Our lab’s Research on Sprouts, Microgreens, and Germination

Our lab's research has systematically investigated the biochemical transformations that occur during the germination of various edible seeds, establishing sprouts and microgreens as valuable sources of functional and nutritional ingredients. The work spans broad comparative analyses, in-depth metabolomic profiling, and the study of specific bioactive components.

1.     Enhancement of Phytochemicals and Antioxidant Capacity

A foundational theme of our research is demonstrating that germination is a highly effective method for enhancing the nutritional profile of edible seeds. We have consistently found that the process significantly increases total phenolic content (TPC), total flavonoid content (TFC), and overall antioxidant capacity across a wide variety of species. This was comprehensively shown in a comparative study of 17 different edible seeds, where germination boosted these properties in most species, with white radish sprouts emerging as a particularly potent source of antioxidants (Liu et al., 2022).

Our investigations have explored this phenomenon in specific cultivars, including peanuts (Yang et al., 2019), mung beans (Gan et al., 2016), and black wheat (Gan et al., 2017). A key finding from this work is the strong positive correlation between increased phenolic content and antioxidant activity, indicating that phenolic compounds are the primary contributors to the enhanced bioactivity of sprouts (Gan, Lui, Wang, et al., 2016; Yang et al., 2019). Furthermore, our work has uniquely considered both solvent-soluble and insoluble (bound) phenolics, revealing that bound fractions also contribute substantially to the total antioxidant profile and are significantly enhanced by germination (Gan, Chan, et al., 2016; Gan, Sui, et al., 2017). This body of work has been consolidated in review articles and a book chapter, where we position germination as a simple and "green" food engineering technique to accumulate natural bioactive compounds for promoting health and preventing chronic diseases (Gan et al., 2017; Gan, Sui, et al., 2019).

2.     In-depth Metabolomic and Flavor Profiling

Moving beyond general antioxidant measurements, our lab has employed advanced analytical techniques to create detailed metabolite profiles of sprouts. Using widely targeted metabolomics, we identified over 1000 metabolites in three broccoli cultivars, pinpointing hundreds of compounds that were significantly altered during germination. This analysis revealed that key metabolic pathways, such as linoleic acid metabolism, were consistently activated, providing a deeper understanding of the biochemical shifts that enhance nutritional value (Li et al., 2023). A similar phenolic-focused metabolomic analysis of white radish sprouts identified 198 significantly altered phenolic metabolites, with major accumulations in beneficial phenolic acids and flavonoids, confirming that biosynthesis pathways like the phenylpropanoid pathway are highly active during germination (Liu et al., 2022).

Complementing this, we have also characterized the flavor profiles of sprouts. A comprehensive study on broccoli sprouts using HS-SPME-GC/MS identified 364 volatile and flavor components. We found that germination generally enhanced taste intensity, particularly for umami and sweet tastes, which was linked to an increase in specific amino acids and sugars. This work provides critical insights into consumer acceptance by connecting biochemical changes directly to sensory attributes (Xia et al., 2024).

3.     Structural and Functional Analysis of Specific Components

Our research also delves into the structural characteristics and functional properties of specific macromolecules in microgreens. A recent study focused on soluble dietary fibers from various quinoa microgreens, identifying them as complex pectic-polysaccharides. We characterized their molecular weights and structural domains and demonstrated their potent in vitro antioxidant, antiglycation, prebiotic, and immunoregulatory effects. This work helps establish the functional role of specific components beyond phenolics and provides a basis for developing value-added healthy products from microgreens (Wu et al., 2024).

Additionally, we have examined how post-harvest processing affects the bioactive compounds in sprouts. An investigation into hot air drying of mung bean sprouts showed that while drying at high temperatures induced browning, it also unexpectedly increased TPC and antioxidant capacity compared to freeze-drying. This study highlighted the complex interactions between processing, browning pigments, and phenolic profiles, offering practical applications for creating shelf-stable, functional food ingredients (Gan et al., 2017).

4.     Significance and Novelty of Our Work

The collective body of our lab's work is significant for its comprehensive and multi-faceted approach to understanding the value of sprouts and microgreens. The novelty of our research lies in several key areas:

(1) Breadth and Depth: We have moved from broad screenings of numerous species to deep, metabolome-level investigations of specific, high-value cultivars like broccoli and white radish. This provides both a wide-angle view of germination's benefits and a high-resolution map of the underlying biochemical changes.

(2) Holistic Analysis: Our lab uniquely considers not only soluble phytochemicals but also the often-overlooked insoluble-bound fractions, revealing a more complete picture of the antioxidant potential of sprouts.

(3) Bridging Biochemistry and Consumer Experience: By linking detailed metabolomic data with flavor profiling, our research bridges the gap between fundamental biochemistry and practical consumer acceptance, which is a novel and crucial aspect for promoting the consumption of these healthy foods.

(4) Focus on Specific Functional Components: The structural and bioactivity analysis of components like soluble dietary fibers in quinoa microgreens moves the field beyond a general focus on phenolics and explores other key functional ingredients, opening new avenues for product development.

In summary, our research provides robust scientific evidence supporting the cultivation and consumption of sprouts and microgreens. It not only confirms their enhanced nutritional and functional properties but also provides detailed, mechanism-based insights that are valuable for cultivar selection, product development, and the promotion of these foods for human health.

Acknowledgement

We would like to thank the hard work and collaboration of all my team members and collaborators involved in this work.

Our Publication List

Gan, R. Y., Chan, C. L., Yang, Q. Q., Li, H. B., Zhang, D., Ge, Y. Y., Gunaratne, A., Ge, J., & Corke, H. (2019). Bioactive compounds and beneficial functions of sprouted grains. In Sprouted Grains: Nutritional Values, Production, and Applications (Chapter 9, pp. 191-246). Elsevier Inc. and AACC International. https://doi.org/10.1016/B978-0-12-811525-1.00009-9

Gan, R. Y., Lui, W. Y., Chan, C. L., & Corke, H. (2017). Hot Air Drying Induces Browning and Enhances Phenolic Content and Antioxidant Capacity in Mung Bean (Vigna radiata L.) Sprouts. Journal of Food Processing and Preservation, 41(1), e12846. http://dx.doi.org/10.1111/jfpp.12846

Gan, R. Y., Lui, W. Y., Wang, M. F., Sui, Z. Q., & Corke, H. (2016). Accumulation of solvent-soluble and solvent-insoluble antioxidant phenolics in edible bean sprouts: implication of germination. Functional Foods in Health and Disease, 6(8), 519-535.

Gan, R. Y., Lui, W. Y., Wu, K., Chan, C. L., Dai, S. H., Sui, Z. Q., & Corke, H. (2017). Bioactive compounds and bioactivities of germinated edible seeds and sprouts: An updated review. Trends in Food Science & Technology, 59, 1-14. http://dx.doi.org/10.1016/j.tifs.2016.11.010

Gan, R. Y., Sui, Z. Q., Yang, Q. Q., & Corke, H. (2017). Enhancement of antioxidant capacity and phenolic content in soluble and bound extracts of germinated black wheat. Journal of Shanghai Jiao Tong University (Agricultural Science), 35(3), 1-9,16.

Gan, R. Y., Wang, M. F., Lui, W. Y., Wu, K., & Corke, H. (2016). Dynamic changes in phytochemical composition and antioxidant capacity in green and black mung bean (Vigna radiata) sprouts. International Journal of Food Science and Technology, 51(9), 2090-2098. http://dx.doi.org/10.1111/ijfs.13185

Li, M. Y., Liu, Y., Kong, K. W., Geng, F., Liu, H. Y., & Gan, R. Y. (2023). Widely targeted metabolomic analysis and antioxidant properties of seeds and sprouts from different broccoli cultivars. LWT-Food Science and Technology, 182, 114859. http://dx.doi.org/10.1016/j.lwt.2023.114859

Liu, H. Y., Liu, Y., Li, M. Y., Ge, Y. Y., Geng, F., He, X. Q., Xia, Y., Guo, B. L., & Gan, R. Y. (2022). Antioxidant capacity, phytochemical profiles, and phenolic metabolomics of selected edible seeds and their sprouts. Frontiers in Nutrition, 9, 1067597. http://dx.doi.org/10.3389/fnut.2022.1067597

Wu, D. T., Li, J., Wang, J., Lei, J., Gan, R. Y., Qin, P. Y., Hu, Y. C., Wu, X. Y., & Zou, L. (2024). Comparison of soluble dietary fibers from various quinoa microgreens: Structural characteristics and bioactive properties. Food Research International, 181, 114108. http://dx.doi.org/10.1016/j.foodres.2024.114108

Xia, Y., Li, M. Y., Wadood, S. A., Hong, H. J., Liu, Y., Luo, Y. X., Wang, Y. Y., Liu, H. Y., & Gan, R. Y. (2024). Identification of volatile and flavor metabolites in three varieties of broccoli sprouts. Food Chemistry-X, 24, 101862. http://dx.doi.org/10.1016/j.fochx.2024.101862

Yang, Q. Q., Cheng, L., Long, Z. Y., Li, H. B., Gunaratne, A., Gan, R. Y., & Corke, H. (2019). Comparison of the Phenolic Profiles of Soaked and Germinated Peanut Cultivars via UPLC-QTOF-MS. Antioxidants, 8(2), 47. http://dx.doi.org/10.3390/antiox8020047