier flies aided soybean curd residue and rice husk co-composting), the organic matter degradation of 29.4% was found with a rate constant of 0.29 d-1. The matured compost of 6.02 kg was obtained from 20 kg of food waste, while 5.83 kg of matured compost was generated from 20 kg of soybean curd residue. The physico-chemical parameters of the final matured compost were in the favorable range of Taiwan's compost standards. The germination index was 188.6% and 194.78% in Containers B and D, respectively. The present study will expand the application of BSF at the institutional level which prove to be a feasible solution for rapid, clean, and efficient composting of post-consumer food wastes.

Inactivation Kinetics and Membrane Potential of Pathogens in Soybean Curd Subjected to Pulsed Ohmic Heating Depending on Applied Voltage and Duty Ratio.

The aim of this research was to investigate the efficacy of the duty ratio and applied voltage in the inactivation of pathogens in soybean curd by pulsed ohmic heating (POH). The heating rate of soybean curd increased rapidly as the applied voltage increased, although the duty ratio did not affect the temperature profile. We supported this result by verifying that electrical conductivity increased with the applied voltage. Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in soybean curd were significantly (P < 0.05) inactivated by more than 1 log unit at 80 Vrms (root mean square voltage). To elucidate the mechanism underlying these results, the membrane potential of the pathogens was examined using DiBAC4(3) [bis-(1,3-dibutylbarbituric acid)trimethine oxonol] on the basis of a previous study showing that the electric field generated by ohmic heating affected the membrane potential of cells. The values of DiBAC4(3) accumulation increased under increasing applied voltage, and they were significantly (P < 0.05) higher at 80 Vrms, while the duty ratio had no effect. In addition, morphological analysis via transmission electron microscopy showed that electroporation and expulsion of intracellular materials were predominant at 80 Vrms Moreover, electrode corrosion was overcome by the POH technique, and the textural and color properties of soybean curd were preserved. These results substantiate the idea that the applied voltage has a profound effect on the microbial inactivation of POH as a consequence of not only the thermal effect, but also the nonthermal effect, of the electric field, whereas the duty ratio does not have such an effect.IMPORTANCE High-water-activity food products, such as soybean curd, are vulnerable to microbial contamination, which causes fatal foodborne diseases and food spoilage. Inactivating microorganisms inside food is difficult because the transfer of thermal energy is slower inside than it is outside the food. POH is an adequate sterilization technique because of its rapid and uniform heating without causing electrode corrosion. To elucidate the electrical factors associated with POH performance in the inactivation of pathogens, the effects of the applied voltage and duty ratio on POH were investigated. In this study, we verified that a high applied voltage (80 Vrms) at a duty ratio of 0.1 caused thermal and nonthermal effects on pathogens that led to an approximately 4-log-unit reduction in a significantly short time. Therefore, the results of this research corroborate database predictions of the inactivation efficiency of POH based on pathogen control strategy modeling.

Valorisation of By-Products from Soybean (Glycine max (L.) Merr.) Processing.

In recent years, increased awareness of the health benefits associated with consuming soy-based foods, knowledge of milk-related allergies and a move towards more sustainable food production have led to an increase in the number of available soy-based products. The biggest producers in the world, the USA, South America and China, are from the Pacific region. This enormous production is accompanied by the accumulation of related by-products, in particular, a substance that is known as okara. Okara is a paste that is rich in fibre (50%), protein (25%), fat (10%), vitamins and trace elements. Its proper use would lead to economic advantages and a reduction in the potential for polluting the environment. Its high fibre content and low production costs mean that it could also be used as a dietary supplement to prevent diabetes, obesity and hyperlipidaemia. Chemical or enzymatic treatment, fermentation, extrusion, high pressure and micronisation can all increase the soluble fibre content, and thus improve nutritional quality and processing properties. However, the product also degrades rapidly due to its high moisture content (70-80%), which makes it difficult to handle and expensive to dry by conventional means. The aim of this paper is therefore to thoroughly study the existing literature on this subject in order to develop a general protocol for okara exploitation and valorisation. A cost/benefit analysis could drive the design of eco-friendly, sustainable protocols for the preparation of high-value nutritional products.

Palatability of black soldier fly larvae in valorizing mixed waste coconut endosperm and soybean curd residue into larval lipid and protein sources.

The black soldier fly larvae (BSFL) have been widely extolled for the application in managing various solid organic wastes. Owing to the saprophagous nature of BSFL, a rapid valorization of solid organic wastes can be accomplished with the simultaneous production of valuable biochemical compounds derived from larval biomass. In the present works, the mixed waste coconut endosperm (w-CE) and soybean curd residue (SC-r) substrates with increasing protein nutritional constituent were administered to BSFL. The correlations between protein from larval feed substrates and nutritional profiles of BSFL biomasses were ultimately unveiled. The protein from larval feed substrates could be increased by increasing of SC-r portion against w-CE. At the w-CE:SC-r ratio of 3:2, the highest larval total weight gained and growth rate were attained; indicating an optimum protein nutritional constituent in mixed organics (12.4%) that could enhance the BSFL palatability. Further increment of protein nutritional constituent in mixed organics was found acidifying the residual larval feed substrate progressively, undermining the growth of BSFL. By feeding the BSFL with optimum mixed organics, the maximum accumulations of larval lipid and protein could be achieved. Transesterification of extracted lipid had demonstrated high in monounsaturated fatty acids (73%) which was suitable for biodiesel. The BSFL palatability was finally confirmed from the bioconversion viewpoint of mixed organic wastes. Again, achieving the highest bioconversion efficiency of 14% into larval biomass after accounting the metabolic loss of 54%. Therefore, a total of 68% of mixed w-CE and SC-r could be successfully bioconverted.

Spoilage Bacteria Identification and Food Safety Risk Assessment of Whole Soybean Curd.

As a highly hydrated gel-type food, soybean curd is perishable and the development of spoilage bacteria has been described. Whole soybean curd (WSC), an innovative soy product retains the most nutrients in raw ingredients and exhibits more nutritive value compared with conventional soybean curd (CSC). However, the risk assessment of WSC is not well evaluated up to now. In this study, the same species of spoilage microorganism were separated from WSC and CSC. Two main spoilage strains were separated and identified as B. subtilis and B. cereus. The risk ranking scores of WSC was higher than that of CSC but still within medium risk range. In summary, we reported the presence of B. subtilis and B. cereus in WSC for the first time. Further, application of the risk ranger tool confirmed that the risk profile of WSC was medium and acceptable.

Shelf life prediction and food safety risk assessment of an innovative whole soybean curd based on predictive models.

The aim of the present study is to predict the shelf life and evaluate the risk profile of an innovative whole soybean curd (WSC). Two main spoilage strains were isolated from spoiled WSC and identified as B. subtilis and B. cereus. The origin analysis confirmed that B. subtilis and B. cereus originated from soybean materials and survived in soybean curd. For microbial contamination analysis, thermotolerant coliforms, E. coli and S. aureus were not detected in soybean curd. The predicted shelf life of WSC and okara-filtered curd that was stored at 10 °C were 141.95 h (5.91 d) and 206.25 h (8.59 d), respectively. Moreover, the models applied in this study exhibited great fitting goodness and the predicted growth parameters were fail-safe. To conclude, introduction of okara into soybean curd reinforced the initial contamination level but didn't significantly increase the risk profile of WSC.

Application of transglutaminase for quality improvement of whole soybean curd.

To improve the quality of whole soybean curd (WSC), effects of compound coagulants consisting of calcium chloride (CaCl2) and transglutaminase (TGase) were investigated. The results showed that TGase modified the water distribution and reduced the cooking loss of WSC, accompanying with increased water holding capacity. The bloom value of WSC was upgraded as the TGase concentration increased. Although certain sensory parameters showed different scores in groups, the overall acceptability of 1500 ppm group was the highest. TPA test suggested that hardness, springiness and chewiness were promoted by TGase significantly. Smooth appearance of WSC was observed, resulting from the transformation of microstructure. Protein subunits of 7Sα', 7Sα, 7Sß, 11SA3, 11S acidic, and 11S basic proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, band intensity of protein subunits declined at storage and cooking phase, indicating that crosslinking of proteins was still in progress. In conclusion, the addition of TGase improved the quality of CaCl2-induced WSC and could be used to facilitate the production of this new type of soybean product.

Application of the ideal profile method to identify an ideal sufu for nonregular consumers.

BACKGROUND: Sufu is a fermented soybean food with unique odor, flavor, and texture, which might not be appreciated by nonregular consumers. To identify the attributes that nonregular consumers appreciated, 12 commercial products bought from a Hong Kong market were tested by 113 consumers according to the ideal profile method (IPM), and rated on 22 attributes. RESULTS: Data provided from nonregular consumers were consistent at both panel and consumer levels. The predicted ideal profile received a higher hedonic score (7.0) than the tested products (6.0). Compared with commercial samples, the ideal sufu has low intensity in the attributes of fermented (aroma and flavor), moldy (aroma), and hard (texture), but high intensity in the soybean-like (aroma and flavor) and sesame oil-like (aroma and flavor) attributes. CONCLUSION: IPM could be used as an alternative approach to collect sensory profiles and preference data directly from consumers for product characterization. It could also be applied to identify the attributes that nonregular consumers appreciated. © 2018 Society of Chemical Industry.

Changes in volatile profile of soybean residue (okara) upon solid-state fermentation by yeasts.

BACKGROUND: Soybean residue (okara), a by-product of soymilk, is produced in large volumes by the soy food industry and is often discarded due to its undesirable flavour. As it contains a considerable amount of protein and fats, biotransformation of okara to improve its flavour presents an opportunity for alternative utilisation. This paper evaluated 10 yeasts in the solid-state fermentation of okara based on their volatile profiles as analysed with HS-SPME GC-MS/FID. Four 'dairy yeasts' (Geotrichum candidum, Yarrowia lipolytica, Debaryomyces hansenii and Kluyveromyces lactis) and six 'wine yeasts' (Saccharomyces cerevisiae, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia kluyveri, Torulaspora delbrueckii, and Williopsis saturnus) were studied. RESULTS: The main off-odourants in okara, hexanal and trans-2-hexenal, significantly decreased after fermentation due to their bioconversion into methyl ketones and/or esters. The okara fermented by dairy yeasts contained greater proportions of methyl ketones, while that by wine yeasts contained more ethyl and acetyl esters. Notably, the okara fermented by W. saturnus contained 13 esters and the total GC-FID peak area of esters was about 380 times that in fresh okara, leading to a perceptible fruity note. CONCLUSION: Okara can be exploited as an inexpensive substrate for bioflavour extraction and/or a more pleasant food ingredient via yeast fermentation. © 2016 Society of Chemical Industry.