Journal of Food Science & Nutrition Category: Agriculture Type: Mini Review
Asparagus Cultivation Co-Products: From Waste to Chance
- Viera-Alcaide I1, Hamdi A2, Rodríguez-Arcos R1, Guillén-Bejarano R1, Jiménez-Araujo A1*
- 1 Instituto De La Grasa, Consejo Superior De Investigaciones Científicas (CSIC), Pablo De Olavide Universitary Campus, Seville, Spain
- 2 Unite De Physiologie Et De Biochimie De La Reponse Del Plantes Aux Contraintes Abiotiques, FST, Campus Universitaire, Tunisia
*Corresponding Author:Jiménez-Araujo A
Instituto De La Grasa, Consejo Superior De Investigaciones Científicas (CSIC), Pablo De Olavide Universitary Campus, Seville, Spain
Received Date: Feb 18, 2020 Accepted Date: Feb 27, 2020 Published Date: Mar 06, 2020
Asparagus cultivation produces enormous amounts of biomass (leaves, stems, fruits, roots and rhizomes) that currently lacks of economic value at the time that implies an environmental challenge. From the bioeconomy point of view an added-value must be given to these co-products to shift their consideration from waste to chance. They are rich in phytochemicals, such as flavonoids, fructans and saponins, which can be easily extracted and purified by green and environmental friendly processes. Those bioactive extracts are of great interest for several industrial sectors. The exploitation of this biomass will represent an increase in the incomes of asparagus growers and life standard enhancement of rural areas.
Asparagus cultivation co-products; Bioeconomy; Flavonoids; Fructans; Saponins
Asparagus cultivation, both white and green, has increased in recent decades. In the year 2000, about 1x106 ha were dedicated worldwide to its cultivation, while in 2017 the figure increased to 1.6x106 ha . The world's leading asparagus producer is China with more than 85% of total production.
Both aerial (stems, leaves and fruits) and underground (roots and rhizomes) parts are produced as co-products of asparagus farming. Annually, around 6 Tm/ha of aerial parts are discarded. It used to be done by controlled burnings in autumn. However, nowadays this practice has been banned by environmental regulations oriented towards CO2 reduction. Besides, a plantation becomes less productive after 8-10 years of exploitation and, at that moment, they are abandoned. Usually the roots and rhizomes (30-40 Tm/ha) are left in the field. This can have important effects in the dissemination of allelopathic substances  and in the development of fungal infections, especially by Fusarium spp. and therefore in the problem of asparagus decay . This could be the reason why asparagus cannot be re-cultivated in the same field until at least 5 or 6 years later. New cropping approaches have to be designed from the perspective of bioeconomy where these two co-products are turned into feedstock for new and sustainable processes, thus giving added-value to these awkward wastes.
Asparagus spears are very appreciated by consumers due to their low calories and high fiber contents, characteristic flavour and the presence of several phytochemicals (vitamins, fructans, flavonoids, cinnamic acids and saponins) [4-8], responsible for most of healthy properties of asparagus spear consumption. These same phytochemicals can be found both in the aerial and underground parts, but in different amounts than in shoots. Flavonoids, saponins and fructans are the most abundant bioactive compounds in roots, fruits, leaves and stems [9,10]. These compounds could be the key for the valorization of asparagus cultivation co-products.
FLAVONOIDS FROM ASPARAGUS LEAVES AND STEMS
Asparagus spears are among the plant products with the highest antioxidant capacity, which is mainly due to their flavonoid content [4,6]. They constitute one of the most abundant groups of antioxidant compounds within the plant kingdom and are usually found as glycosylated derivatives. In asparagus shoots, flavonoids are mainly derived from three aglycones, quercetin, kaempferol and isorhamnetin [11-13]. These same compounds can be found in the basal portions of spears, discarded prior canning, in a quantity near 3g/Kg dry co-product . Amounts six and three times higher have been found in Asparagus albus  and Asparagus racemosus  aerial parts, respectively. These results suggest that the amount of leaf flavonoids in different species depends of genetic and environmental factors, as it has been also shown for spears [4,12].
Since global market is eager for natural antioxidants with great potential as ingredients in the food industry, the amount of flavonoids described for asparagus leaves makes them valuable for flavonoid extraction and purification. In recent years, this market has generated sales of more than 2 billion dollars per year and forecasts indicate that it will reach 3.25 billion in 2020 . Among the antioxidants, those of natural origin constitute a growing sector because of the escalating number of consumers who demand natural foods and ingredients. But the potentiality of asparagus flavonoids goes further than food industry because they are also promising agents for cancer therapy [17-19] and they have also proved antifungal activity .
FRUCTANS FROM ASPARAGUS ROOTS AND RHIZOME
Fructans are oligo- or polysaccharides whose fundamental component is fructose with a glucose unit at its initial end. They are widely distributed throughout the plant kingdom in both monocots and dicots, as well as in green algae. They can be classified by their molecular weight in fructooligosaccharides, of polymerization degree up to 12 units of fructose and inulin of up to 200 units.
It is widely known health benefits from fructans and their wide application in the formulation of foods . These polymers are considered as dietary fiber and have a prebiotic character as they favor the growth of bifidobacteria and lactobacilli by decreasing that of bacteroides and clostridia in the intestine. It is also widely demonstrated that they improve calcium and magnesium absorption, decrease the level of blood triglycerides and increase immune responses . Fructans have been recognized as GRAS (Generally Recognized as Safe) in the USA and as FOSHU (Food of Specified Health Use) in Japan.
Asparagus spears are commonly known as a prebiotic food . In the asparagus edible portion, the content of fructans depends on the variety, ranging from 0.5 to 2% (dry weight), being similar in canning co-products (0.2-1.5%) . However, in Asparagus genus, fructans are reserve polysaccharides that accumulate in the roots, where it represents about 25% of the fresh weight, although this content varies throughout the vegetative cycle of the plant . The main industrial source of commercial inulin is chicory root (Cichorium intybus L.), the content of which in fructan is very similar to that of asparagus roots (23%) .
From this data, it is easy to conclude that asparagus roots are a frontline feedstock for fructan industrial production and, what is more, asparagus can be considered at the same level of chicory as fructan source.
SAPONINS FROM ASPARAGUS PLANTS
Saponins are a group of phytochemicals, present in numerous plant species, which are classified as triterpenic or steroidal according to the structure of their constituent aglycone . The Asparagus genus is one of the few plant foods containing steroidal saponins that are distributed throughout different organs of the plant, including leaves, stems, fruits and roots . They are also present in asparagus spears and in canning coproducts, but their amount and chemical structure vary depending on genetic, environmental and physiological factors [5,14].
The complexity of the saponin structure (and thereby their diversity of biological activities) depends on the variability of the aglycone structure and the nature and attachment position of the glycosidic moieties. This structural variability is of great interest because little differences could lead to bioactivity modifications [28,29]. For a long time, many plant extracts rich in saponins have been used as foaming agents and emulsifiers in the food industry. However, in recent years, the interest for saponins has increased radically due to the growing evidence of their possible health benefits, mainly due to its hypoglycemic, hypocholesterolemic, anticancer and antifungal activities [10,30-33].
As commented above, saponins are present in different concentrations in the different plant parts of asparagus plant. Hamdi et al. , showed that saponins are concentrated in the rhizomes and fruits of A. albus with levels of more than 50g/Kg dry weight. In A. racemosus the quantified amount was 12g/Kg dry roots  and in Asparagus adscendens the concentration varied between 4.5-52g/Kg dry roots . Taking into account the important and varied bioactive functions of these compounds, asparagus roots could become a valuable agricultural co-product. In fact, saponins can be easily extracted and purified from the basal portions of spears (canning co-products) by an environment friendly process . By this patented procedure, both flavonoid and saponin fractions can be effectively separated by adsorption resins. Asparagus roots, being richer in saponins than the studied co-product and lacking in flavonoids, could also be subjected to that process to obtain a more concentrated saponin extract to be applied in different sectors of pharmaceutical and food industries.
Asparagus cultivation co-products must be considered as excellent sources of a range of bioactive compounds of great interest for several industrial sectors. Flavonoids, natural antioxidants, can be isolated from leaves and stems; fructans, widely known as prebiotics, are the main component in asparagus roots and rhizomes; and saponins, with important and varied functional properties, are present in the different plant parts, but especially in roots and fruits. Thanks to this knowledge, the left over biomass from asparagus can swap its present consideration as environmental and soil health challenge for another one, more promising, as feedstock for new industrial activities. This approach could broaden the business opportunities for asparagus spear growers, opening up new opportunities to improve the quality of life in rural areas and preventing depopulation of these endangered regions.
This work was supported by the Tunisian Ministry of Scientific Research and Technology and by the Ministerio de Ciencia e Innovación of Spain (AGL2017-82428-R).
CONFLICT OF INTEREST
The authors declare no conflict of interest.
- Yeasmin R, Motoki S, Yamamoto S, Nishihara E (2013) Allelochemicals inhibit the growth of subsequently replanted asparagus (Asparagus officinalis). Biol Agric Hortic 29: 165-172.
- Elmer WH (2015) Management of Fusarium crown and root rot of asparagus. Crop Prot 73: 2-6.
- Fuentes-Alventosa JM, Jaramillo S, Rodríguez-Gutiérrez G, Cermeño P, Espejo JA, et al. (2008) Flavonoid Profile of Green Asparagus Genotypes. J Agric Food Chem 56: 6977-6984.
- Vázquez-Castilla S, Jaramillo-Carmona S, Fuentes-Alventosa JM, Jiménez-Araujo A, Rodríguez-Arcos R, et al. (2013) Saponin profile of green asparagus genotypes. J Agric Food Chem 61: 11098-11108.
- Ku YG, Bae JH, Namie?nik J, Barasch D, Nemirovski A, et al. (2018) Detection of bioactive compounds in organically and conventionally grown asparagus spears. Food Anal Methods 11: 309-318.
- Chin CK, Garrison SA (2008) Functional elements from asparagus for human health. Acta Hortic 776: 219-226.
- Benkeblia N, Yoshida N, Ooi Y, Nagamine T, Onodera S, et al. (2008) Variations of carbohydrate content and invertase activity in green and white asparagus spears-effects of spear length and portion. Acta Hortic 776: 459-464.
- Pressman E, Schaffer AA, Compton D, Zamski E (1993) Seasonal changes in the carbohydrate content of two cultivars of asparagus. Sci Hortic 53: 149-155.
- Hamdi A, Jaramillo-Carmona S, Srairi Beji R, Tej R, Zaoui S, et al. (2017) The phytochemical and bioactivity profiles of wild Asparagus albus L. plant. Food Res Int 99: 720-729.
- Maeda T, Kakuta H, Sonoda T, Motoki S, Ueno R, et al. (2005) Antioxidation capacities of extracts from green, purple and white asparagus spears related to polyphenol concentration. Hort Sci 40: 1221-1224.
- Rodríguez R, Jaramillo S, Rodríguez G, Espejo JA, Guillén R, et al. (2005) Antioxidant Activity of Ethanolic Extracts from Several Asparagus Cultivars. J Agric Food Chem 53: 5212-5217.
- Guillén R, Rodríguez R, Jaramillo S, Rodríguez G, Espejo JA, et al. (2008) Antioxidants from asparagus spears: Phenolics. Acta Hortic 776: 247-254.
- Fuentes-Alventosa JM, Jaramillo-Carmona S, Rodríguez-Gutiérrez G, Guillén-Bejarano R, Jiménez-Araujo A, et al. (2013) Preparation of bioactive extracts from asparagus by-product. Food Bioprod Process 91: 74-82.
- Durai Prabakaran K, Vadivu R, Jayshree N (2015) Preliminary phytochemical and in vitro cytotoxic activity of the leaves of Asparagus racemosus (Liliaceae). Int J Pharm Sci 6: 743-748.
- Market Research Store (2015) Global Antioxidants (Natural and Synthetic) Market Set for Rapid Growth, To Reach Around USD 3.25 Billion by 2020. In: Antioxidants (Natural, and Synthetic) Market for Pharmaceuticals, Food & Beverages Sector, Feed Additives, Cosmetics Industry, and Other Applications: Global Industry Perspective, Comprehensive Analysis and Forecast, 2014-2020.
- Jaramillo-Carmona S, López S, Abia R, Rodríguez-Arcos R, Jiménez A, Guillén R, Muriana FJG (2014) Combination of quercetin and kaempferol enhances in vitro cytotoxicity on human colon cancer (HCT-116) cells. Rec Nat Prod 8: 262-271.
- Jaramillo S, Lopez S, Varela LM, Rodriguez-Arcos R, Jimenez A, et al. (2010) The Flavonol Isorhamnetin Exhibits Cytotoxic Effects on Human Colon Cancer Cells. J Agric Food Chem 58: 10869-10875.
- Wang W, Van Alstyne PC, Irons KA, Chen S, Stewart JW, et al. (2004) Individual and interactive effects of apigenin analogs on G2/M cell-cycle arrest in human colon carcinoma cell lines. Nutr Cancer 48: 106-114.
- Rosado-Álvarez C, Molinero-Ruiz L, Rodríguez-Arcos R, Basallote-Ureba MJ (2014) Antifungal activity of asparagus extracts against phytopathogenic Fusarium oxysporum. Sci Hortic 171: 51-57.
- Morris C, Morris GA (2012) The effect of inulin and fructo-oligosaccharide supplementation on the textural, rheological and sensory properties of bread and their role in weight management: A review. Food Chem 133: 237-248.
- Roberfroid MB (2005) Introducing inulin-type fructans. Br J Nutr 93: 13-25.
- Slavin J (2013) Fiber and prebiotics: Mechanisms and health benefits. Nutrients 5: 1417-1435.
- Fuentes-Alventosa JM, Jaramillo-Carmona S, Rodríguez-Gutiérrez G, Rodríguez-Arcosa R, Fernández-Bolaños J, et al. (2009) Effect of the extraction method on phytochemical composition and antioxidant activity of high dietary fibre powders obtained from asparagus by-products. Food Chem 116: 484-490.
- Pressman E, Schaffer AA, Compton D, Zamski E (1993) Seasonal changes in the carbohydrate content of two cultivars of asparagus. Sci Hortic 53: 149-155.
- Nwafor IC, Shale K, Achilonu MC (2017) Chemical composition and nutritive benefits of chicory (Cichorium intybus) as an ideal complementary and/or alternative livestock feed supplement. Sci World J 2017: 1-11.
- Oleszek W, Marston A (2013) Saponins in Food, Feedstuffs and Medicinal Plants. Kluwer Academic Publishers. London, UK.
- Mimaki Y, Yokosuka A, Kuroda M, Sashida Y (2001) Cytotoxic activities and structure-cytotoxic relationships of steroidal saponins. Biol Pharm Bull 24: 1286-1289.
- Hernández JC, León F, Brouard I, Torres F, Rubio S, et al. (2008) Synthesis of novel spirostanic saponins and their cytotoxic activity. Bioorg Med Chem 16: 2063-2076.
- Hamdi A, Jime?nez-Araujo A, Rodríguez-Arcos R, Jaramillo-Carmona S, n-Bejarano RG, et al. (2018) Asparagus saponins: Chemical characterization, bioavailability and intervention in human health. Nutri Food Sci Int J 7: 26-36.
- Vázquez-Castilla S, de la Puerta Vázquez R, García Giménez MD, Fernández-Arche MA, Guillén-Bejarano R (2013) Bioactive constituents from "Triguero" asparagus improve the plasma lipid profile and liver antioxidant status in hypercholesterolemic rats. Int J Mol Sci 14: 21227-21239.
- Ji Y, Ji C, Yue L, Xu H (2012) Saponins isolated from Asparagus induce apoptosis in human hepatoma cell line HepG2 through a mitochondrial-mediated pathway. Curr Oncol 19: 1-9.
- Jaramillo S, Muriana FJG, Guillen R, Jimenez-Araujo A, Rodriguez-Arcos R, et al. (2016) Saponins from edible spears of wild asparagus inhibit AKT, p70S6K, and ERK signaling, and induce apoptosis through G0/G1 cell cycle arrest in human colon cancer HCT-116 cells. J Funct Foods 26: 1-10.
- Onlom C, Nuengchamnong N, Phrompittayarat W, Putalun W, Waranuch N, et al. (2017) Quantification of saponins in Asparagus racemosus by HPLC-Q-TOF-MS/MS. Nat Prod Commun 12: 1-7.
- Shah S, Manivel P, Singh R, Dhanani T, Kumar S (2018) Variation of saponin content in asparagus adscendens germplasms from western Himalayan region of India using high performance liquid chromatography-evaporative light scattering detector. J Pharm Appl Chem 4: 139-145.
- Guillén-Bejarano R, Rodríguez-Gutiérrez G, Fuentes-Alventosa JM, Jaramillo-Carmona S, Rodríguez-Arcos R, et al. (2012) Procedimiento de obtención de compuestos funcionales de origen vegetal. Patent number ES2387279A1. CSIC.
Citation:Viera-Alcaide I, Hamdi A, Rodríguez-Arcos R, Guillén-Bejarano R, Jiménez-Araujo A (2020) Asparagus Cultivation Co-Products: From Waste to Chance. J Food Sci Nutr 6: 057.
Copyright: © 2020 Viera-Alcaide I, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.