Effects of atmospheric cold plasma and high-power sonication on rheological and gelling properties of mung bean protein dispersions.

The objective of this study was to evaluate the impact of high-power sonication (HPS) and atmospheric cold plasma (ACP) on gelling and rheological properties of mung bean protein dispersions. HPS at 250 J/mL for 2 min and ACP at 80 kV for 5 min were applied to different concentrations of mung bean protein isolate (MBPI). Control and HPS-treated MBPI dispersions showed a minimum gelling concentration (MGC) of 16% w/v, while ACP-treated dispersions started to gel at 14% w/v. Dynamic rheology of dispersions at 16 % concentrations showed that HPS and ACP treatments could reduce the initial gelling temperature to 52° and 65 °C, respectively, from 75 °C for no-treatment control. ACP-treated 16% protein dispersions showed a six-fold higher storage modulus (G') than the control. In addition, ACP treatment resulted in significantly more hydrophobic bonds (∼5.0 g/L) than control (∼1.4 g/L) and HPS-treated (∼1.1 g/L) MBPI gels; however, the net interaction of ionic, hydrogen, hydrophobic, and disulfide bonds was higher in HPS-treated MBPI gels. Thus, both ACP and HPS treatments altered the gelling characteristics of mung bean protein dispersions- ACP reduced MGC and improved firmness, whereas HPS improved the springiness, cohesiveness, gumminess, chewiness, and resilience of the gels.

Protein, lipid, and chitin fractions from insects: Method of extraction, functional properties, and potential applications.

Edible insects are accepted as food and feed ingredients in many parts of the world. Insects account for more than 80% of animal kingdom providing rich biodiversity of protein and lipid profiles compared to conventional livestock. Insect biomasses contain an average of 35-62% protein, 3-57% lipid, and 3-12% chitin, and their nutritional values are widely recognized due to their presence, including minerals, and vitamins. While whole insects are consumed as eggs, larvae, pupae, or adults, there has been a recent uptick in interest to use fractions, e.g., protein, lipid, and chitin, as food and feed ingredients. To utilize these fractions in various food and feed preparations, a deeper understanding of the physicochemical as well as functional properties of the ingredients is required, which are generally impacted by extraction and preparation processes. Thus, the methods of extraction/purification are important to preserve the quality and functional properties of these ingredients. This paper discusses the extraction methods for insect protein, lipid, and chitin, their functional properties, and potential applications in food and feed applications.

Evaluation of corn steep liquor as fermentation media for recombinant Lactococcus lactis producing antifreeze proteins.

BACKGROUND: Corn processing byproducts corn steep liquor (CSL), and thin stillage were evaluated as growth media for recombinant Lactococcus lactis modified to produce antifreeze proteins (AFPs) that could have important food and non-food applications. The AFP III sequence from ocean pout was cloned into a shuttle vector to make an expression vector that facilitated the production of recombinant AFP III in Lactococcus lactis. Light CSL from yellow dent corn and thin stillage from the industrial corn bioethanol process were optimized as fermentation media with a combination of the following additives and trace elements: disodium-ß-glycerophosphate (DG), tryptone (T), ascorbic acid (AA), iron (Fe), zinc (Zn), and magnesium (Mg). The growth of wild-type and recombinant Lactococcus lactis strains were compared over a 72 h period in 96-well plates and 250 mL shake flasks. RESULTS: The corn coproducts media consisting of 50% (v/v) light steep in water supplemented with DG-5 g L-1 , T-5 g L-1 , AA-0.5 g L-1 , and Zn-4 ppm resulted in best growth and was considered as the best-optimized media. The addition of additives and trace elements better supported the growth of both wild-type and recombinant Lactococcus lactis strains compared to control media without any additives. Respective fermentation supernatants were frozen to -20 °C, and the time to supercool and freeze was compared. A distinct supercooling effect was observed for the supernatants from recombinant strains thus, extending the time and temperature of supercooling and freezing. The maximum time of supercooling extended was 17.55 ± 4.45 min for thin stillage followed by M17 media (17.25 ± 4.45 min), Kent Corporation CSL (10.80 ± 2.12 min), and yellow dent CSL (6.9 ± 0.85 min) when fermented with recombinant Lactococcus lactis strains. CONCLUSION: The supplemented corn coproduct-based media enhanced the growth of both wild-type and recombinant Lactococcus lactis strains. These optimized media can replace or supplement more expensive media (e.g. M17), potentially reducing cost. The fermentation supernatants exhibited longer times to supercool, and freeze compared to control supernatants, indicating potential use as antifreeze compounds in frozen food and non-food applications. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fermentation performance and nutritional assessment of physically processed lentil and green pea flour.

BACKGROUND: Significant amounts of nutrients, including dietary fibers, proteins, minerals, and vitamins are present in legumes, but the presence of anti-nutritional factors (ANFs) like phytic acid, tannins, and enzyme inhibitors impact the consumption of legumes and nutrient availability. In this research, the effect of a physical process (sonication or precooking) and fermentation with Lactobacillus plantarum and Pediococcus acidilactici on the ANFs of some legumes was evaluated. RESULTS: Total phenolic content was significantly (P < 0.05) reduced for modified and fermented substrates compared with non-fermented controls. Trypsin inhibitory activity (TIA) was reduced significantly for all substrates except for unsonicated soybean and lentils fermented with L. plantarum and P. acidilactici. When physical processing was done, there was a decrease in TIA for all the substrate. Phytic acid content decreased for physically modified soybean and lentil but not significantly for green pea. Even though there was a decrease in ANFs, there was no significant change in in vitro protein digestibility for all substrates except for unsonicated L. plantarum fermented soybean flour and precooked L. plantarum fermented lentil. Similarly, there was a change in amino acid content when physically modified and fermented. CONCLUSION: Both modified and unmodified soybean flour, green pea flour, and lentil flour supported the growth of L. plantarum and P. acidilactici. The fermentation of this physically processed legume and pulse flours influenced the non-nutritive compounds, thereby potentially improving nutritional quality and usage. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ultrasound-assisted extraction and modification of plant-based proteins: Impact on physicochemical, functional, and nutritional properties.

Ultrasonication is a green technology that has recently received an enormous research attention for extraction of plant-based proteins and tailoring the functionalities of these ingredients. Ultrasonication is generally used as a pretreatment method in the conventional protein solubilization protocols because it can break the cell matrix to improve the extractability. The rate of protein extraction and increase in the extraction yields depend on operating conditions such as sonic energy density, time of sonication, the substrate to slurry ratio, agitation, and so on. Ultrasonication is also applied to modify the physical, structural, and functional properties of protein-based ingredients, besides simultaneous extraction and modifications. Significant changes that occur in protein physical properties due to sonication include size reduction, rheology, electrical conductivity, and zeta (ζ) potential. These changes are due to cavitation-induced shear leading to changes in secondary and tertiary structures, including protein aggregation and cross-linking due to oxidation. Physical and structural changes affect the resulting ingredient functionality and nutritional quality of protein. Changes in the functional properties, especially hydrophobicity, solubility, emulsion, and foaming, depend on the extent of ultrasound energy applied to the protein. This study aims to review major ultrasound process parameters and conditions for extraction and modification of plant proteins and their impact on protein structural changes and resulting physicochemical, functional, and nutritional properties.

High-power sonication of soy proteins: Hydroxyl radicals and their effects on protein structure.

High-power sonication (HPS) is shown to alter protein structure, thus, its functionality, via intermolecular interactions. This study evaluated the effects of HPS on molecular structure of soy proteins in aqueous medium. Free radicals generated during HPS were quantitated using the 5,5-dimethyl-l-pyrrolin N-oxide (DMPO) spin trap method. Electron paramagnetic resonance (EPR) was used to identify them as mostly hydroxyl radicals. The minimum saturation concentration of spin trap solution was determined to be 500 mM of DMPO in water, when exposed to 5 W/cm3 ultrasound power density (PD) for 10 min; subsequently, this concentration was used for quantitating radicals generated in protein samples. Five aqueous soy protein systems, namely, 5% soy protein isolate (SPI), 5% SPI without isoflavonoids (NO-ISO SPI), subunit solutions 1% glycinin (11S) and 1% ß conglycinin (7S), and 10% soy flakes (w/v), were sonicated at 2.5 and 5 W/cm3 PDs. Only adducts of hydroxyl radicals (DMPO-OH) were detected in all of these aqueous systems. The highest concentration (3.68 µM) of DMPO-OH adduct was measured in 11S subunit solution at 5 W/cm3, whereas, the lowest (0.67 µM) was in soy flakes solution at 2.5 W/cm3. PD 5 W/cm3 generated higher concentration of radicals in 7S subunit solution, NO-ISO SPI, and soy flakes protein, compared to sonication at PD 2.5 W/cm3. No change in the protein electrophoretic patterns were observed due to HPS. However, some changes due to HPS were observed in the estimated secondary and tertiary structures, and the contents of free sulfhydryl groups and disulfide bonds in proteins.

Effect of high-power sonication pretreatment on extraction and some physicochemical properties of proteins from chickpea, kidney bean, and soybean.

Impact of high-power sonication (HPS) as pretreatment in extraction and some physicochemical properties of proteins from soybean flakes, flour of soybean, chickpea, and kidney bean was evaluated. Soybean flakes and flours from soybean, chickpea, and kidney bean were dispersed in distilled water (1.10 w/v) and sonicated at two power densities (PD) of 2.5 and 4.5 W/cm3 for 5 min continuously. Proteins were extracted at pH range 8-8.5. PD 2.5 and 4.5 W/cm3 significantly increased protein extraction yields from soy flakes to 29.03% and 25.87%, respectively, compared to 15.28% for unsonicated controls, but did not increase for flours. Freeze-dried spent substrates at higher PD sonication aggregated in size. Free sulfhydryl content for both sonicated and unsonicated soy flakes and flour were similar but increased in chickpea and kidney bean when HPS of 4.5 W/cm3 was applied, indicating the unfolding of protein structure. The protein band patterns for sonicated and unsonicated legumes proteins were found to be similar, indicating no peptide profile alterations by HPS. However, circular dichroism analysis showed changes in secondary structure composition in extracted kidney bean protein causing unfolding and destabilizing the native structure. The secondary structure composition for soy flakes and flour protein and chickpea protein remained unchanged.

Changes and degradation kinetics of some bioactive compounds in dried Orthosiphon aristatus (Java tea) leaves during elevated temperature storage.

BACKGROUND: Orthosiphon aristatus is a traditional medicinal herb mostly used in Southeast Asia and which has many health benefits. Packaging types and storage temperatures were investigated in order to select the best conditions for producing high bioactive compounds (BC) from two kinds of dried O. aristatus leaves. RESULTS: Blanched leaves were vacuum packed in polypropylene (PP) and aluminum foil laminated with polyethylene terephthalate and polyethylene (PET/Al/PE) and dried in a freeze dryer (B_FD) or heat pump-assisted dehumidified dryer (B_HPD60) at 60 °C prior to storage at 15, 25 and 35 °C for 6 months. Leaves in PET/Al/PE bags had higher total phenolic content (TPC), antioxidant activity (AOA) and BC than in PP bags (P ≤ 0.05). Storage at 15 °C retained the highest TPC and AOA in PET/Al/PE bags (P ≤ 0.05). The degradation kinetics for BC, sinensetin and eupatorin followed first-order kinetics. Half-lives (t1/2 ) for BC in PET/Al/PE were higher than in PP and were the highest at 15 °C for both packaging types. CONCLUSIONS: Low temperature and PET/Al/PE bags provided the highest bioactive compound retention. The dried leaves from B_HPD60 and packed in PET/Al/PE bags had higher resistance to degradation of sinensetin than B_FD in PP bags. © 2018 Society of Chemical Industry.

Performance of Bacillus subtilis on fibrous biomass sugar hydrolysates in producing biosurfactants and techno-economic comparison.

Surfactin and fatty acetyl glutamate (FA-Glu) were produced by Bacillus subtilis in 5-L fermentor. In a previous 50-mL shake flask study, sugar hydrolysates from soy hull, alfalfa and switchgrass were shown to support the growth of Bacillus strains. It was observed that glucose content and availability of hexose and pentose sugars in the hydrolysates played an important role in determining growth and product concentration. Growth, economic efficiency and product concentration of biosurfactants was compared in fermentations conducted in 5-L stirred tank bioreactor, on biomass hydrolysate-based growth media. Highest bacterial growth absorbance for surfactin and FA-Glu producing strains were at 3.5 and 3.3 absorbance units, respectively, for switchgrass hydrolysate media. Highest concentrations of products were observed in soy hull hydrolysate media (2.9 g/L and 0.28 g/L for surfactin and FA-Glu). Techno-economic analysis of the 5-L fermentations on the three biomasses showed surfactin cost estimate to be $6.63/kg for 97% pure product.

Extrusion modifies some physicochemical properties of milk protein concentrate for improved performance in high-protein nutrition bars.

BACKGROUND: Extruded and ground milk protein concentrate powders, specifically those with 800 g kg-1 protein (i.e. MPC80), imparted softness, cohesion and textural stability to high-protein nutrition (HPN) bars. The present study evaluated some physicochemical properties of extruded and conventionally produced (i.e. spray-dried) MPC80 to explain these improvements. Protein chemical changes and aggregations within MPC80-formulated HPN bars during storage were characterized. RESULTS: Extruded MPC80 powders had broader particle size distribution (P < 0.05) and smaller volume-weighted mean diameter (P < 0.05) than the spray-dried control. Loose, tapped and particle densities increased (P < 0.05) and correspondingly occluded and interstitial air volumes decreased (P < 0.05) after extruding and milling MPC80. Extrusion decreased water holding capacity (P < 0.05) and solubility (P < 0.05), yet improved the wettability (P < 0.05) of MPC80. MPC80 free sulfhydryl (P < 0.05) and free amine (P < 0.05) concentrations decreased after extrusion. Sulfhydryl and amine concentrations changed (P < 0.05) and disulfide-linked and, more prominently, Maillard-induced aggregates developed during HPN bar storage. CONCLUSION: Extrusion and milling together changed the physicochemical properties of MPC80. Chemical changes and protein aggregations occurred in HPN bars prepared with either type of MPC80. Thus, the physicochemical properties of the formulating powder require consideration for desired HPN bar texture and stability. © 2017 Society of Chemical Industry.

Synthesis of some glucose-fatty acid esters by lipase from Candida antarctica and their emulsion functions.

The synthesis of glucose esters with palmitic acid, lauric acid and hexanoic acid using lipase enzyme was studied and their emulsion functionality in oil-in-water system were compared. Reactions at 3:1M ratio of fatty acids-to-glucose had the highest conversion percentages (over 90% for each of the fatty acid). Initial conversion rate increased as substrate solubility increased. Ester bond formation was confirmed by nuclear magnetic resonance technique that the chemical shifts of glucose H-6 and α-carbon protons of fatty acids in the ester molecules shifted to the higher fields. Contact angle of water on esters' pelleted surface increased as the hydrophobicity increased. Glucose esters' and commercial sucrose esters' functionality as emulsifiers were compared. Glucose esters delayed, but did not prevent coalescence, because the oil droplets diameter doubled during 7days. Sucrose esters prevented coalescence during 7days since the droplets diameter did not have significant change.

Pretreatment of fibrous biomass and growth of biosurfactant-producing Bacillus subtilis on biomass-derived fermentable sugars.

Pretreatment of six fibrous biomasses (switchgrass, alfalfa, soy hulls, soy fiber, DDGS and Baggase) and subsequent hydrolysis using cellulolytic enzymes at a 2.5% (v/v) and 5% (v/v) loading 2.5 (v/v) and 5% (v/v) loading was compared for higher amounts of sugars released. Soaking of biomasses of switchgrass, alfalfa, soy hulls and bagasse in 15% w/w ammonia was optimal at 60 °C for 12 h, followed by enzymatic hydrolysis, yielding 72, 70, 80 and 75% carbohydrate conversions, respectively. However, soaking in ammonia was not needed for soy fiber and DDGS as these contained very little lignin. Ultrasonication for 3 min @ 100% amplitude (170 µM) was found to be optimal for soy fiber and DDGS from which 77 and 83% carbohydrate conversion, respectively, was obtained following enzyme treatment at 5% (w/v) enzyme. The sugars released by enzymatic hydrolysis of pretreated biomass were utilized as an energy source by Bacillus subtilis in fermentation media at 2% (w/v) of concentration. In shake flask trials, cell growth was 15-20% higher on hydrolysates of ammonia-treated switchgrass and alfalfa vs. glucose-based control media due to the presence of a wider range of monomeric sugars (glucose, xylose, arabinose, mannose and galactose). In contrast, growth was less on soy hull hydrolysates prepared with ammonia pretreatment.

Production, health aspects and potential food uses of dairy prebiotic galactooligosaccharides.

Galactooligosaccharides are sugars composed of 3-10 molecules of galactose and glucose via a transgalactosylation reaction mediated by the enzyme ß-galactosidase. Prebiotics are non-digestible food ingredients that pass through the upper digestive system relatively intact and ferment in the lower colon, producing short-chain fatty acids that support the growth of supplemented or indigenous colonic microbiota. Galactooligosaccharides and other prebiotic ingredients are increasingly being recognized as useful dietary tools for the modulation of the colonic microflora toward a healthy balance. Galactooligosaccharides compare well to other oligosaccharides in terms of their prebiotic, immunomodulation, and functional properties in foods. This review elucidates the galactooligosaccharide production process from refined lactose and/or cheese whey permeates, galactooligosaccharide market share and economic value, their health properties, and potential food applications.

Recovery and characterization of α-zein from corn fermentation coproducts.

Zeins were isolated from corn ethanol coproduct distiller's dried grains (DDG) and fractionated into α- and ß Î³-rich fractions. The effects of the ethanol production process, such as fermentation type, protease addition, and DDG drying temperature on zein recovery, were evaluated. Yield, purity, and molecular properties of recovered zein fractions were determined and compared with zein isolated from corn gluten meal (CGM). Around 29-34% of the total zein was recovered from DDG, whereas 83% of total zein was recovered from CGM. Process variations of cooked and raw starch hydrolysis and fermentation did not affect the recovery, purity, and molecular profile of the isolated zeins; however, zein isolated from DDG of raw starch fermentation showed superior solubility and film forming characteristics to those from conventional 2-stage cooked fermentation DDG. Protease addition during fermentation also did not affect the zein yield or molecular profile. The high drying temperature of DDG decreased the purity of isolated zein. SDS-PAGE indicated that all the isolated α-zein fractions contained α-zein of high purity (92%) and trace amounts of ß and γ-zeins cross-contamination. Circular dichroism (CD) spectra confirmed notable changes in the secondary structure of α-zeins of DDG produced from cooked and raw starch fermentation; however, all the α-zeins isolated from DDG and CGM showed a remarkably high order of α-helix structure. Compared to the α-zein of CGM, the α-zein of DDG showed lower recovery and purity but retained its solubility, structure, and film forming characteristics, indicating the potential of producing functional zein from a low-value coproduct for uses as industrial biobased product.

Ultrasound improved ethanol fermentation from cassava chips in cassava-based ethanol plants.

The effects of ultrasound and heat pretreatments on ethanol yields from cassava chips were investigated. Cassava slurries were sonicated for 10 and 30 s at the amplitudes of 80, 160, and 320 microm(pp) (peak to peak amplitude in microm) corresponding to low, medium, and high power levels, respectively. The sonicated and non-sonicated (control) samples were then subjected to simultaneous liquefaction-saccharification and ethanol fermentation. Cassava starch-to-ethanol conversion efficiencies showed that higher ethanol yields were directly related to sonication times, but not to power levels. Significantly higher ethanol yields were observed only for sonicated samples at the high power level. The ethanol yield from the sonicated sample was 2.7-fold higher than yield from the control sample. Starch-to-ethanol conversion rates from sonicated cassava chips were also significantly higher; the fermentation time could be reduced by nearly 24 h for sonicated samples to achieve the same ethanol yield as control samples. Thus, ultrasound pretreatment enhanced both the overall ethanol yield and fermentation rate. When compared to heat-treated samples, the sonicated samples produced nearly 29% more ethanol yield. Combined heat and ultrasound treatment had no significant effect on overall ethanol yields from cassava chips. Ultrasound is also preferable to heat pretreatment because of lower energy requirements, as indicated by energy balances. Integration of ultrasound application in cassava-based ethanol plants can significantly improve ethanol yields and reduce the overall production costs.