Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Oct 20;12(20):3848.
doi: 10.3390/foods12203848.

Nutritional Content and Microbial Load of Fresh Liang, Gnetum gnemon var. tenerum Leaves

Sunisa Siripongvutikorn  1 , Worapong Usawakesmanee  1 , Supachai Pisuchpen  2 , Nicha Khatcharin  1 , Chanonkarn Rujirapong  1
Affiliations

Nutritional Content and Microbial Load of Fresh Liang, Gnetum gnemon var. tenerum Leaves

Sunisa Siripongvutikorn et al. Foods. .

Abstract

Liang (Gnetum gnemon var. tenerum) leaves are widely consumed as a green vegetable in Southern Thailand, and the plant is valued for its nutritional benefits. However, like other leafy greens, liang is vulnerable to microbial contamination, generating foodborne illnesses. This study examined the nutritional content and microbial load of liang leaves at different maturity stages and the effects of washing with chlorinated water. Various growth stages were analysed for proximate composition, amino acids, vitamins, and minerals. Results revealed distinct nutritional profiles, with tip leaves rich in protein and fat and intermediate leaves high in dietary fibre. Liang leaves are abundant in essential amino acids and proteins. Washing with chlorinated water increased leaf weight due to water retention but also caused physical damage, fostering microbial growth and spoilage. Microbiological analysis showed marginal reductions in total viable counts after washing with chlorinated water and significant decreases in coliform and Escherichia coli counts. However, stem detachment during washing increased the coliform and E. coli counts. Liang leaves exhibited favourable nutritional content, especially in the intermediate stage. Proper handling and storage of liang leaves are crucial to preventing physical damage and microbial contamination. Improved food safety measures, including appropriate post-harvest washing and handling of leafy vegetables, will ensure that consumers can safely enjoy the nutritional benefits of liang leaves.

Keywords: Gnetum gnemon; nutritional; preparation; quality; stem; washing.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Intercropping of liang shrubs with water irrigation pipe system (a) Drilled well for the farm (b).
Figure 2
Figure 2
Tip, young and intermediate (pae-salat) stages of liang leaves and stems: T means tip; Y means young; I means intermediate; S means stem.
Figure 3
Figure 3
Weight gain of liang (Gnetum gnemon var. tenerum) leaves after storage at 4 °C for 8 days. NWS means no-washing with stem; NWNS means no-washing without stem; WS means washing with stem; WNS means washing without stem.
Figure 4
Figure 4
Liang leaves from the field (baseline or initial quality) (a); liang leaves after 20 days storage at 4 °C; no-washing with stem (NWS) (b); no-washing without stem (NWNS) (c); washing with stem (WS) (d); washing without stem (WNS) (e).
Figure 5
Figure 5
Damage level of liang (Gnetum gnemon var. tenerum) leaves after storage at 4 °C for 8 days. NWS means no-washing with stem; NWNS means no-washing without stem; WS means washing with stem; WNS means washing without stem.
Figure 6
Figure 6
Total viable count of liang (Gnetum gnemon var. tenerum) leaves after storage at 4 °C for 12 days. Different uppercase letters (A–D) indicate significant differences within the same treatment group. Different lowercase letters (a–c) indicate significant differences between treatment groups within each day (p < 0.05). NWS means no-washing with stem; NWNS means no-washing without stem; WS means washing with stem; WNS means washing without stem.
Figure 7
Figure 7
Yeast and mould of liang (Gnetum gnemon var. tenerum) leaves after storage for 12 days. Different uppercase letters (A–D) indicate significant differences within the same treatment group. Different lowercase (a–c) letters indicate significant differences between treatment groups within each day (p < 0.05). NWS means no-washing with stem; NWNS means no-washing without stem; WS means washing with stem; WNS means washing without stem.
See this image and copyright information in PMC

References

    1. Anisong N., Siripongvutikorn S., Wichienchot S., Puttarak P. A comprehensive review on nutritional contents and functional properties of Gnetum gnemon Linn. Food Sci. Technol. 2022;42:e100121. doi: 10.1590/fst.100121. - DOI
    1. Suksanga A., Siripongvutikorn S., Yupanqui T.C., Leelawattana R. The potential antidiabetic properties of Liang (Gnetum gnemon var. tenerum) leaves. Food Sci. Technol. 2022;42:e64522. doi: 10.1590/fst.64522. - DOI
    1. Rosberg A.K., Darlison J., Mogren L., Alsanius B.W. Commercial wash of leafy vegetables do not significantly decrease bacterial load but leads to shifts in bacterial species composition. Food Microbiol. 2021;94:103667. doi: 10.1016/j.fm.2020.103667. - DOI - PubMed
    1. Mogren L., Windstam S., Boqvist S., Vagsholm I., Soderqvist K., Rosberg A.K., Linden J., Mulaosmanovic E., Karlsson M., Uhlig E., et al. The hurdle approach—A holistic concept for controlling food safety risks associated with pathogenic bacterial contamination of leafy green vegetables: A review. Front. Microbiol. 2018;9:1965. doi: 10.3389/fmicb.2018.01965. - DOI - PMC - PubMed
    1. López-Gálvez F., Allende A., Gil M.I. Recent progress on the management of the industrial washing of fresh produce with a focus on microbiological risks. Curr. Opin. Food Sci. 2021;38:46–51. doi: 10.1016/j.cofs.2020.10.026. - DOI

LinkOut - more resources