Presented at the First Biennial World Conference on Recent
Development in Sugar Technologies, May 16-17, 2002 Florida, USA
Antioxidant Properties of Sugarcane Extracts
Dr. Michael Saska, Professor
Audubon Sugar Institute
LSU Agricultural Center
Baton Rouge, LA, USA
Dr. Chung Chi Chou, President, Dr. Chou technologies, Inc.
Visiting professor, South China University of technology
Website : esugartech.com
The role of dietary antioxidants in protecting tissues and cells against harmful effects of free radicals has been widely publicized (Weller, 1999) and numerous preparations extracted from natural sources are available to the public as dietary supplements (Prior and Cao, 1999). A purified extract of bilberry, for example, rich in anthocyanins, was found to be effective in human subjects for reducing the clinical symptoms of lowered capillary resistance and increased retinal sensitivity. Extracts of strawberry and spinach were found to enhance the age-related functions of brain in rats, while blueberry extracts reduced the lung damage in rats subjected to pure oxygen. Extracts of green tea, Gingko biloba, grape seed and many others, and their therapeutic effects, are well known.
Table I: Antioxidant properties (ORAC values inƒÝmole TE/100 g) of various highantioxidant fruits and vegetables (Weller, 1999)
Blackstrap molasses, a byproduct of processing of sugarcane have long been touted for their therapeutic values, mineral contents, etc, albeit with little or no verifiable evidence of biological effects, and are widely available through the health food industry.
Physiological effects of four types sugar cane extracts have been described recently by Japanese researchers (Nagai etal, 2001; Koge etal, 2002), viz. promotion of resistance against viral and bacterial infections, stimulation of immune response, protection against liver injuries, free radical scavenging activity and growth promotion in chickens.
Oxygen Radical Absorbance Capacity (ORAC) of Sugarcane Products and Extracts
ORAC (Cao etal, 1993, 1995), a quantitative method of measuring the antioxidant activity of plasma, foods, natural extracts, etc. has become a standard, although not unique, method over the last five years and ORAC values, in ƒÝmole TE, Trolox (a soluble analogue of Vitamin E, used as a standard) equivalents per 100 g are available in the literature (Table I) for a number of common fruits, vegetables and other antioxidant rich food supplements. In addition, a more recent refinement has been the differentiation between "fast", "slow" and total or "whole" antioxidant capacity, referred to in the following, respectively, as "95% ORAC", "50% ORAC" and "whole ORAC" (Genox, 2001).
Five common edible molasses products (Table II) available on the U.S.market have been selected and characterized by their composition and antioxidant capacity (Tables II and III). Products A – D are sugarcane-based products, while E is a corn liquor-based product with a minor amount of sugarcane based liquor blended in.
Table II: Five edible molasses products available in the US retail market.
Sample RDS Sucrose Glucose Fructose Ash Color
Of the sugarcane products A – D, only B, based on its high color and sugar composition, corresponds to "blackstrap" molasses, the others are lower color products with higher contents of sugars and lower ash.
The antioxidant capacity of the five products correlates very well with their color (Figure 1) as the high antioxidant polyphenol components form a large part of the sugarcane color bodies. With some variations the "95%" and "50%" ORAC values are much lower than the "whole" ORAC, indicating that a substantial part of the antioxidant capacity is from components with very slow-acting functionality
Figure 1: Antioxidant capacity of the five edible molasses products correlates well with their color.
Blackstrap molasses is a final product of sugarcane processing, that has been subjected to a number of unit operations, and a possibility exists that some of the antioxidant activity has been lost in the process. Samples of Louisiana sugarcane juice and syrups, i.e. sugarcane juice clarified with two different procedures and concentrated under vacuum were therefore analyzed (Table V). These products have only been subjected to juice extraction, vacuum concentration and, in the case of syrups, to a pH adjustment and settling, and are products with about 80 % sucrose on dry solids and a color of about 15,000 ICUMSA units. The ORAC values found are substantially higher than those of the edible molasses and identical for the concentrated juice and syrups, indicating that neither the lime nor soda ash clarification measurably reduced the antioxidant capacity.
Table V: Antioxidant capacity of Louisiana sugarcane juice and syrup.
ORAC units per 100 g dry solids.
As even prolonged heating of another sample of Louisiana syrup (Table VI) did not result in any reduction of its antioxidant capacity, the high antioxidant capacity of the syrup samples that does not conform to the pattern observed in Figure 1 is yet unexplained. Geographical or varietal differences of sugarcane composition, contact with metal surfaces, air or process chemicals in the industrial process or other factors may be responsible.
Application of granulated activated carbon, bone char, ion exchange resins, crystallization and chromatographic method for separation of colorants, including polyphenols and flavonoids from sugarcane liquors are well established industrial processes. Therefore, some of these processes were explored to concentrate the antioxidant rich compounds contained in the sugarcane juices. An example of such an application is in Table VII, where the antioxidant capacity is given of a syrup and two kinds of extracts or concentrates. While the concentrate 1 exhibits only a minor improvement over the source/original syrup, the concentrate 2 is a very antioxidant-rich product. The very high proportion of the "fast" antioxidant capacity is remarkable, and augurs well for its therapeutic potential.
The whole ORAC capacity of the concentrate 2 is comparable to such well known antioxidants as caffeic and gallic acids, and exceeds that of many existing commercial antioxidant supplements (Prior and Cao, 1999), and, by a factor of one hundred or more of such health food favorites (Table I) as prunes. While its physiological functions still need to be established, it is believed that this natural extract could be produced, as a new natural or even organic product from sugarcane, at a sufficiently low cost and high volume to aid significantly the antioxidant intake of the population. A 250 mg capsule of this product would satisfy the daily recommended intake of 3,000 ORAC units (Prior and Cao, 1999) considered as minimum to sufficiently increase the serum antioxidant levels.
Cao, G, H. M. Alession and R. G. Cutler, Oxygen-radical absorbance capacity assay for antioxidants, Free Radical Biology and Medicine, Vol. 14, 303 – 311, 1993.
Cao, G, C. P. Verdon, A. H. B. Wu, H. Wang and R. L. Prior, Automated essay of oxygen radical absorbance capacity with the COBAS FARA II, Clin. Chem., 41/12, 1738 – 1744, 1995.
Genox, Oxygen Radical Absorption Capacity Assay for measuring antioxidant activity, ORAC Corporation, October 2001.
Koge, K., Y. Nagai, T. Ebashi, H. Iwabe, M. El-Abasy, M. Motobu, K. Shimura and Y. Hirota, Physiological functions of sugar cane extracts. I> Growth promotion, immunopotentiation and ant-coccidial infection effects in chickens. Proc. 61st Annual Meeting of Sugar Industry Technologists, Delray Beach, FL, May, 2002.
Nagai, Y., T. Mizutani, H. Iwabe, S. Araki and M. Suzuki, Physiological functions of sugar cane extracts, Proc. 60th Annual Meeting of Sugar Industry Technologists, Taipei, Taiwan, May, 2001.
Prior, R. L. and G. Cao, Variability in dietary antioxidant related natural product supplements: The need for methods standardization. Journal of the American Nutraceutical Association, Vlo. 2, No. 2, 46 – 56, 1999.
Weller, K. Can foods forestall aging, Agricultural Research, February 1999.
ORAC analyses and useful comments are gratefully acknowledged of Dr. Rama Rathnam, Director, Genox Corporation, 1414 Key Highway, Baltimore, MD 21230.