Synthesis of fructooligosaccharides in banana 'prata' and its relation to invertase activity and sucrose accumulation

Production, modification and degradation of fructans and fructooligosacharides by enzymes originated from plants

Non-starch polysaccharides exhibit numerous beneficial health effects but compounds belonging to FODMAP (Fermentable Oligo- Di- and Monosaccharides and Polyols) has been recently connected to several gastrointestinal disorders. This review presents integrated literature data on the occurrence and types of fructans and fructooligosaccharids (classified as FODMAPs) as well as their degrading enzymes present in plants. Plants from the family Asteraceae and many monocotyledones, including families Poaceae and Liliaceae, are the most abundant sources of both fructans and fructan-degrading enzymes. So far, vast majority of publications concerning the application of these specific plants in production of bakery products is related to increase of dietary fibre content in these products. However, there is limited research on their effect on FODMAP content and fibre balance. The authors emphasize the possibility of application of enzyme rich plant extract in food production casting light on the new scientific approach to fibre modification.

Fructan distribution in banana cultivars and effect of ripening and processing on Nendran banana

Many plants store fructan as reserve carbohydrate. Fructans naturally present in almost all plant foods, are also used as functional ingredients by the food industry to modify the texture and taste due to their properties as gelling agents, fat substitutes, soluble dietary fibers and low calorie sweeteners. Seven banana cultivars were analysed for fructans and Nendran banana was selected for the next set of experiments as it had the highest fructan content (1433.3 mg/100 g) among the cultivars studied. Low temperature ripening (16 °C) of Nendran banana resulted in higher fructan accumulation of these carbohydrates in cold conditions. Pectinase pre-treatment significantly increased yield of total fructans from 1.4/100 g to 6.5 g/100 g i.e., 370 %. Fructan composition was affected by processing, namely steaming and puree preparation in Nendran. The fructan composition data documented in this study will enable including banana, naturally high in fructans in the diet and will facilitate storage and processing for nutritional formulation for higher fructan consumption.

Fructans and other water soluble carbohydrates in vegetative organs and fruits of different Musa spp. accessions

The water soluble carbohydrates (WSC) glucose, fructose, and sucrose are well-known to the great public, but fructans represent another type of WSC that deserves more attention given their prebiotic and immunomodulatory properties in the food context. Although the occurrence of inulin-type fructo-oligosaccharides (FOS) was proposed in the fruit of some banana accessions, little or no information is available neither on the exact identity of the fructan species, nor on the fructan content in different parts of banana plants and among a broader array of banana cultivars. Here, we investigated the WSC composition in leaves, pulp of ripe fruits and rhizomes from mature banana plants of 11 accessions (I to XI), including both cultivated varieties and wild Musa species. High performance anion exchange chromatography with integrated pulsed amperometric detection (HPAEC-IPAD) showed the presence of 1-kestotriose [GF2], inulobiose [F2], inulotriose [F3], 6-kestotriose and 6G-kestotriose (neokestose) fructan species in the pulp of mature fruits of different accessions, but the absence of 1,1-nystose and 1,1,1 kestopentaose and higher degree of polymerization (DP) inulin-type fructans. This fructan fingerprint points at the presence of one or more invertases that are able to use fructose and sucrose as alternative acceptor substrates. Quantification of glucose, fructose, sucrose and 1-kestotriose and principal component analysis (PCA) identified related banana groups, based on their specific WSC profiles. These data provide new insights in the biochemical diversity of wild and cultivated bananas, and shed light on potential roles that fructans may fulfill across species, during plant development and adaptation to changing environments. Furthermore, the promiscuous behavior of banana fruit invertases (sucrose and fructose as acceptor substrates besides water) provides a new avenue to boost future work on structure-function relationships on these enzymes, potentially leading to the development of genuine banana fructosyltransferases that are able to increase fructan content in banana fruits.

Transfructosylation reaction in cured tobacco leaf (Nicotiana tabacum)

Tobacco plant was known to be a non-fructan-storing plant. However, we demonstrated that fructo-oligosaccharides (FOSs) were formed in cured tobacco leaf on adding sucrose to the leaf in our previous report (Nagai et al., J. Agric. Food Chem., 60, 6606-6612, 2012). Also, it was expected from the results obtained in previous study that FOSs were generated by enzymatic reaction in cured tobacco leaf. The purpose of this study is to confirm and understand the mechanisms of above-mentioned FOSs formation. Thus, we tried to purify the enzymes related to the production of FOSs. The enzymes were extracted from pulverized cured tobacco leaf (burley type leaf), and were purified by charcoal treatment, ultrafiltration, and several chromatography techniques. As a result, one of the enzymes was purified up to 414-fold. It was revealed that this enzyme was acid invertase exhibiting maximum transfructosylation activity at pH 6.0, 60 °C. In addition, general properties of this enzyme were also investigated. The enzyme purified in this study enhanced the ratio of FOSs formation under the condition of high concentrated sucrose. From these results, it was suggested that this enzyme participated in the formation of FOSs in tobacco leaf after curing.

Identification of fructo- and malto-oligosaccharides in cured tobacco leaves (Nicotiana tabacum)

Fructo-oligosaccharides (FOSs) and malto-oligosaccharides (MOSs) in cured tobacco leaves ( Nicotiana tabacum ) were detected and quantified using high-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). These oligosaccharides were present in several tobacco materials including flue-cured tobacco, sun/air-cured tobacco, and cut filler of commercially available tobacco products, but were not detected in air-cured tobacco. The changes in these oligosaccharides during storage were also investigated. The results revealed that MOSs simply decreased under a warm atmosphere and FOSs increased. In addition, the formation of FOSs in cured tobacco leaves occurred in the presence of sucrose. With regard to FOSs, it has been reported that green tobacco leaves do not contain FOSs such as kestose, nystose, and fructosyl-nystose. The results of a model test suggested that the changes in FOS amount were caused by enzymatic reactions.