Stability of fructooligosaccharides, sugars and colour of yacon (Smallanthus sonchifolius) roots during blanching and drying

Abstract

Yacon (Smallanthus sonchifolius) root is an important source of fructooligosaccharides (FOS). This study evaluated the influence of the blanching and drying processes on the sugars, FOS and colour of the obtained flour. Blanching in boiling water of 5 mm slices for 6 min allowed to inactivate 95% of polyphenol oxidase and peroxidase activity. Blanching solutions containing ascorbic, citric and lactic acid were detrimental in terms of FOS retention (68.2-87.4%) due to hydrolysis mainly of GF3, GF4 and GF5 FOS, and also important losses of reducing sugars (RS) were observed (69.5-87.4% retention). Blanching treatments that included ascorbic acid/CaCl 2 prevented RS and FOS losses and improved colour of the obtained flour. The drying tested temperatures of 50-80°C did not affect the RS retention and FOS losses associated to hydrolysis and the use of 80°C rapidly reduced the water content and minimised browning reactions yielding flours with excellent colour characteristics with high FOS content that can be derived to the elaboration of prebiotic containing functional foods or for the extraction and purification of FOS. Drying process evaluationAfter optimisation of the blanching process described above, different drying temperatures were tested that corresponded to 50, 65 and 80°C, respectively, under the same conditions described above. For each corresponding drying temperature, a not blanched control sample was obtained. All treatments were carried out in triplicate. Analysis carried out included water content, RS, FOS and colour. Analytical determinationsWater content was determined in a vacuum oven until constant weight was obtained according to the 925.45-A method (AOAC, 1995). The pH of the blanching solutions and obtained flours was carried out

Effect of Yacon (Smallanthus sonchifolius) fructooligosaccharide purification technique using activated charcoal or ion exchange fixed bed column on recovery, purity and sugar content

“…The roots were processed according to Campos et al . (). Briefly, yacon slices (~ 5 mm) were blanched in boiling water containing 100 ppm ascorbic acid and 0.5% CaCl 2 , and drained and dried in a cabin dryer at 65 °C (Venticell 11 l L, MMM Group, Medcenter Einrichtungen GmbH, München, Germany).…”

Evaluation of plasma, high‐pressure and ultrasound processing on the stability of fructooligosaccharides

“…Thermal processing of FOS, reported by several works (L'Homme et al, 2003a,b;Huebner et al, 2008;Courtin et al, 2009;Campos et al, 2016), showed a significant change in FOS content and high rates of hydrolysis. Courtin et al (2009) reported losses up to 65% of FOS in model solution after 15 min of processing at 100°C.…”

“…Thermal processing of FOS, reported by several works (L'Homme et al ., ,b; Huebner et al ., ; Courtin et al ., ; Campos et al ., ), showed a significant change in FOS content and high rates of hydrolysis. Courtin et al .…”

“…() regarding the influence of the temperature, because it was found that the hydrolysis of FOS decreased with increasing temperature. Studies carried out with blanching of yacon showed that blanching (50–80 °C) has caused the hydrolysis of FOS, reducing the contents of FOS by 13 to 32% depending on the temperature that was applied (Campos et al ., ).…”

“…However, their results differ from the results of Courtin et al (2009) regarding the influence of the temperature, because it was found that the hydrolysis of FOS decreased with increasing temperature. Studies carried out with blanching of yacon showed that blanching (50-80°C) has caused the hydrolysis of FOS, reducing the contents of FOS by 13 to 32% depending on the temperature that was applied (Campos et al, 2016). The insignificant changes found after the different treatments and exposures indicate that these nonthermal processes did not affect the FOS concentration.…”