Abstract
BACKGROUND: γ-Aminobutyric acid (GABA) is a non-protein amino acid with several functions in the human body. Although freeze-thawing could effectively accumulate GABA in soybean sprouts, the mechanism has not been revealed. The mechanism by which freeze-thawing enhances GABA accumulation in germinated soybean was revealed by evaluating GABA content, the activity of related synthesis enzymes, and the microstructure of the tissues and cells of sprouts. The germinated soybeans were treated at different temperatures (from -196 °C to 25 °C) for 12 h and then thawed at 25 °C for 6 h. RESULTS: The results showed that GABA content in frozen soybean sprouts did not change significantly before thawing. After thawing, the GABA content of sprouts increased by 83.9% and 82.9% when treated by liquid nitrogen flash freeze at - 80 °C for 12 h compared with the control (4 °C treatment for 12 h). The results indicated that GABA formation mainly occurred during thawing. However, glutamate decarboxylase (GAD), diamine oxidase (DAO), and aminoaldehyde dehydrogenase (AMADH) activity decreased during thawing. Based on the malonaldehyde (MDA) content and microstructure of sprouts, it was suggested that freezing at lower temperatures (< -20 °C) maintained the integrity of the cell structure, while the tissues and cell membranes were broken during thawing. CONCLUSION: These results could provide evidence for the hypothesis that GABA formation resulted from full contact between enzymes and substrates during thawing, rather than the contribution of higher enzyme activity. © 2019 Society of Chemical Industry.
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Claims 8
Claim · model-written summary
GABA content did not significantly change before thawing.
- Taxon
- soybean
Glycine maxe0 - Organ / stage
- sproutse0
- Outcome
- GABA contente0
- Direction
- did not changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GABA content in frozen soybean sprouts did not change significantly before thawing”
Claim · model-written summary
After thawing, liquid nitrogen flash freezing increased sprout GABA by 83.9% relative to the 4 °C control.
- Taxon
- soybeanGlycine maxt0
- Treatment
- liquid nitrogen flash freezee0
- Outcome
- GABA contente0
- Direction
- increasede0
- Value
- 83.9%e0
- Comparator
- control (4 °C treatment for 12 h)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After thawing, the GABA content of sprouts increased by 83.9% and 82.9% when treated by liquid nitrogen flash freeze at - 80 °C for 12 h compared with the control (4 °C treatment for 12 h)”
t0“germinated soybean”
Claim · model-written summary
After thawing, freezing at - 80 °C increased sprout GABA by 82.9% relative to the 4 °C control.
- Taxon
- soybeanGlycine maxt0
- Treatment
- - 80 °C for 12 he0
- Outcome
- GABA contente0
- Direction
- increasede0
- Value
- 82.9%e0
- Comparator
- control (4 °C treatment for 12 h)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After thawing, the GABA content of sprouts increased by 83.9% and 82.9% when treated by liquid nitrogen flash freeze at - 80 °C for 12 h compared with the control (4 °C treatment for 12 h)”
t0“germinated soybean”
Claim · model-written summary
GABA formed mainly during thawing.
- Taxon
- soybeanGlycine maxt0
- Outcome
- GABA formatione0
- Qualifier
- during thawinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GABA formation mainly occurred during thawing”
t0“germinated soybean”
Claim · model-written summary
GAD, DAO and AMADH activity declined during thawing.
- Taxon
- soybeanGlycine maxt0
- Gene
- glutamate decarboxylase (GAD), diamine oxidase (DAO), and aminoaldehyde dehydrogenase (AMADH)e0
- Outcome
- activitye0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“glutamate decarboxylase (GAD), diamine oxidase (DAO), and aminoaldehyde dehydrogenase (AMADH) activity decreased during thawing”
t0“germinated soybean”
Claim · model-written summary
Freezing below -20 °C appeared to preserve cellular integrity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- freezing at lower temperatures (< -20 °C)e0
- Outcome
- integrity of the cell structuree0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“freezing at lower temperatures (< -20 °C) maintained the integrity of the cell structure”
t0“germinated soybean”
Claim · model-written summary
Sprout tissues and cell membranes broke during thawing.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- tissues and cell membranese0
- Outcome
- tissues and cell membranes were brokene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the tissues and cell membranes were broken during thawing”
t0“germinated soybean”
Claim · model-written summary
Authors hypothesized that enzyme substrate contact during thawing caused GABA formation.
- Taxon
- soybeanGlycine maxt0
- Outcome
- GABA formatione0
- Qualifier
- full contact between enzymes and substrates during thawinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GABA formation resulted from full contact between enzymes and substrates during thawing”
t0“germinated soybean”
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