Postharvest production and enhancement of resveratrol and piceatannol in sugarcane
Inventors
Boue, Stephen M. • Burow, Matthew E. • Bhatnagar, Deepak
Assignees
Tulane University • US Department of Agriculture USDA
Publication Number
US-9227898-B2
Publication Date
2016-01-05
Expiration Date
2033-01-28
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Abstract
It has been discovered that irradiating the cut side of sugarcane billets, preferably 2-50 mm, with UVB or UVC light or combinations thereof initiates stilbene production, particularly resveratrol and piceatannol. In an embodiment the cut sides of sugarcane billets of a predetermined thickness are irradiated with Ultraviolet-C or Ultraviolet-B light or combinations thereof at an intensity and for a duration of time sufficient to produce a significant increase in a level of one or more stilbenes in the irradiated billets compared to a level of stilbenes in billets that are not irradiated; and the irradiated sugarcane billets are maintained for at least about three days up to about 20 days, to optimize stilbene levels.
Core Innovation
It has been discovered that irradiating the cut side of sugarcane billets with Ultraviolet-C (UVC) or Ultraviolet-B (UVB) light or combinations thereof initiates the production of stilbenes, particularly resveratrol and piceatannol, which are phenolic compounds with beneficial biological properties. This irradiation is performed on sugarcane billets of a predetermined thickness, typically ranging from 2 mm to 50 mm, and is carried out at an intensity and duration sufficient to produce a significant increase in stilbene levels compared to non-irradiated billets. After irradiation, the billets are maintained for a period ranging from about three days up to about 20 days to optimize stilbene production.
The problem being solved addresses the lack of significant natural sources of resveratrol and piceatannol, especially in sugarcane, which under normal conditions does not contain these stilbenes. Given the health-promoting benefits of stilbenes, including antibacterial, antifungal, cardioprotective, anti-inflammatory, neuroprotective, and anticancer actions, there is a need for methods to produce and enhance these compounds in plants. Prior to this invention, piceatannol was found only in sugarcane infected by fungus but not in healthy or wounded plants, and resveratrol had not been detected in sugarcane.
This invention provides a novel postharvest method that induces and enhances the biosynthesis of stilbenes in sugarcane billets through UV irradiation, which serves as an abiotic stress stimulus. The method includes selecting the optimal billet thickness, UV light intensity (UVB ranging from about 10 mW/cm2 to about 50 W/cm2 and UVC ranging from about 1 mW/cm2 to about 25 mW/cm2), and irradiation duration (10 minutes to 3 hours), followed by controlled incubation in conditions that prevent stilbene isomerization. Additionally, stilbene production can be enhanced by inoculating sugarcane with fungi that increase stilbene synthesis, such as Collectotrichum falcatum or Aspergillus sojae.
Claims Coverage
The patent includes two independent methods and product claims covering UV irradiation of sugarcane billets and leaves to increase stilbene levels and subsequent maintenance for stilbene optimization. The main inventive features focus on the process conditions, resulting stilbene enrichment, and embodiments with fungal inoculation and specific sugarcane varieties.
UV irradiation of sugarcane billets to enhance stilbene production
A method comprising providing sugarcane billets of predetermined thickness (2 to 50 mm); irradiating the cut side with Ultraviolet-C, Ultraviolet-B, or combinations thereof at an intensity and duration sufficient to significantly increase stilbenes compared to non-irradiated billets; maintaining the irradiated billets for about three to twenty days; and selecting the irradiated billets.
Maintenance conditions to avoid stilbene isomerization
Maintaining the irradiated billets at light levels that do not cause stilbene isomerization during the post-irradiation maintenance phase.
Specific parameters for irradiation and temperature control
Using UVB light intensity ranging from about 10 mW/cm2 to 50 W/cm2, UVC light intensity from about 1 mW/cm2 to 25 mW/cm2, irradiation duration from about 10 minutes to 3 hours; maintaining temperature during irradiation between about 20°C and 40°C, and during subsequent maintenance from about 0°C to 40°C.
Extraction and trans form stilbenes
Optionally extracting one or more stilbenes, typically in the trans form, from the irradiated billets after the maintenance period.
Use of fungal inoculation to enhance stilbene production
Using sugarcane billets obtained from plants inoculated with fungi such as Collectotrichum falcatum or Aspergillus sojae that increase stilbene production in sugarcane.
Irradiation of sugarcane leaves to increase stilbene levels
A method comprising providing sugarcane leaves, irradiating them with Ultraviolet-C or Ultraviolet-B light or combinations thereof to significantly increase stilbenes, maintaining the leaves for at least about three days, and selecting the irradiated leaves.
Sugarcane billets and products enriched with stilbenes
Sugarcane billets made by the described irradiation and maintenance methods, with stilbene content (resveratrol from about 10 μg/g to 500 μg/g and piceatannol from about 100 μg/g to 10,000 μg/g), including specific varieties cv L 97-128, cv HO95, and cv LCP; bagasse and biofuel made from such stilbene-enriched billets.
Non-irradiation stilbene enrichment by maintaining sugarcane billets
A method of providing sugarcane billets between 2 mm and 50 mm thick, maintaining them for about three to twenty days at light levels that prevent stilbene isomerization and temperatures between 0°C and 40°C to produce stilbene-enriched billets without UV irradiation.
These inventive features comprehensively cover methods of postharvest UV irradiation and maintenance to produce and enhance stilbene levels in sugarcane billets and leaves, the use of fungal inoculation to increase stilbenes, specific parameters for irradiation and incubation conditions to prevent isomerization, extraction of stilbenes, and the resulting stilbene-enriched sugarcane products and derivatives such as bagasse and biofuel.
Stated Advantages
High levels of health-promoting stilbenes, specifically resveratrol and piceatannol, can be produced naturally in sugarcane after postharvest UV irradiation and maintenance.
The method allows production of stilbene-enriched sugarcane products without the need for fungal infection or alcohol consumption.
Enhanced stilbene production can be controlled and optimized by varying billet thickness, UV intensity and duration, and incubation conditions, providing flexibility for commercial application.
Maintenance of billets under low light or darkness prevents stilbene isomerization, preserving the desired trans forms for health benefits.
Both the sugarcane juice (sucrose-containing products) and leftover fiber (bagasse) can be enriched with stilbenes, expanding the use of sugarcane by-products for dietary supplements or biofuel.
Documented Applications
Production of stilbene-enriched sugarcane billets and leaves by postharvest UV irradiation and controlled incubation to be used as functional food sources.
Extraction of resveratrol and piceatannol from irradiated sugarcane billets or fiber for use as dietary supplements or ingredients in foods, beverages, or medicines.
Processing stilbene-rich sugarcane into sugar or sugarcane juice to deliver health-promoting stilbenes without alcohol.
Utilization of stilbene-enriched sugarcane bagasse as a dietary fiber supplement or as a feedstock for biofuel production.
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