Food research international (Ottawa, Ont.)最新文献

High-moisture (HM) extrusion is the dominant industrial process to create structured plant-based protein products that can be used for animal-free meat alternatives. Yet, the underlying mechanisms, such as phase separation, that govern structure formation in plant-protein extrudates, are still poorly understood. Current hypotheses require experimental data in order to be verified, but measurement techniques able to quantify phase-separated anisotropic protein extrudates are lacking, or have yet to be validated. In this study, Low-Field Time Domain (LF TD)-NMR and High-Field (HF) MRI techniques have been employed to unravel phase separation in HM extrudates of soy proteins. Results show that swelling with water enhances the ¹H NMR/MRI signal-to-noise ratio in the measurements and unveils the presence of lamellar regions, while freeze-thawing enhances phase separation due to freeze concentration. Phase separation could be quantified by the observation of two distinct populations by LF TD-NMR T₂ measurements. MRI images of dead-stop ribbon samples from interrupted HM extrusion revealed how the thickness of the aligned lamellar regions increases during passage of the protein melt through the cooling die. We conclude that TD-NMR can quantify phase separation, while spin-echo MRI can spatially resolve the lamellar structure conformation of HM extrudates. Thus, NMR and MRI are powerful techniques for non-invasively characterizing ex situ structure formation during HM extrusion, and for validating hypotheses on shear- and temperature-induced phase separation.

One commercial production run of Provolone del Monaco - a long-ripened pasta filata cheese - was followed up to the end of ripening for a total of 20 samples. 371 LAB isolates were subject to genetic characterization followed by 16S rRNA gene sequencing. The dominant species were Lacticaseibacillus casei/paracasei (19.4 %), Streptococcus macedonicus (19.1 %) and Enterococcus faecalis (13.2 %). Strains were screened for features of technological interest or safety relevance. Tyramine-producing cultures were quite common, above all within enterococci. By MALDI TOF Mass Spectrometry, one Lactococcus lactis and one Enterococcus faecium strain proved to be bacteriocin producers. Four further cheese wheels from the same production run at 623 days of ripening were evaluated for volatile organic compounds, biogenic amines, and bacterial community by metagenomic sequencing. Three individual wheel samples shared a rather similar microbiome with Lactobacillus delbrueckii and Streptococcus thermophilus as the most represented species, while the fourth wheel appeared wholly different being dominated by Lentilactobacillus buchneri and St. infantarius. Additionally, this sample had the greatest content of biogenic amines and a different VOCs composition. Given the variance seen among cheese wheels processed and ripened under the same conditions, the search for adjunct cultures in the production of this cheese seems to be of utmost importance.

Resveratrol (RVT), a plant antitoxin, plays an important role in plant resistance against pathogens. While nitric oxide (NO) as an essential signaling factor in disease resistance enhancement is well documented, the potential molecular interplay RVT and NO in postharvest tomato fruit defense against Botrytis cinerea (B.cinerea) still needs exploration. In this study, exogenous RVT reduced gray mold caused by B.cinerea in tomato fruit, with 20 μM being the most effective. Tomato fruit were treated with 20 μM RVT enhanced resistance against B.cinerea, as indicated by reduced symptoms of disease and improved activity of disease resistance related enzymes (PAL, PPO and CHI). In addition, RVT treatment improved the expression of SlPR1, SlLoxd and SlMYC2, and promoted the accumulation of plant hormone IAA and ABA, but reduced the expression of SlNPR1 and the level of GA3. More importantly, the combined treatment of NO donor (SNP) and RVT notably enhanced disease resistance compared to RVT or SNP single treatment. However, the combination of NO inhibitor (L-NNA) and RVT treatment even reduced the positive effect of RVT. Meanwhile, the expression of SlPR1, SlLoxd and SlMYC2 and the accumulation of IAA and ABA in RVT + SNP treated fruit were higher than those in the RVT or SNP single treatment. Thus, our data demonstrate that RVT and NO synergistically enhance resistance against B. cinerea in tomato fruit by regulating phytohormones.

While heat treatment is a conventional method for the gelation of alkaline-extracted walnut protein isolates (AWPI), it can limit the incorporation of heat-sensitive ingredients. This study explored a novel approach to fabricate cold-set gels from epigallocatechin-3-gallate (EGCG) conjugated AWPI (AWPI-EGCG). EGCG conjugation effectively inhibited the thermal gelation of AWPI while promoting the formation of soluble aggregates upon heat treatment. AWPI-EGCG cold-set gels were then successfully fabricated through acidification with glucono-δ-lactone (GDL). The rheological study revealed that the storage modulus and yield stress of the cold-set gels were positively correlated with the GDL concentration and the EGCG conjugation degree. However, higher concentrations of GDL were associated with the reduced yield strain of the gels. Texture analysis indicated an increase in gel hardness with increasing GDL concentration, accompanied by a decrease in springiness. Microstructural examination by scanning electron microscopy revealed that the AWPI-EGCG cold-set gels with 0.3 % GDL exhibited smaller pores with thinner and smoother internal walls, while those with 0.9 % GDL exhibited relatively larger pores with thicker and denser walls. In addition, the AWPI-EGCG cold-set gels showed promising quercetin encapsulation capacities and controlled release properties.

Mesona blume straw (MBS) is a class of high-fiber, low-value Mesona blume's colloid by-products. We investigated the changes in dietary fiber (DF), triterpenoid, and polysaccharide contents of fermented Mesona blume straw (FMBS) by Ganoderma lucidum (GL), we also examined the effect of adding FMBS at different levels (0 %, 5 %, 10 %, and 15 %) on cooking quality, texture, in vitro starch digestibility and in vitro fermentation broth properties and gut bacteria of noodles. The results showed that after fermentation, soluble dietary fiber (SDF) increased by 16.3 % and insoluble dietary fiber (IDF) decreased by 25.67 % in MBS. Adding FMBS at 5 % and 10 % significantly enhanced the cooking quality and texture of noodles while preserving the gluten structure. FMBS limited noodles starch hydrolysis with 24.17 % increase of resistant starch (RS) and 13.6 decrease of predicted glycemic index (pGI). After in vitro fermentation of FMBS noodles, the short-chain fatty acids (SCFAs) levels and relative abundance of probiotics increased. In this study, it was found that the modification of MBS and improvement of noodle quality was significant.

Eurotium cristatum is the primary fungus in Fu brick tea (FBT) and plays a crucial role in its special flavor. This study investigated the effect of inoculation with different E. cristatum strains (i.e., ZJ, GX, GZ, HN, and SX) on the microbial communities and volatile organic compounds (VOCs) of FBT. A total of 113 VOCs were identified in all samples, with the concentration of VOCs (alcohols, aldehydes, and ketones) significantly higher in GXE FBT than in other samples. The core VOCs of GXE (19), GZE (16), HNE (19), SXE (15), and ZJE (13) FBT were identified using orthogonal partial least squares discriminant analysis and relative odor activity value (ROAV) analysis. Methional (a27), butanal (a41), 1-octen-3-one (a69), and ethyl acetate (a77) were key markers for inoculated FBTs, and 1-octen-3-ol, dimethyl disulfide, and acetoin-M were the specific markers of HNE. Linalool and (E)-2-octenal were particularly prominent in GXE, and isoamyl acetate-D was an important aroma component of GZE. Differences in microbial diversity were observed among the different inoculated fermented FBTs, and E. cristatum inoculation remarkably influenced the richness and diversity of bacterial communities. The VOCs were closely associated with fungi and bacteria, and 19 potentially dominant microorganisms (10 fungal and 9 bacterial genera) correlated with VOCs were identified. Among them, Aspergillus (fungi) and Pseudomonas (bacteria) exerted the greatest role. The FBT inoculated with E. cristatum from ZJ had the highest content of theaflavins and theabrownins, which intensified the red and yellow colors of the tea. E. cristatum greatly decreased the free amino acids and fatty acids, contributing to the aroma formation of FBT. Therefore, inoculating FBT with E. cristatum remarkably influenced the microbial communities and improved its flavor profile. This work provides a theoretical foundation on the role of E. cristatum in the formation and regulation of FBT flavor.

A wide range of protein and polysaccharide structures have been applied for the encapsulation of bioactive compounds. In this research, a hydrogel was prepared using mung bean protein isolate and κ-carrageenan as a copolymer. The obtained hydrogel was used for encapsulating propolis at 1 % and 3 % (w/v). The rheological properties and the elasticity of the hydrogel samples with different percentages of propolis was investigated to determine resilience of the hydrogel. The textural analysis illustrated that propolis encapsulation does not change the hydrogel's chewiness, adhesiveness, and hardness. Fluorescence spectroscopy, FTIR, and SDS-PAGE techniques were used to determine the interactions between κ-carrageenan and mung bean protein isolate. The results suggested that electrostatic interactions and covalent bindings are responsible for gel preparation. Hydrophobic interactions contributed to propolis encapsulation. The quenching of aromatic amino acid residue and the clear propolis peak observed in fluorescence spectroscopy represented the role of hydrophobic interactions in encapsulation and gel formation. The water holding capacity (WHC) of >99 % and syneresis of <0.03 % of κ-carrageenan and mung bean protein isolate hydrogel represented an efficient structure of the hydrogel. The peak shifts of κ-carrageenan and mung bean protein isolates illustrated in the FTIR spectra were in line with SDS-PAGE results and fluorescence spectroscopy. The significantly increased encapsulation efficiency of >99 %, release rate of >50 %, and antioxidant activity of propolis encapsulated in κ-carrageenan and mung bean protein isolate suggested that the κ-carrageenan and mung bean protein isolate hydrogel is a potential delivery system and carrier for hydrophobic bioactive compounds, especially propolis.

The impact of food design parameters on digestion is mostly studied using static in vitro digestion models. In this work, the complexity of the static model was gradually increased, by implementing several dynamic gastric reactor conditions, i.e., gradual (i) acidification, (ii) pepsin addition, and (iii) emptying, as well as (iv) saliva in the oral phase. As a relevant case study, starch and protein digestion was studied in lentil cotyledon cells under these conditions. Implementation of these dynamic parameters affected gastric proteolysis, linked to the pH-dependence of pepsin, and amylolysis, linked to the pH-dependence of salivary amylase activity. Though gastrointestinal hydrolysis kinetics were affected by the applied simulation conditions, similar levels of starch and protein digestion were generally reached at the end of the simulated digestion. Salivary amylase was not completely inactivated at the low gastric pH conditions, resulting in significantly higher levels of small intestinal starch digestion upon saliva inclusion. Gastric emptying significantly affected macronutrient hydrolysis kinetics. In that regard, an approach separately considering gastric samples taken upon different gastric emptying times should be preferred over the pooling of gastric samples before simulating small intestinal digestion.

This study examined the interfacial evolution of individual bile salts (BSs) and their blends with phosphatidylcholine (BS/PC) to simulate the complex behaviour of human bile (HB) during lipolysis at the triglyceride/water interface. Using adsorption and desorption cycles, mimicking exposure to small intestinal fluids, we demonstrate that the interfacial behaviour of real HB can be replicated using simple mixtures of BSs and PC. Interfacial tension (IFT) measurements after lipolysis and desorption showed no significant differences (P > 0.05) between HB samples and BS/PC mixtures across the total BS concentrations analysed (2.23-7.81 mM). However, individual BSs without PC yielded significantly different IFT results (P < 0.01) compared to HB, highlighting the importance of phospholipids. Dilatation rheology further emphasised the need for accurate phospholipid representation in bile models. Our results suggest that phospholipids in HB and in BS/PC systems enhance resistance to desorption, potentially affecting lipolysis. This is important, as current in vitro digestion models often replicate only intestinal BS concentrations to mimic the behaviour of HB in the intestinal lumen. Furthermore, the specific composition of BSs in HB appears less critical than the overall BS and phospholipid contents, suggesting that the kinetics of triglyceride digestion is influenced by the combined luminal concentrations of these components. These findings have significant implications for understanding the role of bile in digestion and offer insights for designing more accurate in vitro models to study the gastrointestinal behaviour of food emulsions and lipid-based delivery systems.

In this study, two polysaccharides were isolated from the flesh and peel of wampee, termed as PWP-F and PWP-P respectively, and their structural characteristics, in vitro antioxidant and hypoglycemic activities and digestion were investigated. Results indicated the molecular weight of PWP-F was higher than that of PWP-P and they were both mainly composed of galactose and arabinose. Both polysaccharides exhibited α-type and β-type glycosidic linkages based on FTIR analysis. NMR spectroscopy revealed that PWP-F mainly consisted of α-Araf-(1→, →3,5)-α-Araf-(1→, →2,5)-α-Araf-(1→, →4) → β-Galp-(1 → and α-GalpA-(1→, while PWP-P was composed of α-Araf-(1→, →3)-α-Araf-(1→, →5)-α-Araf-(1→, →3,6) → β-Galp-(1→ and α-GalpA-(1→. Scanning electron microscopy showed that PWP-P had more porous surface structure compared to PWP-F. Moreover, PWP-P exhibited superior antioxidant activity and significant inhibition of both α-glucosidase and α-amylase compared to PWP-F. Specifically, PWP-P demonstrated mixed inhibition against α-glucosidase and α-amylase. In vitro digestion results showed the molecular weight, polysaccharide and reducing sugar content of PWP-F and PWP-P decreased after simulative gastrointestinal digestion. Overall, PWP-P has great potential as a kind of new antioxidant and hypoglycemic agent.