Yacon [Smallanthus sonchifolia (Poepp. et Endl.) H. Robinson] chemical composition and use - a review

Abstract

Yacon [Smallanthus sonchifolia (Poepp. et Endl.) H. Robinson], a native plant of the Andes, belongs to the family Compositae (Asteraceae) and it represents a traditional crop of the original population of Peru used in traditional medicine. A major portion of tuberous root biomass is composed of water (> 70% of fresh weight). Saccharides, especially oligofructans, form 70-80% of dry weight, protein content ranges between 0.3% and 3.7%. Fructooligosaccharides of inulin type β (2→1), mainly oligomers (GF 2 -GF 16 ), are known for their ability to keep the colon healthy. Yacon sweetness is predominantly caused by fructose, which is by some 70% sweeter than sucrose. Other oligosaccharides are 1-kestose and nystose. Diabetics and persons suffering from digestive problems are recommended to consume yacon because its sugars are not available from the small intestine. The mean tuberous root composition per 100 g of fresh matter is 81.3, 13.8, 0.9, 1.0, 0.1 and 1.1 g of water, saccharides, fibre, proteins, lipids and ash, respectively. Mean mineral contents per 100 g of fresh matter are 334, 34, 12, 8.4, 0.4 and 0.2 mg of potassium, phosphorus, calcium, magnesium, sodium and iron, respectively. Vitamins B 1 , B 2 , C, β-carotene and polyphenols in the same weight are present at mean concentrations 0.07, 0.31, 5.0, 0.13 and 203 mg, respectively. Yacon can be considered an industrial crop, particularly as a source of inulin. The used forms are flour, syrup, extract from tuberous roots and moreover leaf extract for the preparation of yacon infusion with hypoglycaemic effect. In yacon leaves di-and sesquiterpenes with protective effects against insects are present, among them mainly ent-kaurenic acid (ent-kaur-16-en-19-oic acid) and its derivative -15-α-angeloyloxy-entkauren-19-oic acid 16-epoxide. Other components are polyphenolic antioxidants, esp. hydroxycinnamic acids and chlorogenic acid. A new antifungal melampolide -sesquiterpene lactone named sonchifolin, as well as three known melampolides, polymatin B, uvedalin and enhydrin, were isolated from leaf extracts of yacon. Three major phytoalexins were isolated: 4'-hydroxy-3'-(3-methylbutanoyl)acetophenone, 4'-hydroxy-3'-(3-methyl-2-butenyl)acetophenone and 5-acetyl-2-(1-hydroxy-1-methylethyl)benzofuran.

Studies of chemical and enzymatic characteristics of Yacon (Smallanthus sonchifolius) and its flours

“…In the in natura yacon pulp, moisture content was close to the values found in the literature, which are between 81.7% and 88.7% (LAGO, 2010;SCHER;NOREÑA, 2009;MARANGONI, 2007).…”

“…It is important to emphasize the probable difference in maturation stage of the yacon analyzed in this study in and that used in the studies described above (LOBO, 2004;VIEGA;FUKE, 2007) since with the ripening of that vegetable, fructans can be hydrolized by enzymatic action originating smaller molecules that possibly were not completely quantified because according to Lajolo and Menezes (2006), low molecular weight fructans are not precipitated in alcohol 78% v/v used in the SDF quantification, and thus the use of a fructan determination method is necessary (QUEMENER; THIBAULT; COUSSEMENT, 1994).…”

“…The PPO and PER enzymes are the main responsible for the fast darkening of the in natura yacon during storage, cutting, or processing (LACHMAN;FERNÁNDEZ;ORSÁK, 2003). Thus, the dehydration of the different parts of the yacon becomes an interesting procedure since they are used as food products.…”

Characterization of powder from the permeate of yacon extract by ultrafiltration and dehydrated by spray drying

“…Zhu et al (2014) studied the activity of polysaccharides from yacon, as natural hypoglycemic agent, due to his inhibitory effect on α-glucosidase. Its large tuberous roots have a pulp similar to sweet potatoes, with sweet taste due to the abundance of carbohydrates such as fructose, glucose, sucrose, and inulin with a degree of polymerization (DP) up to 12 (Lachman;Fernández;Orsák, 2003), consequently recognized as fructooligosaccharide (FOS). In addition, several researchers have mentioned that the use of the yacon tuber as a functional food is gaining interest because it contains antioxidants.…”

“…In addition, a high fraction of its dry biomass is composed of FOS, which are inulin-type oligofructans with prebiotic power (Utami et al, 2013). Furthermore, yacon has a large amount of water, more than 70% of the fresh weight, and its roots do not store carbohydrates as starch, making them potentially beneficial in the diet of individuals with diabetes (Lachman;Fernández;Orsák, 2003). According to Ojansivu, Ferreira and Salminen (2011), the consumption of yacon is recommended for weight control because it has relatively low calorific values.…”