Constructing a Titanium Silicon Molecular Sieve-Based Z-Scheme Heterojunction with Enhanced Photocatalytic Activity.

Titanium silicon molecular sieve (TS-1) is an oxidation catalyst that possesses a long lifetime of charge transfer excited state, high Ti utilization efficiency, large specific surface area, and good adsorption property; therefore, TS-1 acts as a Ti-based photocatalyst candidate. In this work, TS-1 coupled Bi2MoO6 (TS-1/BMO) photocatalysts were fabricated via a facile hydrothermal route. Interestingly, the optimized TS-1/BMO-1.0 catalyst exhibited a decent photodegradation property toward tetracycline hydrochloride (85.49% in 120 min) under the irradiation of full spectrum light, which were 4.38 and 1.76 times compared to TS-1 and BMO, respectively. The enhanced photodegradation property of the TS-1/BMO-1.0 catalyst could be attributed to the reinforced light-harvesting capacity of the photocatalyst, high charge mobility, and suitable band structure for tetracycline hydrochloride degradation. In addition, the mechanism of photocatalytic degradation of tetracycline hydrochloride by the TS-1/BMO-1.0 catalyst was reasonably proposed based on the band structure, trapping, and ESR tests. This research provided feasible ideas for the design and construction of high-efficiency photocatalysts for contaminant degradation.

Recent advances in pulse protein conjugation and complexation with polyphenols: an emerging approach to improve protein functionality and health benefits.

Pulses have attracted much attention in the food industry due to their low cost, high yield, and high protein content, which promises to be excellent alternative protein sources. Recently, techniques for covalent and noncovalent binding of pulse proteins to polyphenols are expected to solve the problem of their poor protein functional properties. Additionally, these conjugates and complexes also show several health benefits. This review summarizes the formation of conjugates and complexes between pulse proteins and polyphenols through covalent and noncovalent binding and the impact of this structural change on protein functionalities and potential health benefits. Recent studies show that pulse protein functionalities can be influenced by polyphenol dose. This is mainly the case for adverse effects on solubility and enhancement in emulsifying capacity. Also, the conjugates/complexes exhibit antioxidant activity and can alter protein digestibility. The antioxidant activity of polyphenols could be retained after binding to proteins, while the effect on digestibility depends on the type or dosage of polyphenols. Considering the link between polyphenols and their potential health benefits, pulse polyphenols would be a good choice for producing the conjugates/complexes due to their low cost and proven potential benefits. Further studies on the structure-function-health benefits relationship of pulse protein-polyphenol conjugates and complexes are still required, as well as the validation of their application as functional foods in the food industry.

Ultrasound improving the physical stability of oil-in-water emulsions stabilized by almond proteins.

BACKGROUND: Vegetable proteins are increasingly used to stabilize oil-in-water (O/W) emulsions. However, emulsions are thermodynamically unstable. Recently, high-intensity ultrasound (US) has been used to enhance the stability of emulsions. For these reasons, and considering almond (Prunus dulcis L.) as a good source of high-quality proteins, the aim of this work was to investigate the effect of US treatment on the stability of pre-emulsification O/W emulsions coated with almond protein isolate (API). RESULTS: The influence of API concentration (0.25-2.0 g L-1 ), ion strength (0-500 mmol L-1 NaCl), and pH (3.0-7.0) on the stability of US-treated emulsions was evaluated. US treatment (200-600 W, 25 kHz, 15 min) led to a significant reduction in the particles size of droplets in emulsions, increased critical osmotic pressure and additional protein interfacial adsorption, and thus the formation of more stable emulsions. The more unfolded and random coil structures of the proteins were detected at higher US power, facilitating protein interfacial adsorption. Increasing API concentrations resulted in higher stability of US-treated emulsions against untreated counterparts. The US-treated emulsions were more resistant to salt than untreated samples. In the range from pH 3.0 to7.0, US treatment also enhanced the physical stability of emulsions compared with untreated emulsions. CONCLUSION: US technology could be applied to produce more stable O/W food emulsions stabilized by proteins. © 2018 Society of Chemical Industry.

Phospholipids in foods: prooxidants or antioxidants?

Lipid oxidation is one of the major causes of quality deterioration in natural and processed foods and thus a large economic concern in the food industry. Phospholipids, especially lecithins, are already widely used as natural emulsifiers and have been gaining increasing interest as natural antioxidants to control lipid oxidation. This review summarizes the fatty acid composition and content of phospholipids naturally occurring in several foods. The role of phospholipids as substrates for lipid oxidation is discussed, with a focus on meats and dairy products. Prooxidant and antioxidant mechanisms of phospholipids are also discussed to get a better understanding of the possible opportunities for using phospholipids as food antioxidants.

Fabrication, characterization, and application of pea protein-based edible film enhanced by oregano essential oil (OEO) micro- or nano-emulsion.

Pea protein isolate (PPI)-based active films were prepared by incorporating 0.5 %, 1.0 %, or 2.0 % of oregano essential oil (OEO), either in the form of micro-emulsion (MOEO) or nano-emulsion (NOEO). The particle size and polydispersity index of OEO droplets were 2755.00 nm and 0.63 for MOEO, and 256.30 nm and 0.20 for NOEO. The surface and cross-sectional SEM results revealed the presence of holes and internal pores within the film upon the addition of OEO. The molecular interaction between PPI and OEO was confirmed by FTIR. The addition of OEO significantly increased film thickness, decreased water contact angle, and imparted a more yellow color. At a low concentration (0.5 %), the addition of OEO significantly improved the water vapor barrier and mechanical properties of the film. However, at higher concentrations, these film properties were significantly weakened. Additionally, the film antimicrobial properties were assessed after OEO addition. In vitro inhibition zone results indicated that a 2.0 % addition of OEO significantly suppressed the growth of three Salmonella strains [Salmonella Typhimurium (ATCC14028), Salmonella Infantis 94-1, and Salmonella Enteritidis PT-30]. Application of pea protein-based film with 2.0 % OEO on chicken breast demonstrated significant reduction in microbial count. Our results further showed that reducing the particle size of OEO from micrometer-scale to nanometer-scale in the PPI film matrix did not significantly alter film properties or antimicrobial activities. The study demonstrated that the antibacterial film based on pea protein and OEO is an innovative food packing material for prohibiting bacteria growth on poultry products.

Incorporation of α-Tocopherol into Pea Protein Edible Film Using pH-Shifting and Nanoemulsion Treatments: Enhancing Its Antioxidant Activity without Negative Impacts on Mechanical Properties.

The aim of this study is to develop an antioxidant film based on pea protein isolate (PPI) without sacrificing the packaging properties. To achieve this, α-tocopherol was incorporated to impart antioxidant activity to the film. We investigated the effects on film properties resulting from the addition of α-tocopherol in a nanoemulsion form and pH-shifting treatment of PPI. The results revealed that direct addition of α-tocopherol into un-treated PPI film disrupted film structure and formed a discontinuous film with rough surface, and thereby significantly decreasing the tensile strength and elongation at break. However, pH-shifting treatment in combination with the α-tocopherol nanoemulsion, formed a smooth and compact film, which greatly improved the mechanical properties. It also significantly changed the color and opacity of PPI film, but had little effects on film solubility, moisture content, and water vapor permeability. After the addition of α-tocopherol, the DPPH scavenging ability of PPI film was greatly improved and the release of α-tocopherol was mainly within the first 6 h. Additionally, pH-shifting and nanoemulsion did not affect the film's antioxidant activity nor the release rate. In conclusion, pH-shifting combined with nanoemulsion is an effective method to incorporate hydrophobic compounds such as α-tocopherol into protein-based edible films without negative impacts on film mechanical properties.

Rapid PCR-lateral flow assay for the onsite detection of Atlantic white shrimp.

The Atlantic white shrimp (Litopenaeus setiferus) is of great economic importance to the United States and risk being substituted with imported species due to a shortage in domestic production. To improve the current methods used for the identification of the Atlantic white shrimp species, we designed and validated a robust multiplex PCR-lateral flow assay for the onsite identification of L. setiferus. The standardized assay was validated using a miniaturized, low-cost PCR instrument with 68 shrimp, prawn, and fish samples, spread over fourteen seafood species. L. setiferus was simultaneously amplified by the multiplex assay to give three visual bands, which distinguished it from other species having either one or two bands on the dipstick. The standardized assay showed 100% inclusivity for target L. setiferus samples, 100% exclusivity for non-target samples and can be completed in less than two hours. The assay standardized in this study can be used for onsite testing of L. setiferus samples at processing facilities, restaurants, and wholesalers' facilities.

The fat accumulation promotion effects of dihydrxytetraphenylmethane and its underlying mechanisms via transcriptome analysis.

Dihydrxytetraphenylmethane, also known as Bisphenol BP (BPBP), has been increasingly used in industrial production and more frequently detected in the environment as an alternative plasticizer of BPA. However, there are no reports about BPBP in food safety or its effects on cellular lipogenesis. The purpose of this research was to investigate the influence and potential mechanisms of BPBP on adipogenesis in 3T3-L1 cells. Cells were treated with 4 concentrations (0.01, 0.1, 1, and 10 µM) of BPBP and the results showed that treatment with at low concentrations (0.01 µM) promoted cell fat differentiation and triglyceride accumulation. RNA-seq data showed that a total of 370 differentially expressed genes between control and the low-dose BPBP-treated group were determined, including 227 upregulated genes and 143 downregulated genes. Some key genes related to adipocyte differentiation and adipogenesis were significantly enriched after BPBP treatment, including PPAR-γ, Adipoq, Nr1h3 and Plin1. Pathway analyses suggest that the activation of PPAR-γ signaling pathway may be key for BPBP to promote adipocyte differentiation and fat accumulation. Our work provides evidence for the potential obesogenic effect of BPBP and may call for further research on the safety of the chemical in food products.

Structural characteristics of pea protein isolate (PPI) modified by high-pressure homogenization and its relation to the packaging properties of PPI edible film.

This study modified pea protein isolate (PPI) structure by high-pressure homogenization (HPH) and investigated PPI structural relation to the packaging properties of PPI film. HPH decreased PPI particle size, reduced surface charge, increased surface hydrophobicity, and increased free sulfhydryl, providing greater potential for covalent bonding during film formation. HPH decreased opacity of PPI films from 7.39 to 4.82 at pressure of 240 MPa with more homogeneous surface. The tensile strength and elongation at break were increased from 0.76 MPa to 1.33 MPa and from 96% to 197%, respectively, after treatment at 240 MPa. This improvement was due to the enhanced protein-protein and protein-glycerol hydrogen bonding as evidenced by FTIR. Increased ß-sheet and decreased α-helix by HPH was also observed, and ß-sheet was highly correlated to film tensile strength (Pearson coefficient of 0.973, P < 0.01). Principle component analysis visualized the influence of HPH treatment, and confirmed the association between structural characteristics and film properties.

Antioxidant and prooxidant activities of tea polyphenols in oil-in-water emulsions depend on the level used and the location of proteins.

We studied the impacts of protein location (interface or aqueous phase) on the antioxidant and prooxidant activities of tea polyphenols (TP) in model oil-in-water emulsions (pH 7) at a low (0.01% w/v) or high (0.04 % w/v) concentration. TP at 0.01% reduced the levels of both lipid and protein oxidation markers in emulsions, independent of the protein location. However, TP were more potent when proteins were located at the interface. At 0.04%, TP were only weakly antioxidant towards lipids but were prooxidant towards proteins in emulsions with proteins at the interface, whereas they were still somewhat antioxidant for aqueous phase proteins. These results indicate that TP may act as either antioxidants or prooxidants depending on their concentration and also on the location of the proteins in emulsions. The level of TP should be optimized for emulsion-based foods or beverages to achieve optimum antioxidant activity.

Effects of high-intensity ultrasound on the structural, optical, mechanical and physicochemical properties of pea protein isolate-based edible film.

Pea protein is a promising alternative to animal-based protein and the interest in its application in food industry has been rapidly growing. In this study, pea protein isolates (PPI) were used to form protein-based edible films and the effect of ultrasound treatment on the structure of PPI and the structural, optical, mechanical and physicochemical properties of PPI-films were investigated. Ultrasound induced unfolding of PPI and exposed interior hydrophobic groups to protein surface while both PPI dissociation and formation of large aggregates were observed, as confirmed by measuring intrinsic emission fluorescence, surface hydrophobicity, surface charge, and particle size distribution and polydispersity index, respectively. FE-SEM showed that ultrasound decreased the cracks and protein aggregates at the surface of PPI-film. The film structure was also investigated by FTIR, which showed peak shift in amide I and II region and noticeable difference of protein secondary structure as affected by ultrasound. As a result of such structural changes caused by ultrasound, the properties of PPI-films were improved. Results showed that ultrasound greatly improved the film transparency, significantly increased film tensile strength but not elongation at break, and decreased moisture content and water vapor permeability of the film. This study provided structural data as evidence for utilizing ultrasound technique to develop PPI-films with improved optical, mechanical and water barrier properties.

Combining solid dispersion-based spray drying with cyclodextrin to improve the functionality and mitigate the beany odor of pea protein isolate.

The beany flavor of pea protein limits its application in the food industry. This study aimed at addressing this problem by combining the advantages of solid-based spray drying technique and the ability of cyclodextrins (CD) to entrap volatiles. Pea protein isolates (PPI) was extracted by alkaline extraction-isoelectric precipitation, followed by co-spray drying with CD. The resulted PPI-CD showed no major structure changes. HS-SPME-GC-MS coupled to untargeted metabolomics successfully identified 23 aroma compounds that represent the different odorants among PPI-control, physically mixed PPI-CD, and co-spray dried PPI-CD samples. Heat map analysis also showed a remarkable beany odor mitigation effect upon the addition of CD, which was further proved to be due to CD entrapping aroma compounds during spray drying. In the meantime, the functional attributes of PPI-CD were not adversely impacted by the addition of CD.

Physical properties and cookie-making performance of oleogels prepared with crude and refined soybean oil: a comparative study.

The objective of this research was to fabricate crude soybean oil oleogels (CSO) using ß-sitosterol (BS) and/or monoacylglycerol (MAG) and compare their role with that of refined soybean oil oleogels (RSO) in cookie making. Both crude and refined soybean oil oleogels were formed with BS or MAG, or the combination of both (1 : 1) at a fixed concentration of 10 wt%. The thermal behavior of the oleogels was measured using differential scanning calorimetry (DSC). The crystal structure and morphology of the oleogels were characterized using X-ray diffraction (XRD) and polarized light microscopy (PLM). The hardness of the oleogel and commercial vegetable shortening was compared using a texture analyzer. The characteristics of cookies made with the oleogels were compared with those of cookies made with commercial vegetable shortening. Overall, the incorporation of BS and/or MAG into crude and refined soybean oil can produce oleogels with solid-like properties. Refined soybean oil formed stronger and firmer oleogels as compared to crude soybean oil. RSO structured by BS presented branched fiber-like, elongated plate-like, and needle-like crystals while the same oil gelled by MAG contained spherulite crystals. RSO made with the combination of BS and MAG displayed crystal morphologies from both BS and MAG. The same crystal morphologies were observed in CSO with lower quantities. Comparing the quality of cookies made with the oleogels and commercial vegetable shortening, equal or better performance of both RSO and CSO in terms of weight, thickness, width, spread ratio, and hardness of cookies than that of commercial vegetable shortening was observed. By combining the results of the physical characterization and cookie making performance, it can be concluded that both crude and refined soybean oleogels could resemble commercial shortening, which offers the possibility of using oleogels to replace shortening in the baking industry.

Formation, characterization, and potential food application of rice bran wax oleogels: Expeller-pressed corn germ oil versus refined corn oil.

The expeller-pressed (EP) corn germ oil oleogels were prepared using rice bran wax (RBX) at different concentrations (3, 5, 7, and 9 wt%). Their structural properties, including color, hardness, thermal behavior, rheological property, and crystal structure were evaluated. The performance of oleogels for potential food application was examined by incorporating oleogels into cookies as a fully replacement for commercial shortenings. Overall, RBX could form oleogels in both refined and EP corn germ oils at a concentration ≥3 wt%. Refined corn oil produced a stronger gel than crude corn oil. When comparing cookie characteristics, cookies made with both types of oleogels showed similar properties with commercial cookies. This result indicates that oleogels made by refined and EP corn germ oil together with RBX have the potential to imitate the functionality of commercial shortening in the baking industry.

Effect of alkaline extraction pH on structure properties, solubility, and beany flavor of yellow pea protein isolate.

In the current study, the impact of alkaline extraction pH (8.5, 9.0, and 9.5) on chemical composition, molecular structure, solubility and aromatic profile of PPI was investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the quantification of free sulfhydryl group and disulfide bond contents, size exclusion chromatography with multi-angle static light scattering and refractive index (SEC-MALS-RI), circular dichroism (CD) spectroscopy, and headspace solid phase micro extraction gas chromatography-mass spectroscopy (HS-SPME-GC-MS). We found that protein recovery yield increased from 49.20% to 57.56% as the alkaline extraction pH increased from 8.5 to 9.5. However, increasing the extraction pH promoted the formation of protein aggregates which decreased the percent protein solubility although there was no influence on protein secondary structure. PPI extracted at pH 9.0 possessed the lowest beany flavor as revealed by the selected six beany flavor markers including alcohols, aldehydes, ketones and pyrazine. The lowest lipoxygenase activity at pH 9.0 may contribute to the least beany flavor in PPI. Therefore, pH 9.0 was found to be the optimal condition for preparing premium PPI in terms of yield, functionality, and aromatic profile using alkaline extraction-isoelectric precipitation process. The findings could have fundamental implications for the preparation and utilization of pea proteins in food applications.

New Insights into the Impact of Sodium Chloride on the Lipid Oxidation of Oil-in-Water Emulsions.

Salt, most often sodium chloride (NaCl), is commonly used in a variety of food emulsions. However, little is known about the detailed mechanism of how NaCl influences the lipid oxidation and thus the shelf life of those products. In this study, we report a new mechanism through which NaCl could help inhibit the lipid oxidation of sodium dodecyl sulfate (SDS)-stabilized oil-in-water (O/W) emulsions. Results showed that NaCl significantly lowered the critical micelle concentration (CMC) of SDS, which further led to greater amounts of lipid hydroperoxides being solubilized by SDS micelles into the aqueous phase of emulsion. NaCl also altered the distribution of δ-tocopherol between the aqueous and oil phase of emulsion. Such changes of the physical locations of lipid hydroperoxides and δ-tocopherol were responsible for the improved oxidative stability of NaCl-added O/W emulsions in the absence or presence of δ-tocopherol.

The prooxidant activity of salts on the lipid oxidation of lecithin-stabilized oil-in-water emulsions.

Salts reduction/substitution have gained a lot interest from food industry since the US Food and Drug Administration (FDA) has issued a draft guidance for salt reduction. However how changes of salts in food formulation could influence lipid oxidation is still not fully understood. Using oil-in-water emulsions stabilized by a natural emulsifier - lecithin at pH 7.0 as a model system, this study evaluated how salts affect the physical parameters of the emulsion, the chelating activity of lecithin and thus the lipid oxidation of these emulsions. Results showed that salts increased the particle size, the negative charge of the oil droplets, and the amount of iron chelated by lecithin. Lipid oxidation lag phases were shortened by addition of salts, by 1 day and 2 days for lipid hydroperoxides and thiobarbituric acid reactive substances measurements respectively. These results provide some new insights on the mechanisms of how salts could affect the lipid oxidation of food emulsions.

Physical and oxidation stability of self-emulsifying krill oil-in-water emulsions.

Krill oil is a unique source of omega-3 fatty acids since it is a mixture of phospholipids and triacylglycerols. Due to the presence of phospholipids, it can form oil-in-water emulsions without additional food additives. In this work, the physical stability of krill oil-in-water emulsions was determined at various pH values (3-7) and NaCl concentrations (50-1000 mM). The initial particle size ranged from 150 to 165 nm. The emulsions were the most stable at pH ≥ 5.0 and salt concentrations below 100 mM. Lipid oxidation was accelerated by iron and inhibited by Trolox and α-tocopherol. Trolox was a more effective antioxidant than α-tocopherol. α-Tocopherol had a better inhibitory effect when it was added after homogenization than when added to the lipid prior to homogenization. These results indicate that krill oil emulsions could represent a self-emulsifying, oxidatively stable source of omega-3 fatty acids that may be used in functional foods.

Effects of salts on oxidative stability of lipids in Tween-20 stabilized oil-in-water emulsions.

Lipid oxidation in oil-in-water (O/W) emulsions is an important factor determining the shelf life of food products. Salts are often present in many types of emulsion based food products. However, there is limited information on influence of salts on lipid oxidation in O/W emulsions. Thus, the purpose of this study was to examine the effects of sodium and potassium chloride on lipid oxidation in O/W emulsions. Tween 20 stabilized corn O/W emulsions at pH 7.0 were prepared with different concentrations of sodium chloride with or without the metal chelators. NaCl did not cause any changes in emulsion droplet size. NaCl dose-dependently promoted lipid oxidation as measured by the lipid oxidation product, hexanal. Both deferoxamine (DFO) and ethylenediaminetetraacetic acid (EDTA) reduced lipid oxidation in emulsions with NaCl, with EDTA being more effective. Potassium chloride showed similar impact on lipid oxidation as sodium chloride. These results suggest that salts are able to promote lipid oxidation in emulsions and this effect can be controlled by metal chelators.