Anti-fungal effects of lactic acid bacteria from pickles on the growth and sterigmatocystin production of Aspergillus versicolor.

Sterigmatocystin (STC) is an emerging mycotoxin that poses a significant threat to the food security of cereal crops. To mitigate STC contamination in maize, this study employed selected lactic acid bacteria as biocontrol agents against Aspergillus versicolor, evaluating their biocontrol potential and analyzing the underlying mechanisms. Lactiplantibacillus plantarum HJ10, isolated from pickle, exhibited substantial in vitro antifungal activity and passed safety assessments, including antibiotic resistance and hemolysis tests. In vivo experiments demonstrated that L. plantarum HJ10 significantly reduced the contents of A. versicolor and STC in maize (both >84 %). The impact of heat, enzymes, alkali, and other treatments on the antifungal activity of cell-free supernatant (CFS) was investigated. Integrated ultra-high-performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS) analysis revealed that lactic acid, acetic acid, and formic acid are the key substances responsible for the in vitro antifungal activity of L. plantarum HJ10. These metabolites induced mold apoptosis by disrupting cell wall structure, increasing cell membrane fluidity, reducing enzyme activities, and disrupting energy metabolism. However, in vivo antagonism by L. plantarum HJ10 primarily occurs through organic acid production and competition for growth space and nutrients. This study highlights the potential of L. plantarum HJ10 in reducing A. versicolor and STC contamination in maize.

Effect of oleic acid-rich rapeseed oil on the physicochemical, rheological, and structural characteristics of wheat dough.

Some wheat-based foods require different doses of oil to moderate quality of dough during processing and the influence mechanisms remain unclear. Therefore, the effect of rapeseed oil addition on physicochemical characteristics and fine structure of dough and underlying mechanism were elucidated by rheometer, scanning microscope and molecular spectroscopic method. Results showed that compared with native dough (without exogenous rapeseed oil), the addition of rapeseed oil changed the fine structure, improved extensibility, but reduced viscoelasticity of the dough. Moreover, high addition especially 20 wt% oil (based on wheat flour) significantly changed gelatinization and retrogradation behaviors of the dough, whilst disrupted gluten network and increased random coil content (32.1%) of dough except that decreased its α-helix (21.2%), ß-sheet (23.1%), disulfide bond (7.9 µmol/g) compared with native dough which were 16.3%, 29.2%, 33.1%, 11.0 µmol/g, respectively. Results in the study could provide a certain understanding for application of vegetable oils in wheat-based products.

Degradation and transformation mechanisms of pungent substances in huajiao (Zanthoxylum bungeanum) oil during storage: Induced by ultraviolet irradiation.

The pungency of huajiao (scientifically known as Zanthoxylum bungeanum) oil (ZBO), a crucial seasoning oil, is notably influenced by storage conditions, an aspect insufficiently explored in current research. Through the use of high-performance liquid chromatography and liquid chromatography-mass spectrometry, this study systematically investigated the stability of pungent compounds in ZBO under various storage conditions. It also elucidated the degradation and transformation mechanisms of these substances when exposed to ultraviolet (UV) irradiation. The results underscore elevated temperature, light exposure, oxygen, and storage duration as pivotal factors influencing compound degradation, with UV light emerging as the primary driving force. After 48 h of UV exposure, the primary pungent compound, hydroxy-α-sanshool, experienced a significant loss of 85.49%, indicating a pronounced inclination towards isomerization and oxidation. Notably, this study reveals, for the first time, the possible degradation-transformation pattern of hydroxy-γ-sanshool: a mutual conversion with hydroxy-γ-isosanshool and isomerization to (2E,4E,8Z,10E,12Z)-N-(2-hydroxy-2-methylpropyl) tetradeca-2,4,8,10,12-pentaenamide.

Antifungal mechanisms of binary combinations of volatile organic compounds produced by lactic acid bacteria strains against Aspergillusflavus.

Aspergillus flavus（A. flavus）, a common humic fungus known for its ability to infect agricultural products, served as the subject of investigation in this study. The primary objective was to assess the antifungal efficacy and underlying mechanisms of binary combinations of five volatile organic compounds (VOCs) produced by lactic acid bacteria, specifically in their inhibition of A. flavus. This assessment was conducted through a comprehensive analysis, involving biochemical characterization and transcriptomic scrutiny. The results showed that VOCs induce notable morphological abnormalities in A. flavus conidia and hyphae. Furthermore, they disrupt the integrity of the fungal cell membrane and cell wall, resulting in the leakage of intracellular contents and an increase in extracellular electrical conductivity. In terms of cellular components, VOC exposure led to an elevation in malondialdehyde content while concurrently inhibiting the levels of total lipids, ergosterol, soluble proteins, and reducing sugars. Additionally, the impact of VOCs on A. flavus energy metabolism was evident, with significant inhibition observed in the activities of key enzymes, such as Na+/K+-ATPase, malate dehydrogenase, succinate dehydrogenase, and chitinase. And they were able to inhibit aflatoxin B1 synthesis. The transcriptomic analysis offered further insights, highlighting that differentially expressed genes (DEGs) were predominantly associated with membrane functionality and enriched in pathways about carbohydrate and amino acid metabolism. Notably, DEGs linked to cellular components and energy-related mechanisms exhibited down-regulation, thereby corroborating the findings from the biochemical analyses. In summary, these results elucidate the principal antifungal mechanisms of VOCs, which encompass the disruption of cell membrane integrity and interference with carbohydrate and amino acid metabolism in A. flavus.

Determination of twelve neonicotinoid pesticides in chili using an improved QuEChERS method with UPLC-Q-TOF/MS.

In this study, a QuEChERS method based on citrate was developed and utilized for the analysis of twelve neonicotinoid pesticides in fresh red chilies, fresh green chilies, and dried chilies, coupled with ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF/MS). In the sample preparation, acetonitrile containing 1% formic acid was used as the extraction solvent. Anhydrous sodium sulfate replaced the traditional anhydrous magnesium sulfate for water removal, effectively eliminating the issues of salt caking. Graphitized carbon black, octadecyl silica, and primary secondary amine were used as cleaning agents. The method showed good sensitivity, with the limits of quantification below 0.03 mg/kg for fresh chilies and below 0.15 mg/kg for dried chilies. Values of matrix effects ranged from -19.5% to 8.4%, and the recovery was 86.9% - 105.2%. The analytical method provided an effective tool for the high throughput detection of neonicotinoid pesticide residues in multiple chili matrices.

Isolation and evaluation of probiotics from traditional Chinese foods for aflatoxin B1 detoxification: Geotrichum candidum XG1 (yeast) and mechanistic insights.

Identifying aflatoxin-detoxifying probiotics remains a significant challenge in mitigating the risks associated with aflatoxin contamination in crops. Biological detoxification is a popular technique that reduces mycotoxin hazards and garners consumer acceptance. Through multiple rounds of screening and validation tests, Geotrichum candidum XG1 demonstrated the ability to degrade aflatoxin B1 (AFB1) by 99-100%, exceeding the capabilities of mere adsorption mechanisms. Notably, the degradation efficiency was demonstrably influenced by the presence of copper and iron ions in the liquid medium, suggesting a potential role for proteases in the degradation process. Subsequent validation experiments with red pepper revealed an 83% reduction in AFB1 levels following fermentation with G. candidum XG1. Furthermore, mass spectrometry analysis confirmed the disruption of the AFB1 furan ring structure, leading to a subsequent reduction in its toxicity. Collectively, these findings establish G. candidum XG1 as a promising candidate for effective aflatoxin degradation, with potential applications within the food industry.

Impact of salt content on Douchi metabolites: biogenic amines, non-volatile compounds and volatile compounds.

BACKGROUND: The excessive salt intake associated with Douchi has become a topic of controversy. Addressing this concern and enhancing its market competitiveness necessitates the application of salt reduction fermentation in Douchi. Therefore, to promote the application of salt reduction fermentation in Douchi, a comprehensive study was undertaken aiming to investigate the differences in biogenic amines, volatile compounds and non-volatile compounds in Douchi with varying salt content. RESULTS: The findings unequivocally demonstrate that salt hampers the formation of metabolites in Douchi. As the salt content increased, there was a significant decrease (P < 0.05) in the levels of total acid, amino-type nitrogen and free amino acids in Douchi. Notably, when the salt content exceeded 80 g kg-1, there was a substantial reduction (P < 0.05) in putrescine, lactic acid and malic acid levels. Similarly, when the salt content surpassed 40 g kg-1, ß-phenethylamine and oxalic acid levels exhibited a significant decline (P < 0.05). Furthermore, the results of E-nose and principal component analysis based on headspace solid phase microextraction gas chromatography-mass spectrometry revealed notable discrepancies in the volatile compound content between Douchi samples with relatively low salt content (40 and 80 g kg-1) and those with relatively high salt content (120, 160 and 200 g kg-1) (P < 0.05). By employing partial least squares discriminant analysis, eight distinct volatile compounds, including o-xylene, benzaldehyde and 1-octen-one, were identified. These compounds exhibited higher concentrations in Douchi samples with relatively low salt content (40 and 80 g kg-1). The sensory results showed that Douchi samples with lower salt content exhibited higher scores in the soy sauce-like and Douchi aroma attributes. CONCLUSION: In conclusion, this study significantly enhances our understanding of the impact of salt on metabolites in Douchi and provides invaluable insights for the development of salt reduction fermentation in this context. © 2024 Society of Chemical Industry.

Effects of synchronous intermissive multi-ultrasound and esterification dual modification on functionalities of starch and its emulsion stabilization ability.

Dodecenylsuccinic anhydride (DDSA) has been widely used to obtain amphiphilic starches. In this study, we investigated the functionalities of synchronous intermissive multi-ultrasound-assisted esterified starch. Compared to native starch (NS), it was deduced that multi-ultrasound-modified starch (US), esterified starch (ES), and multi-ultrasound-assisted esterified starch (UES) exhibited increased viscosities but reduced gelatinization temperatures and thermal stabilities. The viscoelastic moduli, retrogradation behaviors and hydrophobicity of the ES and UES species significantly altered. Moreover, the results of structural characterization suggested that esterification reduced the molecular weight and structural order of starch, whereas the intermissive ultrasonication treatment did not aggravate the structural disruption of ES. Additionally, compared with NS and US, the emulsification abilities of the ES and UES specimens were improved, leading to the desirable effect of stabilizing astaxanthin. Overall, this study provides a method for preparing amphiphilic starch, which can be exploited as a potential emulsifier and emulsion stabilizer for bioactive compounds.

Impact of aroma-enhancing microorganisms on aroma attributes of industrial Douchi: An integrated analysis using E-nose, GC-IMS, GC-MS, and descriptive sensory evaluation.

In order to enhance the aromatic profile of industrial Douchi, a comprehensive investigation was undertaken to assess the impact of aroma-enhancing microorganisms on the sensory attributes of Douchi. This evaluation utilized a combination of analytical techniques, including electronic nose analysis, gas chromatography-ion mobility spectrometry (GC-IMS), gas chromatography-mass spectrometry (GC-MS), and descriptive sensory analysis (DA). Both GC-IMS and GC-MS revealed significant changes in the volatile composition of Douchi following the addition of aroma-enhancing microorganisms (p < 0.05). Partial least squares-discriminant analysis (PLS-DA) identified benzaldehyde, benzene acetaldehyde, 3-octanone, and ethyl 2-methylbutyrate as significant differentiating volatile compounds. Additionally, compared to the control group, the sensory attributes of sourness in Douchi were significantly reduced (p < 0.001), while the attributes of wine-like and sweetness were notably enhanced (p < 0.05) when the ratio of G. candidum to C. versatilis was 1:1 (GCC group). By calculating the odor-activity values (OAVs) of key volatiles, it can be hypothesized that this aroma improvement of Douchi may be attributed to an increase in the typical volatiles (3-methyl-1-butanol, 1-octen-3-ol, 3-octanol, and 3-octanone) and ethyl 2-methylbutanoate with high OAVs (2340849.64 âˆ¼ 16695327.86), as well as to decreases in the musty acetophenone. In conclusion, the aroma profile of Douchi was significantly enhanced when G. candidum and C. versatilis were added at a ratio of 1:1. This study provides valuable insights into the development of aroma enhancers for improving the sensory profile of Douchi.

Functionality differences between esterified and pregelatinized esterified starches simultaneously prepared by octenyl succinic anhydride modification and its application in dough.

Octenyl succinic anhydride (OSA)-modified starches have gained widespread interest, but the modification can produce two starches with different states ignored. Herein, the two types of starches, esterified starch (ES) and pregelatinized esterified starch (PES), prepared by OSA modification were separated, and their structural and functional characteristics were comprehensively explored. Results showed that compared with native starch (NS), ES and PES exhibited high water-holding capacity, solubility, and swelling power and significantly decreased pasting temperature and thermal stability. Dynamic rheological tests illustrated that OSA modification changed the rheological behavior of starches. Fourier transform infrared spectroscopy confirmed that PES with higher degree of substitution showed more obvious ester carbonyl and carboxylate groups than ES. Laser confocal micro-Raman spectroscopy revealed that the short-range molecular order of ES, especially PES, decreased after modification. X-ray diffraction indicated that OSA modification disrupted the crystalline structure of starch, and that more amylose-lipid complex was formed in PES. Scanning electron microscopy showed that OSA modification eroded starchs surface and reduced its smoothness, and significantly disrupted PES integrity. ES and PES could be developed as food additives for retrogradation inhibition of dough. These results provide new insights into OSA modification and expand its functional application in foods.

Characterization of key bitter compounds in Idesia polycarpa var. vestita Diels fruit by sensory-guided fractionation.

Idesia polycarpa var. vestita Diels (I. vestita) has become a promising oil crop due to its easily digestible and highly nutritious fruit oil. However, the intense bitter taste of its fruit greatly limits its development and promotion in the food industry. Herein, five key bitter compounds from I. vestita fruit were isolated by sensory-guided fractionation and characterized using ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometer and nuclear magnetic resonance. The bitter taste of the identified compounds was subsequently validated by threshold tests and computational molecular docking. The bitterness threshold in water of idesin was the lowest (12.051 mg/L), and all bitter substances spontaneously bound to the bitter receptors hTAS2R16 and hTAS2R14, with a stronger affinity for the latter (approximately -6.5 - -9.0 kcal/mol). This is the first systematic study of bitter compounds in I. vestita fruit, providing a scientific basis for revealing the mechanism of bitterness formation and bitterness control.

New insights into the interaction between bamboo shoot polysaccharides and lotus root starch during gelatinization, retrogradation, and digestion of starch.

In this study, the interaction between bamboo shoot polysaccharides (BSP) and lotus root starch (LS) during gelatinization, retrogradation, and digestion of starch was investigated. The addition of BSP inhibited the gelatinization of LS and decreased the peak viscosity, valley viscosity, and final viscosity. Amylose leaching initially increased and then decreased with the increase in BSP addition. The apparent viscosity and viscoelasticity of LS decreased with the increase in BSP addition. Moreover, 3 % BSP increased the hardness and cohesiveness of LS gel, whereas 6 %-15 % BSP decreased them. In addition, 3 %-6 % BSP promoted the uniform distribution of water molecules in the starch paste, whereas the addition of 12 % and 15 % BSP resulted in the inhomogeneous distribution of the water. The retrogradation degree of LS gel gradually increased with the increase in BSP addition from 3 % to 6 %, whereas 9 %-15 % BSP restricted the short-term and long-term retrogradation of LS. After 12 % BSP was added, the RDS content reduced by 11.6 %, the RS content significantly increased by 75 %, and the digestibility of starch decreased. This work revealed the interaction between BSP and LS during starch gelatinization, retrogradation, and digestion to improve the physicochemical properties and digestive characteristics of LS.

Lotus starch/bamboo shoot polysaccharide composite system treated via ultrasound: Pasting, gelling properties and multiscale structure.

This study investigated the effects of ultrasound treatment on the physicochemical properties, digestion properties, and multiscale structure of a lotus root starch (LS) and bamboo shoot polysaccharide (BSP) composite system. It also preliminarily revealed the mechanism underlying the modification effect of ultrasound treatment. After 180-360 W ultrasound treatment, the viscosity, thixotropy, and gel viscoelasticity of the LS/BSP paste increased. However, treatment with the ultrasound power of 540 and 720 W decreased viscoelasticity. After 14 days of retrogradation, the hardness and cohesiveness of the LS/BSP gel increased under 180 and 360 W ultrasound treatment but decreased under 540 and 720 W ultrasound treatment. After 540 W ultrasound treatment, RDS content decreased by 17.2 % and resistant starch content increased by 32.5 %. After 180 min of in vitro digestion, the hydrolysis rate of LS/BSP decreased from 97.82 % to 93.13 % as the ultrasound power increased to 540 W. Ultrasound promoted the uniform dispersion of BSP in the starch paste and the movement, orientation, rearrangement, and aggregation of starch and BSP molecular chains. These effects further enhanced the interaction between BSP and starch, resulting in the formation of a dense paste structure with strong resistance to digestive enzymes. This work revealed the mechanism of the effects of ultrasound treatment on LS/BSP and found that 360-540 W ultrasound treatment could improve the physicochemical properties and digestion properties of LS/BSP.

Relationship between the Dynamics of Flavor Compounds and Microbial Succession in the Natural Fermentation of Zhalajiao, a Popular Traditional Chinese Fermented Chili Paste.

Zhalajiao, a traditional Chinese fermented food, is popular due to its unique flavor. Traditional Zhalajiao fermentation is closely related to flavor compounds production. However, the mechanisms underlying the formation of these crucial flavor components in Zhalajiao remain unclear. Here, we explored the dynamic changes in physical and chemical properties, microbial diversity, and flavor components of Zhalajiao at various fermentation times. In total, 6 organic acids, 17 amino acids, and 21 key volatile compounds were determined as flavor components. In Zhalajiao, Lactobacillus and Cyanobacterium were the main bacteria that were involved in the formation of crucial flavor compounds. Candida showed a significant correlation with 14 key flavor compounds during fermentation (p < 0.05) and was the main fungal genus associated with flavor formation in Zhalajiao. This research offers a theoretical foundation for the flavor regulation and quality assurance of Zhalajiao.

Inulin-whey protein as efficient vehicle carrier system for chlorophyll: Optimization, characterization, and functional food application.

Natural chlorophylls mostly found in vegetables such as spinach (Spinacia oleracea) could be employed as a possible substitute for synthetic colorants because of their intense green properties. However, the stability of natural chlorophyll is a major challenge to its utilization in the food industry. In this study, spray drying as an encapsulation technique was used to improve the stability of natural chlorophyll. Box-Behnken design was utilized to optimize the spray drying conditions for chlorophyll. Optimum conditions were given as inlet temperature, 132°C; inulin-to-whey protein isolate ratio, 61%:39%; pump rate, 25%, resulting in 92.3% encapsulation efficiency, 69.4% solubility, and -13.5 mV zeta potential at a desirability level of 0.901. The particle size, Carr index, bulk and tapped density, polydispersity index, and color showed satisfactory results. Crystallinity, endothermic peak melting temperature, and the enthalpy of chlorophyll-loaded microcapsules increased when compared to the blank microcapsules suggesting decreased hygroscopicity and enhanced thermal stability. In addition, the suitability of fabricated microcapsules using yogurt as a food model was assessed. Yogurt incorporated with chlorophyll-loaded microcapsules showed no significant pH modification with better apparent viscosity than control and sodium copper chlorophyllin (SCC) yogurt after 9 days of refrigerated storage. Based on the studied responses, the spray drying process could be optimized to achieve optimal output and product quality. PRACTICAL APPLICATION: Spray drying is a cheap and convenient approach for microencapsulating bioactive compounds such as chlorophyll. However, the physico-chemical and functional properties of the spray-dried microcapsules are influenced by operating conditions, such as inlet temperature, type and concentration of wall materials, and feed flow rate. Therefore, to maximize and obtain a superior quality of the final product, there is a need to optimize the spray drying process. The Box-Behnken design employed in this study could be utilized as an appropriate technique to design, enhance, and develop process parameters for the fabrication and better retention of the physico-chemical properties of spray-dried chlorophyll microcapsules.

Determination of multiple mycotoxins in chili powder using cold-induced liquid-liquid extraction and Fe3O4@MWCNTs-NH2 coupled with UPLC-Q-TOF/MS.

Food matrix interference is still a big challenge in analyzing multiclass mycotoxins. Herein, a novel cold-induced liquid-liquid extraction-magnetic solid phase extraction (CI-LLE-MSPE) coupled with ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q-TOF/MS) method was explored for the simultaneous determination of multiple mycotoxins in chili powders. Fe3O4@MWCNTs-NH2 nanomaterials were prepared and characterized, and the factors affecting the MSPE process were investigated. Based on this, the CI-LLE-MSPE-UPLC-Q-TOF/MS method was established for determining ten mycotoxins in chili powders. The proffered technique eliminated the matrix interference effectively and demonstrated strong linearity (0.5-500 µg/kg, R2 ≥ 0.999), high sensitivity (limit of quantification was 0.5-1.5 µg/kg), and the recovery was 70.6%-111.7%. The extraction process is simpler than conventional methods, as the adsorbent can be separated using magnets, and reusable adsorbents are beneficial in reducing costs. In addition, the method can provide a valuable reference for pretreatment procedures for other complex matrices.

Profile of Human Milk Phospholipids at Different Lactation Stages with UPLC/Q-TOF-MS: Characterization, Distribution, and Differences.

Human milk phospholipids are important for the regular growth and development of infants. Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was employed to qualitatively and quantitatively analyze 277 phospholipid molecular species in 112 human milk samples to obtain a detailed profile of human milk phospholipids along the lactation stage. MS/MS fragmentation patterns of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were characterized in detail. Phosphatidylcholine is the most dominant group, followed by sphingomyelin. PC(18:0/18:2), SM(d18:1/24:1), PE(18:0/18:0), PS(18:0/20:4), and PI(18:0/18:2) showed the highest average concentration among all of the phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol molecular species, respectively. The fatty acids attached to the phospholipid molecules were mainly palmitic, stearic, oleic, and linoleic acids, and the plasmalogens decreased along the lactation stage. The increase of sphingomyelins and phosphatidylethanolamines and the decrease of phosphatidylcholines are the key changes from colostrum to transitional milk; the increase of lysophosphatidylcholines and lysophosphatidylethanolamines and the continuous decrease of phosphatidylcholines are the vital changes from transitional milk to mature milk.

Effect of multiple-frequency ultrasound-assisted transglutaminase dual modification on the structural, functional characteristics and application of Qingke protein.

Qingke protein rich in restricted amino acids such as lysine, while the uncoordination of ratio of glutenin and gliadin in Qingke protein has a negative impact on its processing properties. In this study, the effect of multiple-frequency ultrasound combined with transglutaminase treatment on the functional and structural properties of Qingke protein and its application in noodle manufacture were investigated. The results showed that compared with the control, ultrasound-assisted transglutaminase dual modification significantly increased the water and oil holding capacity, apparent viscosity, foaming ability, and emulsifying activity index of Qingke protein, which exhibited a higher storage modulus G' (P < 0.05). Meanwhile, ultrasound combined with transglutaminase treatment enhanced the cross-linking degree of Qingke protein (P < 0.05), as shown by decreased free amino group and free sulfhydryl group contents, and increased disulfide bond content. Moreover, after the ultrasound-assisted transglutaminase dual modification treatment, the fluorescence intensity, the contents of α-helix and random coil in the secondary structure of Qingke protein significantly decreased, while the ß-sheet content increased (P < 0.05) compared with control. SDS-PAGE results showed that the bands of Qingke protein treated by ultrasound combined with transglutaminase became unclear. Furthermore, the quality of Qingke noodles made with Qingke powder (140 g/kg dual modified Qingke protein mixed with 860 g/kg extracted Qingke starch) and wheat gluten 60-70 g/kg was similar to that of wheat noodles. In summary, multiple-frequency ultrasound combined with transglutaminase dual modification can significantly improve the physicochemical properties of Qingke protein and the modified Qingke proteins can be used as novel ingredients for Qingke noodles.

In vitro bioaccessibility evaluation of chlorophyll pigments in single and binary carriers.

Chlorophyll was extracted and microencapsulated using different carrier agents. Subsequently, in vitro digestion was performed, and the bioaccessibility of chlorophyll in the different encapsulation systems was carried out. The zeta potential, particle size, and PDI were significantly modified after the micellarization of digested microcapsules. I-W-Chl presented with the highest total chlorophyll recovery and micellarization rate of 54% and 43%, respectively. In the aqueous micellar fraction, the different encapsulation systems had total chlorophylls, pheophytins, and pheophorbides ranging from 13 to 49%, 42 - 77%, and 3 - 22% respectively. The bioaccessibility of total chlorophyll pigment ranging from 7% to 20% is given in the following order: I-W-Chl > WPI-Chl > Z-Chl > Ca-Chl > SCChlV > SCChlC. The result established in this study shows that the carrier agent type could inhibit or mediate the bioaccessibility of chlorophyll with the potential to be an efficient delivery system for health promoting compounds.

Structural and physicochemical properties of the different ultrasound frequency modified Qingke protein.

There is a burgeoning demand for modified plant-based proteins with desirable physicochemical and functional properties. The cereal Qingke is a promising alternative protein source, but its use has been limited by its imperfect functional characteristics. To investigate the effect of ultrasound treatment on Qingke protein, we applied single- (40 kHz), dual- (28/40 kHz), and tri- (28/40/50 kHz) frequency ultrasound on the isolated protein and measured subsequent physicochemical and structural changes. The results showed that the physicochemical properties of proteins were modified following ultrasound treatment, and many of these changes significantly increased with increasing frequency. Compared with the native Qingke protein (control), the solubility, foaming activity, stability, and water or oil holding capacity of tri-frequency ultrasound modified Qingke protein increased by 43.54%, 20.83%, 20.51%, 28.9%, and 45.2%, respectively. Furthermore, ultrasound treatment altered the secondary and tertiary structures of the protein resulting in more exposed chromophoric groups and inner hydrophobic groups, as well as reduced ß-sheets and increasedrandom coils, relative to the control. Rheological and texture characterization indicated that the values of G' and G'', hardness, gumminess, and chewiness decreased after ultrasound treatment. This study could provide a theoretical basis for the application of multi-frequency ultrasonic technology for modification of Qingke protein to expand its potential use as an alternative protein source.