Haijie Liu

Dual effects of slightly acidic electrolyzed water (SAEW) treatment on the accumulation of γ-aminobutyric acid (GABA) and rutin in germinated buckwheat.

In the present study, the dual effects of slightly acidic electrolyzed water (SAEW) treatment on γ-aminobutyric acid (GABA) and rutin accumulation of germinated buckwheat were evaluated during germination. The results showed that SAEW treatment (pH 5.83, ACC of 20.3 mg/L) could promote the accumulation of GABA and rutin in germinated buckwheat. The GABA and rutin contents of SAEW-germinated buckwheat reached 143.20 and 739.9 mg/100 g respectively, which is significantly higher than those of control (P<0.05). Moreover, SAEW treatment could increase the activity of glutamic acid decarboxylase (GAD) and phenylalanine ammonialyase (PAL) and thus result in the GABA and rutin accumulation of germinated buckwheat. The results suggested that SAEW treatment could promote the rutin accumulation of germinated buckwheat by influencing phenylpropanoid secondary metabolic pathway instead of the inhibition of rutin degrading enzyme (RDE) activity. In addition, SAEW treatment had no adverse impact on the sprouts growth and could reduce the microbial populations of germinated buckwheat during germination.

Effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in germinated brown millet

The accumulation of γ-aminobutyric acid and the microbial decontamination are concerned increasingly in the production of sprouts. In this work, the effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in the germinated brown millet was evaluated by high performance liquid chromatography during germination. The results showed that slightly acidic electrolyzed water with appropriate available chlorine (15 or 30 mg/L) could promote the accumulation of γ-aminobutyric acid by up to 21% (P < 0.05). However, the treatment with slightly acidic electrolyzed water could not enhance the sprouts growth of the germinated brown millet. The catalase and peroxidase activities of the germinated brown millet during germination were in agreement with the sprouts growth. Our results suggested that the accumulation of γ-aminobutyric acid was independent of the length of sprouts in germinated grains. Moreover, the treatment with slightly acidic electrolyzed water significantly reduced the microbial counts in the germinated millet (P < 0.05) and the treatment with high available chlorine concentration (15 and 30 mg/L) showed stronger anti-infection potential in the germinated brown millet than that of lower available chlorine concentration (5 mg/L). In conclusion, the treatment with slightly acidic electrolyzed water is an available approach to improve the accumulation of γ-aminobutyric acid and anti-infection potential in the germinated brown millet, and it can avoid too long millet sprouts.

Physicochemical changes in myofibrillar proteins extracted from pork tenderloin thawed by a high-voltage electrostatic field

The application of a high-voltage electrostatic field (HVEF) is a novel method for thawing. To determine the effects of HVEF thawing (voltage range: -25kV to 0kV) on myofibrillar protein oxidation and/or denaturation and to provide a theoretical understanding of this process, pork tenderloin was thawed by traditional and HVEF methods. Based on the total sulfhydryl and carbonyl contents, further protein oxidation did not occur during HVEF thawing. It was proposed that the free radical-mediated oxidation of myofibrillar proteins was hindered by HVEF. The results of dynamic rheological analysis, protein aggregation and gel texture studies showed that HVEF thawing, especially -10kV HVEF thawing, led to better indicators than those achieved under air thawing. A higher abundance of proteins extracted from -10kV HVEF-thawed samples compared with air-thawed samples was found. Finally, this study showed that thawing under -10kV conditions did not affect the structure of myofibrillar proteins.

Differences of Bactericidal Efficacy on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis of Slightly and Strongly Acidic Electrolyzed Water

In the present study, the disinfection efficacy of slightly acidic electrolyzed water (SAEW) and strongly acidic electrolyzed water (AEW) was tested on three bacteria, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis and the disinfection mechanism was discussed. The results showed that SAEW had a stronger antibacterial efficacy against these tested bacteria in comparison with AEW. The results also showed that both SAEW and AEW treatments could damage the cell membrane, which was demonstrated microcosmically by scanning electron microscopy (SEM), thus causing leakages of protein, DNA, RNA, and ATP, resulting in the death of microbes. Moreover, AEW treatment could not cause the degradations of DNA and RNA, and nucleic acids including DNA and RNA are not the target point of its bactericidal efficacy. However, SAEW could maybe cause the degradation of RNA, and RNA may be the target in its antibacterial activity. We suggested that the differences in antibacterial efficacy between SAEW and AEW could be explained by the different impacts on RNA of tested strains.

The relationship between antioxidant enzymes activity and mungbean sprouts growth during the germination of mungbean seeds treated by electrolyzed water

Abstract Slightly acidic electrolyzed water (SAEW) could promote the germination and growth of mungbean sprouts, and electron spin resonance analyses of SAEW showed that besides available chlorine, reactive oxygen species (ROS) existed in SAEW. Further research showed that, a series of antioxidant enzymes activity were also affected by SAEW. Lower superoxide dismutase activity and higher peroxidase, catalase and ascorbate peroxidase activity led to less hydrogen peroxide accumulated in mungbean sprouts treated by SAEW. Thus, the available chlorine and ROS present in the SAEW played a role in the mungbean sprouts’ antioxidant mechanism, which in turn appeared as a growth-promoting effect on the mungbean sprouts.

Effect of slightly acidic electrolyzed water on bioactive compounds and morphology of broccoli sprouts

The producers of broccoli sprouts have become increasingly interested in improving their sulforaphane content. This study has evaluated the effects of slightly acidic electrolyzed water (SAEW) with different available chlorine concentrations (ACC) on broccoli sprouts: their content of some bioactive compounds such as glucosinolates, their morphology, and their total bacterial counts. The results have shown that SAEW might affect the content of sulforaphane by influencing the content of glucosinolates and the activity of myrosinase. SAEW inhibited the growth of broccoli sprouts: their fresh weight decreased as the available chlorine concentration (ACC) of the SAEW increased, but the different solutions did not affect their dry weight. The number of microorganisms on the broccoli sprout decreased by 1.71logCFU/g after using the SAEW with ACC value of 50mg/L treatment compared with tap water treatment. Overall, although SAEW adversely affected the morphology of broccoli sprouts, with a suitable ACC it can be a useful tool for enhancing the amount of secondary metabolites and reducing the microbial counts on broccoli sprouts intended for fresh consumption as a functional food.

Biochemical characterization of a novel xylanase from Paenibacillus barengoltzii and its application in xylooligosaccharides production from corncobs

A novel xylanase gene (PbXyn10A) from Paenibacillus barengoltzii was cloned and expressed in Escherichia coli. PbXyn10A had an open reading frame of 3,063 bp, and its deduced amino acid sequence shared the highest identity of 72% with a xylanase from Paenibacillus curdlanolyticus. The recombinant xylanase (PbXyn10A) was purified and biochemically characterized. PbXyn10A was most active at pH 6.5 and 60 °C, respectively. It exhibited strict substrate specificity towards birchwood xylan, beechwood xylan and oat-spelt xylan, with Km values of 2.19, 2.04 and 2.51 mg/mL, respectively. The enzyme hydrolyzed xylan to yield mainly xylooligosaccharides (XOS) with degree of polymerization 2-4. A new strategy for XOS production from corncobs pretreated by steam explosion using acidic electrolyzed water, followed by enzymatic hydrolysis was developed. The highest XOS yield of 75% (based on xylan in raw corncobs) was achieved. This is the first report on a xylanase from Paenibacillus barengoltzii.

Effect of electrolyzed oxidizing water treatment on the reduction of nitrite levels in fresh spinach during storage.

Leafy vegetables are the major source of nitrite intake in the human diet, and technological processing to control nitrite levels in harvested vegetables is necessary. In the current work, the effect of electrolyzed oxidizing water (EOW) on the nitrite and nitrate levels in fresh spinach during storage was studied. EOW treatment, including slightly acidic electrolyzed water and acidic electrolyzed water, was found to effectively reduce nitrite levels in fresh spinach during storage; levels in the late period were 30 to 40% lower than that of the control. However, the nitrate levels in fresh spinach during storage were not influenced by EOW treatment. The reduction of nitrite levels in EOW-treated fresh spinach during storage can be attributed to the inactivation of nitrate reductase directly and to the reduction of bacterial populations. Our results suggest that treatment with slightly acidic electrolyzed water may be a better choice to control nitrite levels in fresh vegetables during storage. This study provided a useful method to reduce nitrite levels in fresh spinach.