Humidity-controlled heat treatment of fresh spinach noodles for color preservation and storage quality improvement.

The high sensitivity to color browning during room-temperature storage was a significant factor in limiting the development of fresh spinach noodles (FSN). The practice of humidity-controlled heat treatment (HCHT) at varying temperatures, relative humidity, and time was carried out to limit enzyme activity and improve the quality of FSN. Results showed that HCHT could maximize the color preservation of fresh spinach noodle quality while effectively inactivating polyphenol oxidase and the yeasts, and mold count in FSN during storage was almost undetectable after mild conditions (80 °C). The hardness and chewiness of HCHT noodles were significantly increased, but the free sulfhydryl content was reduced. At 80 °C, 90 %, 5 min, protein structural aggregation was found in the microstructure of HCHT fresh spinach noodles. HCHT also caused partial gelatinization, as evidenced by the decrease in starch gelatinization enthalpy from 5.49 to 4.77 J/g, although the gelatinization degree of FSN was comparatively low.

Efficacy of cecal retroflexion observed on adenoma missing of ascending colon during colonoscopy: A prospective, randomized, pilot trial.

BACKGROUND: Although colonoscopic retroflexion has been proved effective in reducing missed adenomas, there is still a lack of comprehensive and in-depth research focused on the ascending colon. We aimed to conduct a randomized controlled trial and tandem colonoscopy to investigate whether cecal retroflexion observed during colonoscopy can reduce missed adenomas in the ascending colon. METHODS: Men and women required to be between 45 and 80 years of age were screened for enrollment in the trial. Patients were randomly assigned according to a 1:1 ratio to either the trial group or control group. Patients in the trial group underwent 2 forward examination and a cecal retroflexion observed in the ascending colon, while patients in the control group underwent only 2 forward examinations in the ascending colon. The primary outcome was adenoma miss rate. The secondary outcomes contained adenoma detection rate, polyp miss rate, polyp detection rate, insertion time and withdrawal time. Differences between groups in the primary outcome and in the other categorical indicators were tested using chi-squared test and Fisher exact test. For the comparison of continuous outcomes, the Student t test was applied. RESULTS: A total of 60 subjects were eligible for the study between April to June 2020, of which 55 were randomized and eligible for analysis (26 to the control group and 29 to the trial group). The characteristics of patients were no significant differences statistically between the trial group and the control group. Similarly, the characteristics of the colonoscopy procedures included cecal insertion distance, the length of cecum and ascending colon, insertion time, withdrawal time, quality of bowel preparation, numerical rating scale for pain, polyps detected, and adenomas detected, and there were no significant differences statistically between the 2 groups (P = .864, P = .754, P = .700, P = .974, P = .585, P = .835, P = .373, P = .489). The characteristics of the polyps were also no significant differences statistically between the 2 groups. CONCLUSION: This pilot trial failed to show benefit of cecal retroflexion observed on adenoma missing of ascending colon during colonoscopy; however, further conclusions require a prospective study with a higher level of evidence. (NCT03355443).

Re-recognition of BMPR1A-related polyposis: beyond juvenile polyposis and hereditary mixed polyposis syndrome.

Background: Bone morphogenetic protein receptor type 1A (BMPR1A) is responsible for two individual Mendelian diseases: juvenile polyposis syndrome and hereditary mixed polyposis syndrome 2, which have overlapping phenotypes. This study aimed to elucidate whether these two syndromes are just two subtypes of a single syndrome rather than two isolated syndromes. Methods: We sequenced the BMPR1A gene in 186 patients with polyposis and colorectal cancer, and evaluated the clinicopathological features and phenotypes of the probands and their available relatives with BMPR1A mutations. Results: BMPR1A germline mutations were found in six probands and their three available relatives. The numbers of frameshift, nonsense, splice-site, and missense mutations were one, one, two, and two, respectively; two of the six mutations were novel. Typical juvenile polyps were found in only three patients. Two patients had colorectal cancer rather than any polyps. Conclusions: Diseases in BMPR1A germline mutation carriers vary from mixed polyposis to sole colorectal cancer, and typical juvenile polyps do not always occur in these carriers. The variety of phenotypes reflected the features of BMPR1A-mutation carriers, which should be recognized as a spectrum of one syndrome. Genetic testing may be a good approach to identifying BMPR1A-related syndromes.

Succeeded high-temperature acid hydrolysis of granular maize starch by introducing heat-moisture pre-treatment.

Acid hydrolysis is a crucial method for modifying granular starch, but it is often conducted at low temperatures (below 55 °C) for an extended period of time to prevent crystallinity loss. The high-temperature acid hydrolysis (HTAH) behavior of heat-moisture treated (HMT) starch at 69 °C was investigated for the first time. The crystalline structure of starch was enhanced by HMT, confirmed by its rheological, thermal, and infrared Fourier transform spectroscopy results. The amorphous structure of HMT starch was preferentially hydrolyzed with high reactivity, related to a fast hydrolysis stage (4.17 × 10-2 min-1). And the crystalline flakes were separated from starch granules, accompanied by strengthened molecular interactions. HMT starch was transformed from 16.98 µm granules to 158 nm thick and 2.57 µm broad flakes with a 6.40 % increase in crystallinity after 40 min of hydrolysis. For native starch, the HTAH destroyed the crystalline structure due to gelatinization, resulting mainly gelatinous aggregates. These evidenced that the hydrolysis of granular starch was successfully performed at a relatively high temperature by introducing heat-moisture pre-treatment. This study could provide a novel perspective on the combination of increasing temperature and pre-treatment for granular starch hydrolysis intensification design, as well as a strategy for efficiently preparing small-sized crystalline starch, which has promising applications in Pickering emulsion and material filler.

Fabrication and stabilization mechanisms of Pickering emulsions based on gliadin/arabinoxylan complexes.

In the present work, the Pickering emulsions with enhanced oxidation stability were fabricated using gliadin (G)/arabinoxylan nanoparticles (GANPs). The influence of different G/AX ratios on the properties of GANPs and corresponding physicochemical characteristics of Pickering emulsions were investigated. Results indicated that the droplet size and ζ-potential of Pickering emulsions declined with the decrease of G/AX ratios. Pickering emulsion with the smallest G/AX ratio (1:4) exhibited excellent oxidative and coalescence stability due to the formation of viscoelastic gel network, which was supported by confocal laser scanning microscopy (CLSM) images. Furthermore, the increase of salt ions in a lower concentration (0-0.2 M) was conducive to the flocculation of the droplets, while further increasing the NaCl concentration impaired the emulsion stability. Such elements revealed that G/AX complex is a promising stabilizer of Pickering emulsions with prominent antioxidant activity, which have favorable potential applications in protecting the functional properties of polyunsaturated fatty acids (PUFAs).

Effect of freeze-thaw cycles on the physicochemical properties and frying performance of frozen Youtiao dough.

The impact of freeze-thaw cycles on the physicochemical properties and frying performance of frozen Youtiao dough with chemical leavening agent was investigated. The specific volume of Youtiao made from frozen dough decreased by 66% after 4 freeze-thaw cycles. Meanwhile, the hardness and puncture force showed increasing trends, and the fibrous structure became unclear. The extensibility, storage modulus (G') and loss modulus (G'') of frozen Youtiao dough decreased during freeze-thaw cycles, while the creep compliance increased. Changes in rheological properties demonstrated that frozen Youtiao dough was more deformable and its strength was weakened. Moreover, the sodium dodecyl sulfate (SDS) extractable protein and free sulfhydryl content increased, revealing that protein was depolymerized. The loose structure with large pores and fractured protein network were observed by micromorphology. Freeze-thaw cycles had a detrimental effect on the Youtiao quality, which was related to the deterioration of rheological properties and protein structure of frozen Youtiao dough.

Metabolomics analysis of freeze-thaw tolerance enhancement mechanism of ε-poly-l-lysine on industrial yeast.

Antimicrobial polycationic peptide ε-poly-l-lysine (ε-PL) enhanced the freeze-thaw tolerance of industrial yeast; the enhancement mechanism of ε-PL on yeast was studied. Results showed that a ε-PL coating was observed in ε-PL-treated yeast. After 4 times of freeze-thaw, the cell viability, glycerol content, and CO2 production of 0.6 mg/mL ε-PL-treated yeast were higher than those of untreated yeast, specifically, the cell viability of ε-PL-treated yeast was 87.6%, and that of untreated yeast was 68.5%. Metabolomic results showed that the enhancement mechanism of ε-PL on yeast was related to the promotion of cell membrane-related fatty acid synthesis pathways before freeze-thaw treatment, and the promotion of trehalose biosynthesis and glycerophospholipid metabolism pathways after freeze-thaw. Furthermore, ε-PL induced inhibition of the tricarboxylic acid cycle, resulting in a longer stationary phase at the beginning of the freeze-thaw and ultimately providing a higher level of freeze-thaw stress tolerance than untreated yeast.

Influence of the Addition of Extruded Endogenous Tartary Buckwheat Starch on Processing and Quality of Gluten-Free Noodles.

Extruded starch could be used as a thickener for food processing due to its pre-gel properties. This study aimed to explore the influence of the addition of extruded endogenous Tartary buckwheat starch (ES) on the process and quality of gluten-free noodles. ES was mixed with Tartary buckwheat flour in different proportions (10-40%) to prepare the blended flour and noodles. When the content of ES was increased, the swelling power of blended flour at 90 °C had no significant changes, and the decrease in peak viscosity of blended flour was reduced. This indicated that the high-content ES could afford better thermal stability for blended flour and inhibit the swelling ability. The higher level of ES was beneficial to the formation and stabilization of dough, and the improvement of noodle tensile strength. Furthermore, there was no difference in cooking loss between noodles with 30% and 40% ES addition. The microstructure and water distribution of the noodles prepared by blended flour indicated that the gel-entrapped structure organized by the higher content ES could be closely related to the above results. In conclusion, higher ES could contribute to improving the processing properties and quality of noodles.

Changes of lipids in noodle dough and dried noodles during industrial processing.

This study investigated the changes of lipids during the industrial preparation of noodle dough and dried noodles, including the hydration, sheeting, and drying processes. The results showed that industrial processing markedly influenced the stability of lipids during the preparation of dried noodles. The contents of total free fatty acids, polyunsaturated fatty acids, and free lipids were reduced, while peroxide values increased during the hydration and sheeting processes, showing the instability of lipids. The increase in lipid oxidation may have been due to the activation of lipoxygenase. Although its activity declined by 45.7% in the hydration process compared to that of the native wheat flour (198.5 ± 20.4 U/g/min), the residue activity should have been high enough to oxidize lipids. Interestingly, lipase activity remained relatively stable. In addition, an obvious increase of carbon-centered free radicals was observed during the entire processing. In conclusion, the industrial processing, especially the hydration process, markedly changed the lipid profile and promoted lipid oxidation during the preparation of dried noodles. PRACTICAL APPLICATION: The present study showed the positive relationship between endogenous lipid degrading enzymes and the degradation of lipids and elucidated the role of industrial processing on lipid stability in noodle dough and dried noodles. The results of the present study will also help us to understand more about the sensory quality of dried noodles during preparation, as well as to develop high quality of wheat-based food products.

The effects of extruded endogenous starch on the processing properties of gluten-free Tartary buckwheat noodles.

The lack of gluten in Tartary buckwheat has always been the main limiting factor of their development. This paper explored how to improve the processing quality of gluten-free Tartary buckwheat noodles (GF-TBNs) by introducing extruded starch into Tartary buckwheat flour (TBF) and the underlying mechanism was also elucidated. Extruded Tartary buckwheat starch (ETBS) was obtained under different extrusion conditions. The thermal properties, molecular weight, and viscosity of ETBS were examined to determine the key parameters closely related to the water distribution and rheological properties of the dough sheet, and tensile properties of GF-TBNs. The results showed that ETBS with a low molecular weight and high viscosity contributed greatly to the GF-TBNs with good tensile properties. It is proposed that ETBS with a low molecular weight and high viscosity might form a gel-entrapped network inside GF-TBNs, which was confirmed by the morphology of GF-TBNs.

Thermal-aggregation behavior of gluten in frozen dough induced by ε-poly-L-lysine treated yeast.

ε-poly-L-lysine treated yeast (PTY) helps to enhance the freeze-thaw tolerance of frozen dough. This study explored the effect of PTY on the aggregation and the gas-retention of frozen dough after steaming for 2, 5, 10, and 20 min. Gas-cell images showed that PTY reduced the loss of gas-retention ability caused by 4 times of freeze-thaw. The results of sodium dodecyl sulfate extractability and subunit distribution of gluten showed that, after the same heat time, frozen dough with PTY has higher degree of covalent crosslinking with better aggregation ability of α-, γ-gliadin, and low molecular weight glutenin subunits than frozen dough with yeast. Chemical analysis and chain morphology results demonstrated that the levels of acidity, NH2, and free sulfhydryl in dough were decreased, and the protein molecules aggregated into longer chains when using PTY instead of yeast, indicating that PTY reduced acid-mediated hydrolysis and increased the disulfide bonds-mediated gluten polymerization.

Effect of NaHCO3 and freeze-thaw cycles on frozen dough: From water state, gluten polymerization and microstructure.

This study investigated the influence of NaHCO3 on the water state, gluten polymerization, microstructure and quality of frozen steamed bread dough during freeze-thaw cycles. Results showed that the steamed bread made from alkaline (0.4% NaHCO3) frozen dough possessed a larger specific volume and smaller hardness after 4 freeze-thaw cycles, than the non-alkaline dough group. The addition of NaHCO3 slowed the increase of freezable water content and water mobility of dough during freeze-thaw cycles, and the high amount of NaHCO3 (0.4%-1%) showed the great effect. Compared with non-alkaline dough, the sodium dodecyl sulfate extractable protein proportion and free sulfhydryl level of alkaline dough increased less after freeze-thaw cycles, indicating a strengthened freeze-thaw tolerance of alkaline dough. Based on microstructure image and corresponding protein network analysis (PNA) results, the protein area and total protein length in alkaline dough remained at a higher level than non-alkaline group after 4 freeze-thaw cycles.

Effect of Humidity-Controlled Dehydration on Microbial Growth and Quality Characteristics of Fresh Wet Noodles.

Humidity-controlled dehydration (HCD) was innovatively applied in this paper to control the growth of microorganisms in fresh wet noodles (FWN). Effects of HCD treatment with different temperatures (40, 60 or 80 °C), relative humidity (RH, 50%, 70% or 90%) and treatment time (5-32 min) on the total plate count (TPC), the shelf-life, and qualities of FWN were investigated. The results showed that HCD reduced the initial microbial load on the fresh noodles and extended the shelf-life up to 14-15 days under refrigeration temperature (10 °C). A 1.39 log10 CFU/g reduction for the initial TPC was achieved after HCD treatment at the temperature of 60 °C and RH of 90%. HCD with higher RH had a more positive influence on quality improvement. The L* values, the apparent stickiness, and the cooking properties of the noodle body were improved by HCD while good sensory and texture quality of noodles were still maintained after the dehydration process.

Influence of protein type, content and polymerization on in vitro starch digestibility of sorghum noodles.

The impacts of protein type, content and polymerization on in vitro starch digestibility of cooked sorghum noodles were investigated. Results showed that addition of exogenous proteins decreased the starch hydrolysis rate. The noodles added wheat protein (WP) exhibited the highest amount of resistant starch, followed by whey protein isolate (WPI) and egg white protein (EWP). In each group, the hydrolysis kinetic parameters were the lowest when protein addition amounts were 5% WP, 3% EWP and 3% WPI, respectively. These changes were ascribed to the interactions of starch-proteins and protein-proteins, as proved by the enhancement of protein polymerization and starch short-range structure. The increase of protein polymerization degree induced by disulfide cross-links reduced the starch digestion rate of noodles. Additionally, the confocal laser scanning microscope observations demonstrated that the strengthening of protein network had a positive effect on decreasing starch digestibility by preventing the accessibility of enzymes to starch.

Influence of ε-poly-l-lysine treated yeast on gluten polymerization and freeze-thaw tolerance of frozen dough.

The effects of ε-poly-l-lysine (ε-PL) treated yeast on gluten polymerization of frozen dough and quality of steamed bread after freeze-thaw cycles were investigated. Compared with steamed bread made from frozen dough containing ε-PL and untreated yeast (PUTY) or only untreated yeast, steamed bread made from frozen dough containing ε-PL treated yeast (PTY) had a larger specific volume, lower hardness and more porous. A dynamic rheological and scanning electron microscopic analysis demonstrated that using PTY instead of yeast could reduce dough elasticity and damage protein network after freeze-thaw cycles. Lower sodium dodecyl sulfate (SDS) soluble polymeric proteins and monomeric proteins, and higher SDS insoluble proteins were found in frozen dough containing PTY, which indicates a reduced depolymerization of gluten proteins after freeze-thaw cycles. After 4 freeze-thaw cycles, the lower glutathione and free sulfhydryl in dough containing PTY indicate that the interchain disulfide bonds between proteins were preserved.

Effect of thermal treatments on in vitro starch digestibility of sorghum dried noodles.

In this paper, sorghum grains were pretreated by roasting (RT), microwave (MW), stir-frying (SF) and heat-moisture treatment (HMT). The effects of pretreated sorghum grains on in vitro starch digestibility of sorghum dried noodles made from sorghum and wheat flour were investigated. The results showed that HMT treated noodles contained the highest amount of resistant starch (RS) and the lowest amount of rapidly digestible starch (RDS). The hydrolysis kinetic parameters and estimated glycemic index (eGI) decreased in all of the treated samples. The treated starches had lower molecular weight and less proportion of short chains of amylopectin than those of the untreated sample. X-ray diffraction demonstrated that the relative crystallinity of starch in noodles was increased by HMT and RT treatments while it was decreased by MW and SF treatments compared to untreated noodles. Fourier transform infrared (FTIR) analysis revealed that the short-range ordered degree and intra-molecular hydrogen bond intensity were both enhanced by thermal treatments. A tighter and smoother microstructure with fewer pores and cracks in the treated noodles was observed by scanning electron microscopy (SEM). These structural changes could provide a better understanding of the lower starch digestion rate.

Effects of tempering with steam on the water distribution of wheat grains and quality properties of wheat flour.

In this study, the effects of tempering with steam on the water distribution of wheat grains and the microbial load in wheat flour were investigated, as well as the physicochemical properties of wheat flour. Results showed that when steam treatment time was 320 s, the total plate count (TPC), yeast and mold count (YMC), and mesophilic aerobic spores (MAS) in flour decreased by 1.74, 1.99 and 1.01 lgCFU/g, respectively. Nuclear magnetic resonance (NMR) results showed that tempering with steam accelerated the water distribution of grains and significantly (p < 0.05) shortened the tempering time. Moreover, flour yield, particle size, ash content, and damaged starch content of flour were all altered. Furthermore, after tempering with steam, proteins were aggregated and starches were partially gelatinized, which caused dough development time and stability of flour increasing. Collectively, our findings indicated steam tempering could shorten the tempering time and improve the qualities of flour partly.

Revealing the effect mechanism of NaCl on the rheological properties of dough of Chinese traditional hand-stretched dried noodles.

Chinese traditional hand-stretched dried noodle is very popular in China for its unique taste and flavor quality, and NaCl plays a vital role in its processing. The effects of NaCl (1%-6%, w/w) on rheological and gluten properties of dough of Chinese traditional hand-stretched dried noodle were studied. The addition of NaCl (1%-4% w/w) enhanced storage modulus, loss modulus and extensibility of dough, while these rheological parameters started to decreased when NaCl amount reached 5% (w/w). With salt addition increased from 0% to 6% (w/w), the solubility of gluten in SDS medium showed a significant (p < 0.05) decreasing trend, while opposite result was found on the yield and G' of gluten macro polymer. These changes on gluten indicated that the interaction among gluten molecules increased with the increase of salt amount. Excessive salt (5%-6%, w/w) disrupted the gluten network, which was responsible for the reduction of dynamic and extensional properties.