Physicochemical characterization of wheat starch and variation of fatty acid composition in deep-fried dough sticks with different treatments.

The present study investigated the effects of different deep-frying times and temperatures on the amylose content, crystal structure, thermodynamics, and other properties of deep-fried dough sticks. Results showed that the change of amylose content in deep-fried dough sticks during the deep-frying process was positively correlated with time and temperature. Moreover, the deep-frying process of deep-fried dough sticks was accompanied by the formation of starch-lipid complexes that led to the destruction of starch structure. The degreased sample and the oil sample had the same absorption peaks at 2854 and 1746 cm-1, respectively. The melting enthalpy (ΔH) of the starch-lipid complex decreased significantly. In addition, the viscosity of starch reduced as the deep-frying time and temperature increased. Furthermore, it was found that the effect of increasing deep-frying temperature was greater than that of time. PRACTICAL APPLICATION: As a popular deep-fried food, the main component of deep-fried dough sticks is starch. Starch gelatinization, protein denaturation, and interaction among components occurred during deep-frying. At present, there are few studies focusing on the properties of starch in deep-fried dough sticks in the real deep-frying system. Therefore, this study provided a theoretical basis for subsequent research by measuring the effects of different deep-frying conditions on the properties of starch in deep-fried dough sticks.

Spray drying the Pickering emulsions stabilized by chitosan/ovalbumin polyelectrolyte complexes for the production of oxidation stable tuna oil microcapsules.

The microencapsulation of polysaturated fatty acids by spray drying remains a challenge due to their susceptibility to oxidation. In this work, antioxidant Pickering emulsions were attempted as feeds to produce oxidation stable tuna oil microcapsules. The results indicated that the association between chitosan (CS) and ovalbumin (OVA) was a feasible way to fabricate antioxidant and wettable complexes and a high CS percentage favored these properties. The particles could yield tuna oil Pickering emulsions with enhanced oxidation stability through high-pressure homogenization, which were successfully spray dried to produce microcapsules with surface oil content of 8.84 % and microencapsulation efficiency of 76.65 %. The microcapsules exhibited significantly improved oxidation stability and their optimum peroxide values after storage at 50 °C, 85 % relative humidity, or natural light for 15 d were 48.67 %, 60.07 %, and 39.69 % respectively lower than the powder derived from the OVA-stabilized emulsion. Hence, Pickering emulsions stabilized by the CS/OVA polyelectrolyte complexes are potential in the production of oxidation stable polyunsaturated fatty acid microcapsules by spray drying.

Antibacterial activity of lysozyme after association with carboxymethyl konjac glucomannan.

The unique high isoelectric point of lysozyme (LYZ) restricts its application in composite antibacterial coating due to the unfavorable liability to electrostatic interaction with other components. In this work, the antibacterial activity of a dispersible LYZ-carboxymethyl konjac glucomannan (CMKGM) polyelectrolyte complex was evaluated. Kinetic analysis revealed that, compared with free LYZ, the complexed enzyme exhibited decreased affinity (Km) but markedly increased Vmax against Micrococcus lysodeikticus, and QCM and dynamic light scattering analysis confirmed that the complex could bind with the substrate but in a much lower ratio. The complexation with CMKGM did not alter the antibacterial spectrum of LYZ, and the complex exerted antibacterial function by delaying the logarithmic growth phase and impairing the cell integrity of Staphylococcus aureus. Since the LYZ-CMKGM complex is dispersible in water and could be assembled easily, it has great potential as an edible coating in food preservation.

Effect of UV-A Irradiation on Bioactive Compounds Accumulation and Hypoglycemia-Related Enzymes Activities of Broccoli and Radish Sprouts.

In the present study, different intensities of UV-A were applied to compare their effects on growth, bioactive compounds and hypoglycemia-related enzyme activities in broccoli and radish sprouts. The growth of sprouts was decreased after UV-A irradiation. A total of 12 W of UV-A irradiation resulted in the highest content of anthocyanin, chlorophyll, polyphenol and ascorbic acid in broccoli and radish sprouts. The highest soluble sugar content was recorded in sprouts under 8 W of UV-A irradiation, while no significant difference was obtained in soluble protein content among different UV-A intensities. Furthermore, 12 W of UV-A irradiation induced the highest glucosinolate accumulation, especially glucoraphanin and glucoraphenin in broccoli and radish sprouts, respectively; thus, it enhanced sulforaphane and sulforaphene formation. The α-amylase, α-glucosidase and pancrelipase inhibitory rates of two kinds of sprouts were enhanced significantly after UV-A irradiation, indicating UV-A-irradiation-treated broccoli and radish sprouts have new prospects as hypoglycemic functional foods.

Regulation of interfacial mechanics of soy protein via co-extraction with flaxseed protein for efficient fabrication of foams and emulsions.

Enrichment of plant proteins with functionality is of great importance for expanding their application in food formulations. This study proposed an innovation to co-enrich soy protein and flaxseed protein to act as efficient interfacial stabilizers for generating foams and emulsions. The structure, interfacial properties, and functionalities of the soy protein-flaxseed protein natural nanoparticles (SFNPs) obtained by alkali extraction-isoelectric precipitation (AE) and salt extraction-dialysis (SE) methods were investigated. Overall, the foamability of AE-SFNPs (194.67 %) was 1.45-fold that of SE-SFNPs, due to their more flexible structure, smaller particle size, and suitable surface wettability, promoting diffusion and adsorption at the air-water interface. AE-SFNPs showed higher emulsion stability (140.89 min), probably because the adsorbed AE-SFNPs with smaller size displayed soft particle-like properties and stronger interfacial flexibility, and therefore could densely and evenly arrange at the interface, facilitating the formation of a stiff and solid-like interfacial layer, beneficial for more stable emulsion formation. The findings may innovatively expand the applications of SFNPs as food ingredients.

Characterization and stability evaluation of Ca2+ cross-linked soybean protein isolate/chitosan/sodium alginate ternary complex coacervate phase.

To improve the stability of the soybean protein isolate/chitosan/sodium alginate ternary complex coacervate phase against environmental pH and ionic strength, the complex ternary phase cross-linked by Ca2+ was characterized and evaluated. The viscoelastic properties, thermal properties, microstructure, and texture profile were characterized using rheology, differentia scanning calorimetry as well as thermmogravimetric analysis, scanning electron microscopy as well as transmission electron microscopy, and texture profile analysis, respectively. Compared with the uncross-linked ternary complex coacervate, the complex in situ cross-linked with 1.0 % Ca2+ for 1 h still retains its typical solid characteristics, and has a more compact network structure and better stability. Our research results also showed that prolonging the cross-linking time (from 3 h to 5 h) and increasing the concentration of the cross-linking agent (from 1.5 % to 2.0 %) did not further improve the rheological, thermodynamic and textural properties of the complex coacervate. The ternary complex coacervate phase cross-linked in situ under 1.5 % concentration of Ca2+ for 3 h showed significantly improved stability at low pH 1.5-3.0, which indicats that the ternary complex coacervate phase cross-linked in situ by Ca2+ can be used as a potential delivery platform for the effective delivery of biomolecules under physiological conditions.

Interfacial adsorption behavior of the Aspergillus oryzae lipase-chitosan complex and stability evaluation of the resultant Pickering emulsion.

To prompt the application of the chitosan (CS)-Aspergillus oryzae lipase (AOL) complex in the construction of novel biphasic catalysis medium, its Pickering emulsion stabilization ability as well as adsorption behavior in the oil-water interface were investigated and the stability of resultant emulsion was evaluated. The results indicated that the CS-AOL complex assembled in mass ratio 1:5 was an effective Pickering stabilizer and up to 90 % AOL could be retained in the emulsion interface. Quartz crystal microbalance with dissipation monitoring suggested that the CS-AOL complex spontaneously absorbed to oil-water interface; absorption dynamics analysis revealed that the adsorption was driven by diffusion accompanied by rapid structural rearrangement; while interfacial dilatational rheology demonstrated the formation of an elastic film in the oil-water interface. The Pickering emulsions were pseudoplastic and that in oil fraction 0.6 exhibited the elastic behavior in contrast to the viscous behavior in oil fractions 0.2 and 0.4. The Pickering emulsion exhibited excellent stability against storage for up to 28 d, pHs 2.0-12.0, heating at 25-90 °C, and up to 500 mmol/L NaCl, and the corresponding interfacial AOL retentions exceeded 80 % during exposure to these conditions. Hence, the CS-AOL complex could be used as a stabilizer to construct Pickering emulsion-based biphasic catalysis systems.

Addition of Chelators Increased the Stability of Black Rice Anthocyanins against the Metallic Ions in Tap Water and Improved the Coloration of Steamed Cold Noodles.

The anthocyanins in black rice extract (BRA) are sensitive to metallic ions, which restrict its application in the coloration of steamed cold noodles in China that uses tap water as the solvent. Food-grade chelators were added to check if they could increase the stability of BRA. The results indicated that the color decay of BRA in tap water was mainly caused by Fe3+, Cu2+, and Fe2+, and the addition of chelators could effectively antagonize this effect. Coloration with the BRA solution containing the optimized chelator formulation of 0.01% ethylenediaminetetraacetic acid disodium, 0.08% sodium hexametaphosphate, and 0.064% sodium tartrate conferred comparable appearance and chromatic attributes with those of the noodle colored by deionized water-dissolved BRA. The steamed cold noodles colored by the chelators-containing BRA exhibited increased springiness and decreased starch retrogradation, and possessed potential health functions due to its slightly increased resistant starch content and markedly enhanced antioxidant capacity. Hence, the addition of chelators is a feasible way to increase the color stability of BRA in tap water, and the chelators-supplemented BRA could be used to produce steamed cold noodles with attractive color and health benefits.

Formation of Starch-Lipid Complexes during the Deep-Frying Process and Its Effects on Lipid Oxidation.

In the present study, maize starch (MS), potato starch (PS), high-amylose maize starch (HAMS), and wheat starch (WS) were deep-fried in soybean oil that was continuously heated for 40 h under 180 °C. The thermodynamic and pasting properties of deep-fried starch samples were determined. The results suggested that starch−lipid complexes formed with the extension of frying oils' usage; however, their number was not dependent on the frying oils' life cycle. Importantly, the results of pasting properties revealed the following strength of intermolecular force in deep-fried starch samples: PS > MS > HAMS > WS. The results of XRD and FTIR analysis confirmed the formation of starch−lipid complexes during the deep-frying process. Furthermore, the results of the in vitro digestibility of deep-fried starch revealed that the formation of starch−lipid complexes inhibited the swelling of starch granules and prevented the entrance of amylase into the interior. Additionally, the results of the oxidation stability of deep-frying oil indicated that the formation of starch−lipid complexes did not alter the trend of lipid oxidation as an effect of the limited number of starch−lipid complexes. These results could have critical implications for the development of healthier deep-fried foods.

Enhancement of ultrasound-assisted extraction of sulforaphane from broccoli seeds via the application of microwave pretreatment.

In this study, microwave pretreatment and grinding treatment were used to enhance sulforaphane formation, then ultrasonic-assisted extraction (UAE) was applied to extract sulforaphane using simultaneous hydrolysis and extraction method. The effects of various parameters, which were ultrasonic time,ultrasonic power, solid-water ratio and solid-ethyl acetate ratio on the extraction rate of sulforaphane were investigated. The results showed that microwave pretreatment enhanced sulforaphane formation. Excessive size reduction did not increase or even reduced extraction rate of sulforaphane. Simultaneous hydrolysis and extraction significantly increased extraction rate of sulforaphane compared to hydrolysis followed by extraction. UAE accelerated mass transfer and the solubilization of the targeted compounds due to the acoustic cavitation effect, thus enhanced enzymatic hydrolysis of glucoraphanin and the extraction rate of sulforaphane. The extraction rate of sulforaphane using UAE with simultaneous hydrolysis and extraction was 4.07-fold of the conventional extraction method. UAE was an effective method to extract sulforaphane from broccoli seeds since it led to higher yield of sulforaphane in a much shorter extraction time.

Preparation of powdered oil by spray drying the Pickering emulsion stabilized by ovalbumin - Gum Arabic polyelectrolyte complex.

The suitability of the perilla seed oil Pickering emulsion stabilized by the ovalbumin (OVA) - gum Arabic (GA) polyelectrolyte complex for spray drying was investigated and the resultant powder was characterized. The OVA - GA complex conferred enhanced stability to the emulsion than OVA, GA, and their mixture. The viscosity of the Pickering emulsion was highly sensitive to stabilizer concentration and that fabricated by 2% OVA - GA complex showed acceptable viscosity and powder yield. The Pickering emulsion was more effective in preventing oil leakage during spray drying than the OVA-stabilized emulsion and the resultant powder possessed an oil content of up to 77.7%. Besides, the spray-dried Pickering emulsion powder showed greater rehydration and better flowability than that of the OVA-stabilized emulsion powder. Hence, the Pickering emulsion stabilized by the OVA - GA polyelectrolyte complex is promising as a novel feed for the production of oil powders by spray drying.

Fabrication of lipase-loaded particles by coacervation with chitosan.

Coacervation of the lipase from Aspergillus oryzae (AOL) with chitosan was a feasible way to fabricate lipase-loaded particles and the optimum conditions were phase separation pH 5.5, chitosan to AOL mass ratio 1:5, and temperature 25 °C in the absence of NaCl, which conferred an AOL loading efficiency of up to 95.48% and activity recovery of 69.60%. The AOL-chitosan coacervates were highly porous and more susceptible to weight loss upon heating. Coacervation with chitosan increased the activity of AOL and shifted its optimum pH from 7.0 to 6.0, but exerted no effect on its optimum temperature (45 °C). Thermal deactivation kinetics analysis revealed that the coacervated AOL was more thermal stable, while the Michaelis-Menten kinetics analysis indicated that coacervation with chitosan increased the Vmax of AOL by 2.4 folds, but decreased its substrate affinity by 3.6 folds. Hence, the AOL-chitosan coacervates are potential in the construction of Pickering emulsion-based lipase catalysis systems.

Effect of different LED lights on aliphatic glucosinolates metabolism and biochemical characteristics in broccoli sprouts.

In this study, various LED lights (white, red, yellow, green, blue and purple) were applied to evaluate their effects on the biochemical parameters, aliphatic glucosinolates synthesis and sulforaphane formation in broccoli sprouts. The length of broccoli sprouts and bulk water content were decreased after LED light treatments, especially white, green, and purple LED lights. The highest contents of ascorbic acid and anthocyanins were recorded in blue LED light treated broccoli sprouts. Green LED light treated sprouts contained the highest contents of ATP, ADP and AMP. Yellow and bule lights resulted in higher glucose content. Yellow, blue, and purple LED lights induced glucoraphanin and glucoerucin accumulation via upregulating aliphatic glucosinolates biosynthetic genes. Yellow LED light caused higher glucoraphanin content than blue LED light, while sulforaphane formation showed no difference; which might be attributed to higher myrosinase activity and its expression as well as lower ESM1 expression under blue LED light.

Release of Leu-Pro-Pro from corn gluten meal by fermentation with a Lactobacillus helveticus strain.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitory peptides are potential alternatives to the synthetic ACE inhibitory drugs, but the in vivo antihypertensive effects of most of them have not been confirmed. The tripeptide Leu-Pro-Pro (LPP) is one of the few peptides that have been proved clinically effective in reducing the blood pressure of hypertensive patients and casein is currently its major source. LPP is contained in multiple fractions of zein, and corn gluten meal (CGM) is hence a potential new source of LPP. For this purpose, CGM was fermented with a Lactobacillus helveticus strain and the medium composition was optimized; the decoloration of the resultant hydrolysate was investigated as well. RESULTS: LPP could be successfully released from CGM by fermentation with the strain Lactobacillus helveticus CICC 22536. The highest LPP content and protein recovery of 561 mg kg-1 and 14.92% occurred in the medium containing 20 g L-1 glucose, 15 g L-1 beef extract, 60 g L-1 CGM, 10 g L-1 CaCO3 , 0.5 g L-1 NaCl, and inoculation amount 6%. The supplementation of Flavourzyme® further improved the two parameters to 662 mg kg-1 and 36.94%, respectively. The permeate of the hydrolysate after ultrafiltration through a 5 kDa membrane could be effectively decolored by the macroporous resin XAD-16 without notable protein loss, and its LPP content was further boosted to 743 mg kg-1 . CONCLUSION: CGM is a potential new source of LPP and its ultrafiltered and decolored hydrolysate could be used to develop new antihypertensive functional foods. © 2021 Society of Chemical Industry.

Carboxymethyl konjac glucomannan coating on multilayered emulsions for improved bioavailability and targeted delivery of curcumin.

Curcumin was entrapped in multilayered emulsions to increase its stability and bioavailability. Curcumin emulsion stabilized by whey protein isolate (WPI) was coated with chitosan (CHI) or carboxymethyl konjac glucomannan (CMKGM) alone to form secondary emulsions and their combination in sequence to form the tertiary emulsion, in which, the polyelectrolyte concentrations were 1.0% WPI for the primary emulsion, 0.4% CMKGM for the secondary emulsion -CMKGM, 0.2% CHI for the secondary emulsion -CHI, and 0.1% CMKGM for the tertiary emulsion. The characteristics of the emulsions, including their particle size, ζ potential, microstructure, creaming stability, and biopolymer distribution, were investigated and their colon-targeted delivery potential was evaluated through both in vitro and in vivo studies as well. The curcumin-loaded secondary and tertiary emulsions were stable with a narrow size distribution and were generated by layer-by-layer assembly according to confocal laser scanning microscope observation. When CMKGM was located at the outermost layer, the corresponding secondary and tertiary emulsions showed a greatly reduced release of curcumin in the simulated gastric fluid, but exhibited increased release in the ß-mannanase-containing simulated colonic fluid. In vivo evaluation in mice demonstrated that the bioavailability of curcumin in the CMKGM-coated secondary and tertiary emulsions was increased by about 4 folds compared with that of free curcumin and curcumin could be released in a sustainable manner. These results demonstrated that multilayered emulsions coated with CMKGM could promote curcumin absorption in the gastrointestinal tract and hence is a promising colon-targeted delivery system for curcumin.

Calcium affects glucoraphanin metabolism in broccoli sprouts under ZnSO4 stress.

CaCl2, Ca2+ chelator (EGTA) and Ca2+ channel blocker (verapamil) were used to investigate mechanism of glucoraphanin metabolism in broccoli sprouts under ZnSO4 stress. CaCl2 treatment promoted sprout growth, reduced MDA (malonaldehyde) content and electrolyte leakage in sprouts under ZnSO4 stress. The highest MDA content and electrolyte leakage were obtained in ZnSO4 plus verapamil-treated sprouts. In addition, ZnSO4 plus CaCl2 treatment significantly enhanced glucoraphanin content and sulforaphane formation, while an opposite result was observed after ZnSO4 plus EGTA treatment; which were further supported by expression of glucoraphanin biosynthetic and hydrolytic genes as well as myrosinase (MYR) and epithiospecifier protein (ESP) activities. These results indicated that exogenous and endogenous calcium promoted glucoraphanin biosynthesis and the conversion rate of glucoraphanin into sulforaphane. Verapamil treatment also stimulated glucoraphanin biosynthesis, but exerted an adverse influence on sulforaphane formation from the hydrolysis of glucoraphanin because of much higher ESP expression and ESP activity than ZnSO4 treatment.

Research on the mechanism of microwave-toughened starch on glucolipid metabolism in mice.

Potato resistant starch (RS) was prepared by microwave-toughening treatment (MTT). This study investigated the beneficial effects of RS on high-fat diet (HFD)-induced hyperlipidemia in C57BL/6J mice by evaluating changes in the gut microbiota. The mice were fed low-fat diet with corn starch, HFD with corn starch, HFD with potato starch (HFP), or HFD with RS (HFR) for 6 weeks. The results showed that the HFR group had lower body weight and total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels compared with the HFP group. Moreover, the brown adipose tissue levels of uncoupling protein 1 (UCP-1), ß3-adrenoceptor (ß3-AR), peroxisome proliferator-activated receptor-γ (PPAR-γ), and PPAR-γ coactivator-1α (PGC-1α) were increased. Our results showed that RS supplementation increased the Bacteroidetes/Firmicutes ratio and the abundance of short-chain fatty acid-producing Allobaculum, Ruminococcus, and Blautia. Our data suggest that RS prepared by MTT may be used as a prebiotic agent to prevent gut dysbiosis and obesity-related chronic diseases, such as hyperlipidemia, and obesity.

Investigation of Microstructure Evolution and Phase Selection of Peritectic Cuce Alloy During High-Temperature Gradient Directional Solidification.

In this work, a CuCe alloy was prepared using a directional solidification method at a series of withdrawal rates of 100, 25, 10, 8, and 5 µm/s. We found that the primary phase microstructure transforms from cellular crystals to cellular peritectic coupled growth and eventually, changes into dendrites as the withdrawal rate increases. The phase constituents in the directionally solidified samples were confirmed to be Cu2Ce, CuCe, and CuCe + Ce eutectics. The primary dendrite spacing was significantly refined with an increasing withdrawal rate, resulting in higher compressive strength and strain. Moreover, the cellular peritectic coupled growth at 10 µm/s further strengthened the alloy, with its compressive property reaching the maximum value of 266 MPa. Directional solidification was proven to be an impactful method to enhance the mechanical properties and produce well-aligned in situ composites in peritectic systems.

Cationic polyelectrolyte/graphene oxide as an efficient sorbent for the extraction and analysis of trace acidic herbicides in vegetables.

The facile preparation and characterization of a cationic polyelectrolyte (polydiallyldimethylammonium chloride, PDDA) fabricated graphene oxide-grafted silica microsphere (PDDA@GO@Sil) with high positive charge density as the sorbent for the high selective capture of acidic herbicides were reported. The theoretical calculation showed that there were strong adsorption energies between the PDDA and analytes, and the main interaction was the hydrogen bonding from OH…Cl and CO…HC. Static- and dynamic- state adsorption results indicated that acidic herbicides were the monolayer coverage onto the PDDA@GO@Sil due to the electrostatic attraction between the sorbent and analytes, and electrostatic repulsion among analytes. Under the optimized conditions obtained with the single-factor experiment and response surface methodology, this established method was used for the enrichment and determination of herbicides in two vegetables. Method detection limits were in the range of 0.75-1.50 µg L-1 indicating that the introduction of PDDA provided the excellent extraction capacity toward acidic herbicides. The obtained results exhibited that the developed method was feasible, reliable, selective and accurate for the determination of acidic herbicides in real samples.

Maillard reaction in protein - polysaccharide coacervated microcapsules and its effects on microcapsule properties.

The occurrence of Maillard reaction in protein - polysaccharide coacervated microcapsules and its effects on microcapsule properties were investigated. Vitamin E microcapsules were prepared by soybean protein isolate - chitosan coacervation at 50 °C, 70 °C, or 90 °C for 12 h in the presence of maltose. Chromatic and furosine measurements revealed that Maillard reaction occurred in the microcapsules and was favored by high incubation temperatures. The three coacervation temperatures did not destroy the microcapsule structure, but improved the microencapsulation efficiency and microencapsulation yield instead. The microcapsules exhibited decreased aggregation and the increased absolute zeta potential and particle size were believed contribute to this improvement. Stability analysis demonstrated that the microcapsules possessed enhanced resistance to dissolution in water and improved storage stability than control microcapsules. It is concluded that coacervation at a temperature high enough to initiate Maillard reaction is a promising way to improve the physiochemical properties of protein - polysaccharide coacervated microcapsules.