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The combination effect of microwave (MW) irradiation, ε‐poly‐L‐lysine (ε‐pL), and calcium propionate (CP) on the shelf life and quality of Qingke barley fresh noodles (QBFN) stored at 4 ± 1°C were investigated in terms of total plate count (TPC), bacterial diversity, water characteristics, and noodle qualities. The results showed that the initial TPC of the control and MW + ε‐pL + CP groups were 4.40 log cfu/g and 3.75 log cfu/g, respectively. The combination of MW, ε‐pL and CP effectively inhibited the growth of microorganisms, and the shelf life of the MW + ε‐pL + CP group extended from 6 days (control) to 12 days. Compared with the control, the MW + ε‐pL + CP group maintained the better noodle quality, color, cooking quality, and relatively higher abundance of strong bound and weakly bound water during the storage. Practical applications: This study may provide a basis data for further study about the changes of bioactive compounds, antioxidant activities, digestible properties, and volatile compounds in Qingke barley fresh noodles QBFN stored at law temperature, as well as offer data for manufacturers to promote its industrialization. [ABSTRACT FROM AUTHOR]

Summary: Microbial diversity and volatile compounds in Qingke barley fresh noodles (QBFN) with different storage time at 25 ± 1 °C were investigated. The results showed that Pseudomonas, Pantoea, Erwinia and Alternaria, Pyrenophora, Penicillium were the dominant microorganisms in edible QBFN (stored for 0 and 12 h), while Pantoea, Erwinia, Bacillus and Penicillium, Aspergillus were the dominant spoilage microorganisms in deteriorated QBFN (stored for 18 h). The edible QBFN have high concentration of aldehydes (61.27 μg kg−1), furan and pyrazines (60.87 μg kg−1), alcohols (49.74 μg kg−1) and ketones (29.74 μg kg−1) that give basic flavours to the QBFN. As storage time increased, the concentrations of above volatile compounds decreased, and new esters and sulphuric compounds which gave unpleasant odours to the QBFN appeared. Multivariate data analysis methods showed that 2‐pentyl‐furan, hexanal, 5‐Ethylcyclopent‐1‐enecarboxaldehy, cyclohexanol and methyl allyl sulphide, ethyl isovalerate were the main volatile compounds that make a difference in flavour between the edible and deteriorated QBFN. [ABSTRACT FROM AUTHOR]

Summary: The impact of noodle processing, storage and cooking on the total phenol content (TPC) and total flavonoid content (TFC) was assessed. Total phenol content (TPC) and total flavonoid content (TFC) of mixed flour were 77.50 and 39.56 mg per 100 g, respectively, and it decreased to 71.80 and 36.30 mg per 100 g after noodle processing. For the fresh Qingke barley noodles (FQBNs), stored at 25 °C, both TPC and TFC decreased significantly during storage. After cooking the fresh noodles, the TPC of the noodles stored for 0 and 4 h increased, while it decreased for the noodles stored for 8, 16 and 24 h; the TFC of all cooked Qingke barley noodles (CQBNs) decreased. Compared with the flour, the DPPH•, ABTS•+, HO• and O2∙- scavenging ability and ferric reducing antioxidant power (FRAP) decreased significantly (P < 0.05) after noodle processing. For FQBN, increased storage time led to a reduction in antioxidant ability. After cooking, the DPPH• and HO• scavenging ability and FRAP of noodles stored at 25 °C for 0 and 4 h, and the ABTS•+ and O2∙- scavenging ability of noodles stored at 25 °C for 0, 4 and 8 h increased. Overall, noodle processing, storage and cooking will affect the phenolic compound content and antioxidant activities of barley noodles. Although the shelf life of FQBN is 17 h at 25 °C, from the perspective of nutrition, it is not suitable for long‐term storage, and it is best choice to consume it within the first 4 h. [ABSTRACT FROM AUTHOR]

In this work, the effect of microwave (MW), ε‐poly‐L‐lysine (ε‐PL), calcium propionate (CP), and their combinations on the shelf life and quality characteristics of highland barley fresh noodle (HBFN) was studied. Firstly, the mixed flour was treated by MW (800 W) for different time. Subsequently, HBFN was prepared by mixing flour and sterilized water with addition of 0.04% ε‐PL combined with different concentrations of CP (0.025%, 0.020%, 0.015%) and stored at 25 ± 1°C. Changes of total plate count (TPC), moisture content, water state, textural properties, color, and pH in HBFN were monitored during storage. The results indicated that microwave treatment (40 s) provided 30% reduction of initial TPC of the flour without decline of noodle quality. Shelf life of HBFN treated with MW + ε‐PL (0.04%) + CP (0.02%/0.025%) reached 80 and 88 hr, respectively, and had good edible qualities during storage. [ABSTRACT FROM AUTHOR]

Changes of microbes, bioactive compounds, protein structures, and noodle qualities in Qingke barley (one of the Tibetan barleys) fresh noodles (QBFN) stored at 25°C were evaluated. The results showed that an increase in total plate count (TPC) and total mold count (TMC) occurred after 12 hr, and Pantoea, Erwinia, Bacillus for the bacteria, Penicillium and Aspergillus for the mold became dominant spoilage microorganisms at the end of storage.In addition, according to the microbial growth at 25°C, the microbial growth models were built for both TPC and TMC, and the microbial growth models were well fitted by logistic model, with higher fitting precision. The fitting equations were Y = 3.7642–3.7/[1+(t/26.597)3.1], R2 = 0.9942 and Y = 1.7553–1.7546/[1+(t/19.8)3.4], R2 = 0.9999. Due to the polyphenol oxidization (PPO), the total phenol and flavonoid contents decreased from 77 and 36 mg/100 g to 49 and 18 mg/100 g, respectively. The pH value, color, textural properties, and cooking quality decreased significantly (p < .05). The disulfide (SS) bond content decreased from 2.9 to 1.6 µmol/g, while the free sulfydryl (SH) content increased from 0.9 to 1.3 µmol/g; the cost of a significant reduction in α‐helix induced an increase in the random coil with the deterioration of QBFN. The relative abundance of strong bounded water decreased while the relative abundance of weakly bounded water and free water increased, which indicated the destruction of the structure of protein encapsulating starch in QBFN. Moreover, Pearson correlation analysis showed that changes of TPC, TMC, SS/SH bond content, and water state were also significantly correlated with the appearance, textural properties, and cooking quality of QBFN. Practical applications: Investigating changes in microbe diversity, bioactive compound, protein structure, water state, and noodle quality during storage at 25 ± 1°C will help us understand the mechanisms and dynamics of QBFN deterioration. Identification of the dominant microbes that contribute to noodle spoilage and the changes of bioactive compounds help us determine suitable methods to inhibit the growth of microbes and to prevent the loss of bioactive compounds. Moreover, correlation analysis may help us understand the relationship between noodle quality and microbe, water state, and protein structure, and provide a theoretical basis for improving noodle quality. [ABSTRACT FROM AUTHOR]