Nutritional value and antioxidant activity of the maguey syrup (Agave salmiana and A. mapisaga) obtained through three treatments

During the Pre-Colombian period magueys were used in Mesoamerica for their sap, which is named aguamiel (literally honey water in Spanish). Aguamiel is then fermented into pulque, followed by (in order of importance): textiles, apparel, different thicknesses cords, food (sweetener, syrup, vinegar, flower buds, and cooked immature flowering stalks), firewood and construction materials. The maguey syrup is a product that is traditionally obtained by concentrating the aguamiel by means of an artisanal evaporation treatment (high temperatures, atmospheric pressure and prolonged times). The nutritional and nutraceutical value of this concentrate is unknown despite its wide consumption since pre-Hispanic times in various regions of Mexico. The objective of this work was to evaluate the nutritional value and the content of antioxidant compounds of the maguey syrup obtained from the aguamiel (Agave salmiana and A. mapisaga) through three elaboration treatments (artisanal evaporation, evaporation under reduced pressure and lyophilization). The best species for the production of maguey syrup turned out to be the aguamiel of the A. salmiana due to its nutritional and nutraceutical attributes, higher content of reducing sugars and lower sucrose compared to that of A. mapisaga. The maguey syrup is a sweetener with a higher content of protein (3320 mg 100(-1)) in comparison to bee honey (152.7 mg 100 g(-1)). The maguey syrup obtained by lyophilization (LYT) retained the nutraceutical value; but its antioxidant activity was statistically equal to the syrup obtained by evaporation under reduced pressure (RPT), and the artisanal evaporation treatment (AET) had a decrease in vitamin C content in comparison to LYT and RPT. The syrups obtained by RPT and AET presented different degrees of non-enzymatic darkening, possibly due to the formation of melanoidins (dark pigments). The darkest syrup obtained by AET had the highest antioxidant capacity (987.24 mu M TE 100 g(-1)) associated to a higher content of phenolic compounds (593.74 mg GAE 100 g(-1)).