Hard-to-cook (HTC) is a textural defect that delays the softening of common bean seeds during cooking. While this defect is commonly associated with conventionally stored beans, soaking/cooking of beans in CaCl2 solutions or sodium acetate buffer can also prolong the cooking time of beans due to formation of Ca2+ crosslinked pectin retarding bean softening during cooking. In this study, the role of the cell wall-bound Mg2+/Ca2+ content and the degree of pectin methyl esterification (DM) was quantified, as important factors for bean texture-related changes stipulated in the pectin-cation-phytate hypothesis, the most plausible hypothesis of HTC development. Evalua-tion of texture changes during cooking of conventionally aged beans (35 degrees C and 83% RH for up to 20 weeks), beans soaked/cooked in CaCl2 solutions (0.01 to 0.1 M) or soaked in 0.1 M sodium acetate buffer (pH 4.4) revealed large bean-to-bean variations. Therefore a texture-based classification approach was used to better capture the relation between texture characteristics and cell wall polymer, in particular pectin, related changes. While cell wall-bound Ca2+ and pectin DM did not change/were not related to the texture variation during cooking of fresh beans, increased cell wall-bound Ca2+ and decreased pectin DM were associated with prolonged conventional storage of beans and their texture changes during subsequent cooking (due to pectin cross linking, retarding its solubilization during cooking). Exogenously added Ca2+ from pre-treating beans in CaCl2 solutions promoted to a great extent the cell wall-bound Ca2+ during soaking but even more so during cooking, com-plementing the harder texture associated with these beans during cooking (compared to conventionally stored and fresh beans). Similarly, free Ca2+ endogenously generated by phytase-catalysed phytate hydrolysis (beans treated by acetate buffer) promoted crosslinking of pectin by Ca2+ (cell wall-bound Ca2+), delaying softening of beans during cooking.

During adverse postharvest storage of Red haricot beans, the inositol phosphate content, particularly InsP6, decreased significantly, along with a significant increase in InsP5. Using a texture-based classification approach, the InsP6 content in cotyledons was shown an indicator for the extent of hard-to-cook (HTC) development during bean aging. This textural defect development was predominated by storage-induced InsP6 degradation, rather than phytate interconversions during soaking. Ca cations, released during storage, did not leach out significantly during subsequent soaking, suggesting that they were bound with the cell wall pectin in cotyledons, while Mg cations were mostly leached out into the soaking water due to their weak binding capacity to the pectin, and the cell membrane damages developed during HTC. Results obtained herein provide evidence for the pectin-cation-phytate mechanism in textural hardening (and its distribution after cooking) of common beans, and call for a more detailed Ca-relocation study during postharvest storage, soaking and cooking.

High hydrostatic pressure (HHP) and high-pressure homogenization (HPH) were applied to mango juice to explore their effects on gastric retention rate (G-CRR), bioaccessibility (BAC) of total and individual carotenoids, and the corresponding mechanisms from macroscopic to microscopic scales. Compared to the control, both HHP and HPH at 50 MPa had no significant effect on BAC and G-CRR, whereas HPH at 100 MPa significantly increased BAC by 44.33% and G-CRR by 11.84%. Further HHP treatments (particularly at 400 MPa) on the 100 MPa-HPH-pretreated samples significantly increased BAC by 71.37% and G-CRR by 24.24%. Violaxanthins/esters were less stable than carotenes in the stomach, resulting in lower bioaccessibility of violaxanthins/esters. G-CRR and BAC were negatively correlated with the viscosity and particle size of juice, whereas they were positively correlated with the solubility/dispersibility of carotenoids. In addition, pectin-carotenoid interactions may also be an important factor affecting the digestive fate of carotenoids in juice.Industrial relevance: High pressure processing (High hydrostatic pressure, HHP, and high pressure homogeniza-tion, HPH) is a non-thermal technique and its effect on the bioaccessibility of carotenoids in fruits and vegetables have attracted attention from researchers. Our research found that HPH and HHP combined treatment could decrease the particle size of mango juice, and increase the viscosity and turbidity as well as the bioaccessibility of carotenoids therein. This technology can be used to preserve the physical stability of mango juice and improve the nutritional value.

High hydrostatic pressure (HHP) (300/400/500 MPa for 5 min) and high pressure homogenization (HPH) (50/ 100 MPa for 1 pass) were applied to mango beverage to explore their effects on water soluble pectin (WSP) and bioaccessibility of total carotenoids (BAC), and the relationship between BAC and modified WSP. Compared to untreated sample, HPH at 50 and 100 MPa combined with/without HHP pronouncedly increased the WSP and galacturonic acid (GalA) concentrations in mango beverage and the molecular weight (Mw) of WSP, decreased the degree of methylesterification (DM) of WSP, and affected other structural indicators of WSP to various extent, while alone HHP slightly increased the GalA concentration in mango beverage and the Mw of WSP. These changes induced by high pressure processing were mainly due to mechanical release and solubilization of the pectin embedded in cell wall with higher Mw, shorter/fewer side chains, and lower DM. HPH had more pro-nounced effects on WSP than HHP due to stronger mechanical force. Compared to untreated sample, HPH at 50 MPa and HHP had no significant effect on BAC, while HPH at 100 MPa significantly increased the BAC by 32.22% and HPH (100 MPa) +HHP increased the BAC by 38.65%-76.32%. The BAC showed positive binomial correlations with GalA and WSP, and upwards binomial correlations with the Mw of WSP and viscosity of mango beverage. Moreover, a statistical negative correlation was found between the BAC and DM. Results highlighted the potential of high pressure processing to regulate the BAC by modifying WSP and affecting WSP-carotenoids interactions.

In this study, the role of soaking beans in a sodium citrate solution (a cation chelator) at pH = 4.4 and 41 degrees C in directing/improving the cooking behaviour of common beans was explored. The cooking behaviour of the presoaked red kidney beans was determined and the corresponding changes of phytate, minerals, starch, protein and pectin were quantified. Soaking beans in citrate buffer could accelerate softening of the beans during cooking in deionised water while subsequent cooking of beans in this buffer had a limited additional effect on softening compared to cooking in deionised water. Phytate hydrolysis during soaking in citrate buffer results in a release of Mg2+ and Ca2+. Both cations were leached into the soaking medium, higher amounts being observed for Mg2+ release to the soaking media because of the lower affinity of Mg2+ for pectin. It was observed that the pectin solubilisation rate in beans treated by sodium citrate buffer was positively correlated to bean softening. All of these results point out that soaking in a citrate buffer prohibits pectin Ca2+ cross linking therefore enhancing pectin solubilisation and thus increasing the bean softening rate constants during cooking, while starch and protein were not responsible for texture evolution.

To establish the HTC defect development, the cooking kinetics of seeds of ten bean accessions (belonging to seven common bean market classes), fresh and conventionally aged (35 degrees C, 83% RH, 3 months) were compared to those obtained after soaking in specific salt solutions (in 0.1 M sodium acetate buffer at pH 4.4, 41 degrees C for 12 h, or 0.01 M CaCl2 at pH 6.2, 25 degrees C for 16 h and subsequently cooking in CaCl2 solution, or deionised water). The extent of phytate (inositol hexaphosphate, IP6) hydrolysis was evaluated to better understand the role of endogenous Ca2+ in the changes of the bean cooking kinetics. A significant decrease in the IP6 content was observed after conventional ageing and after soaking in a sodium acetate solution suggesting phytate hydrolysis (release of endogenous Ca2+). These changes were accompanied by an increase in the cooking time of the beans. Smaller changes in cooking times after soaking in a sodium acetate solution (compared to conventionally aged beans) was attributed to a lower ionisation level of the COOH groups in pectin (pH 4.4, being close to pKa value of pectin) limiting pectin Ca2+ cross-linking. In beans soaked in a CaCl2 solution, the uptake of exogenous cations increased the cooking times (with no IP6 hydrolysis). The change in cooking time of conventionally aged beans was strongly correlated with the extent of IP6 hydrolysis, although two groups of beans with low or high IP6 hydrolysis were distinguished. Comparable trends were observed when soaking in CaCl2 solution (r = 0.67, p = 0.14 or r = 0.97, p = 0.03 for two groups of beans with softer or harder texture during cooking). Therefore a test based on the Ca2+ sensitivity of the cooking times, implemented through a Ca2+ soaking experiment followed by cooking can be used as an accelerated test to predict susceptibility to HTC defect development during conventional ageing. On the other hand, a sodium acetate soaking experiment can be used to predict IP6 hydrolysis of conventionally aged bean accessions and changes of cooking times for these bean accessions (with exception of yellow bean-KATB1).

Cell wall material was isolated from selected non-aged and aged Red haricot bean cotyledons using a texture -based classification approach. Pectin-depleted residual cell wall fractions were obtained by sequential pectin extraction and were characterized to investigate in situ cell wall related molecular changes upon ageing during adverse storage of the beans. Particularly, involvement of phenolic compounds in cell wall strengthening during the ageing process, resulting in the hard-to-cook defect, was evaluated. Results show that ageing induces sub-stantial changes at a cell-wall-structural level in the Aged sample compared to the Non-aged sample, with mainly vanillin, 4-hydroxybenzoic acid and 4-hydroxybenzaldehyde covalently bound with sugar side-chains of pectin and/or involved in lignification-like mechanisms. FT-IR spectroscopy coupled with chemometric analysis reveals that lignin-like phenolic-cell wall polymers, which are known to reinforce cell wall structure, are present in the cell wall polysaccharide network of the Aged sample, and are therefore contributing factors to the hard-to-cook development during Red haricot bean ageing.

Utilization of common beans is greatly hampered by the hard-to-cook (HTC) defect induced by ageing of the beans under adverse storage. Large bean-to-bean variations exist in a single batch of beans. Therefore, a texture -based bean classification approach was applied in this detailed study on beans with known textures, to gain in-depth insights into the role of the pectin-cation-phytate mechanism in relation to the texture changes during subsequent cooking of Red haricot fresh and aged beans. For the first time, a correlation between the texture (exhibited after cooking) of a single bean seed before ageing (fresh) and its texture after ageing was established. Furthermore, scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) based in situ cell wall associated mineral quantification revealed that the cell wall associated Ca concentration was signifi-cantly positively correlated with the texture of both fresh and aged cooked Red haricot bean cotyledons, with ageing resulting in a significant enrichment of Ca at the cell wall. These additional Ca cations originate from intracellular phytate hydrolysis during ageing, which was shown to affect the texture distribution of aged beans during cooking significantly. The relocation of the mineral cations from the cell interior to the cell wall occurs mainly during storage rather than subsequent soaking of the cotyledons. In addition, the pectin-cation-phytate hypothesis of HTC was further confirmed by demethylesterification of the cell wall pectin and increased pectin-Ca interactions upon ageing of the cotyledons, finally leading to HTC development of the cotyledon tissue.

To extend the applications of glutinous rice bran, a by-product of the glutinous rice processing industry, soluble dietary fibers (SDF) isolated from Chinese white (WSDF) and black (BSDF) glutinous rice bran were compared for their structures, physicochemical properties, and hypoglycemic activities in this study. Results showed that BSDF had higher glucose content while lower rhamnose, arabinose, xylose, and mannose contents, similar molecular weight, and a particular presence of anthocyanin compared to WSDF. Owing to the smaller particle size, higher viscosity, and more abundant network structures, BSDF had higher glucose adsorption capacity and retarding glucose diffusion ability than WSDF. The evaluations in vitro kinetics showed that addition of BSDF in starch led to a smaller glucose absorption rate constant and expected glucose index than WSDF, although BSDF showed lower α-amylase inhibitory ability. Interactions between the SDF and α-amylase, which were mediated by van der Waals force and hydrogen bond (WSDF-α-amylase) and hydrophobic interaction (BSDF-α-amylase), induced partial transformation of α-amylase from α-helix and β-sheet to β-turn and random coil. In summary, both WSDF and BSDF could be used as natural food additives for the reduction of postprandial blood glucose level and the enhancement of antioxidant activity in food products, while BSDF may show better efficacy.

In this study, two chemical bean seed hardening methods were used to investigate the changes in cooking behavior associated with Ca2+ transport and phytate hydrolysis to better understand their role in the pectincation-phytate hypothesis. The texture evolution of fresh and hardened red kidney beans was evaluated, hardening being induced by soaking or in a CaCl2 solution (0.01 M, 0.05 M, 0.1 M) or sodium acetate buffer (0.1 M, pH 4.4, 41 degrees C). The beans soaked in a CaCl2 solution at higher concentrations or in sodium acetate buffer for a longer time exhibited a delayed cooking behavior. This study also explored the bio-chemical changes (calcium content in different bean substructures, phytate content and the pectin degree of methylesterification (DM) in the cotyledons) occurring in the beans during chemical hardening and cooking. The Ca2+ concentrations in the whole beans and cotyledons of beans soaked and cooked in CaCl2 solutions significantly increased while inositol hexaphosphate IP6 content showed no significant changes. This indicates that the delayed texture drop in this case results from the influx of exogenous Ca2+ in the cotyledons and seed coats during cooking while the IP6 was not hydrolyzed and did not release endogenous Ca2+. For beans soaked in sodium acetate buffer, phytate profiling showed increased hydrolysis of IP6 with longer soaking time, suggesting the migration of endogenous Ca2+ released from phytate hydrolysis contributing to the delayed cooking of these beans. These results indicate that both an exogenous Ca2+ influx during soaking and cooking and an endogenous Ca2+ replacement resulting from phytate hydrolysis can play an important role in the hardening of beans. In neither of the cases, a significant change in pectin DM was observed during chemical hardening, therefore limiting the delayed cooking to the role of Ca2+ transport. The outcome of both cases is inline with the basic principles of the pectin-cation-phytate hypothesis whereby pectin DM changes are hardly involved and different mechanisms of release/transport are involved.

In this study, pectin changes during Red haricot bean storage under high temperature and high humidity conditions were investigated to understand the hard-to-cook (HTC) development from a microstructural point of view. First, to ensure repeatability of the microscopy results, a classification of the fresh and stored beans (aged at 35 degrees C and 83% relative humidity) into different hardening levels (the Non-aged, Aged and Very-hard aged sample) was performed based on the texture values of cooked half-cotyledons. Cell wall strength of the cotyledons was evaluated, showing that the aged samples (HTC seeds) exhibit stronger cell walls with more/stronger pectic cross-linkages than the Non-aged sample. After a sequential pectin extraction aiming at removing pectin fractions of different solubility, cell wall autofluorescence and immunolabeling of JIM7, LM9 and 2F4 epitopes in the residual materials were examined. Upon ageing, the samples exhibited an increased Ca2+-pectin and ferulic acid-pectin crosslinking, these pectic complexes being accumulated primarily at the intercellular spaces. The results suggest a contribution of both the pectin-cation-phytate hypothesis and the involvement of phenolic pectin crosslinks in HTC development at the cotyledon during storage of common beans.

In current studies, histopathologic method, Agilent GeneChip hybridization and Western blot were used to investigate the toxicity of acrylamide (AA) and glycidamide (GA) in male mouse livers. The histopathologic results demonstrated that AA and GA could cause oxidative damage to mouse liver. Middle dose of GA and AA (50 mg/kg b.w./day) could significantly up-regulate the expression of cytochrome P450, as well as genes related to oxidative injury, cancer and inflammation, and significantly down-regulate the expression of genes related to anti-apoptosis, antioncogene and fatty acid synthesis. Middle and high dose (75 mg/kg b.w./day) of GA and AA could both down-regulate the expression of hepatic anti-oncogene Bcl2 and up-regulate the expression of cancer-related gene Rad51 and EGFR protein. The expression of anti-oncogene P21 induced by AA and GA was decreased. Our current study demonstrated that the oxidative damage, immune injury and carcinogenicity of mouse liver samples could be induced by AA and GA at histopathological, entire genome and protein levels.

Furan, a typical food contaminant formed by heating process, is classified as a possible carcinogen to humans. Many factors lead to the formation of furan in food processing. In our present study, 3 potato varieties, white potato, sweet potato, and purple potato were selected to investigate the effect of thermal processing temperature and time on furan formation. The results showed that the formation of furan was highly correlated with frying temperature and time. Among the 3 potato varieties, sweet potato resulted in the highest furan concentration when fried at 200 °C for 5 min. In addition, the frying temperature and time also influenced the water activity and the color of the 3 kinds of potato slices, which had significant correlation with the formation of furan. Furan concentration decreased along with the increasing of water activity in the 3 potato varieties and the changes presented regression relationships. Meanwhile, there was an inverse correlation between furan content and color changes in the 3 potato varieties. The level of furan decreased as total color changes (ΔE) increased and the changes also presented regression relationships. These results could be used to estimate the possibility of furan formation in the 3 varieties of potato slices systems.

丙烯酰胺(acrylamide,AA)是一种重要的食品中内源性污染物,现已被国际癌症机构列为2A类人类可能的致癌物.环氧丙酰胺(glycidamide,GA)是AA重要的体内环氧化代谢产物,GA细胞毒性和遗传毒性远远强于AA.研究表明,大蒜素(allicin)作为大蒜鳞茎中的主要功能成分,对AA和GA引起的组织和细胞氧化损伤具有较强的保护作用.本文主要针对AA和GA的代谢毒性及大蒜素对AA和GA毒性的保护作用的研究进展进行了综述,为大蒜素(或大蒜提取物)在食品加工中作为预防AA和GA毒性的膳食补充剂提供了一定的理论基础.

Acrylamide is known to be a neurotoxic, genotoxic, and carcinogenic compound. Glycidamide has a close relationship to the toxic mechanism of acrylamide. In order to explore the toxic mechanism of acrylamide, we further discussed the effects of oral administration of allicin on glycidamide-induced toxicity by determining the hematological parameters like AST, ALT, LDH, BUN, creatinine, ROS, and 8-OHdG, and biochemical parameters such as MDA, MPO, SOD, GST and GSH in the kidney, liver, brain and lung of male and female mice for the first time. We found that the same dose of glycidamide had more toxic effects and damage effects to the mice compared to the previous study of acrylamide. It could markedly increase the level of AST, ALT, LDH, BUN, ROS, 8-OHdG, MDA, MPO while decrease the SOD, GST and GSH. However, our data showed the oral administered allicin with a concentration of 5, 10, and 20 mg/kg b.w./day could significantly decrease the damage indexes of AST, ALT, LDH, BUN, ROS, 8-OHdG, MDA, and MPO, while increase the antioxidant indicators of SOD, GST and GSH. Thus allicin could be used as an effective dietary supplement for the chemoprevention of glycidamide genotoxicity internally, and to prevent the tissue damage and toxicity induced by glycidamide.

Maize filaments (MF) are the outer thread-like part of corn, which are widely used in traditional and official medicine. In the current study, central composite design (CCD) was used to investigate the effect of process variables on polyphenols contents from MF by ultrasound-assisted extraction (UAE). Results showed that the obtained optimal UAE conditions were as follows: extraction power of 520.01 W, ethanol concentration of 61.08%, and a solvent-to-material ratio of 26.83 mL/g for polyphenols extraction. These experimental values under optimal conditions were consistent with the predicted values with polyphenols content of 7.1±0.015 mg/g. Sixteen phenolic compounds, including gallic acid, catechin, picatechin, hyperoside etc were identified in MF polyphenols extractions by HPLC-MS/MS method. The antioxidant activity of the MF polyphenols extractions were also studied, which showed that MF polyphenols extractions have excellent radical scavenging ability for ABTS radicals, •OH, DPPH radicals and •O2-, and 42.56 ± 1.24% of lipid oxidation inhibition.