Instrumental Texture Profile of Traditional Varieties of Tomato (Solanum lycopersicum L.) and its Relationship to Consumer Textural Preferences.

Among components of the consumer's perception of tomato fruit quality, texture is one of the most critical, being formed of a number of attributes that are difficult to evaluate and which change during fruit ripening and storage. The present work relates different textural parameters measured in a collection of traditional tomatoes from Madrid with the appreciation collected from consumer opinions. Texture traits were highly variable in studied tomatoes; they had strong environmental influence and they differed among genotypes. Great intrapopulational variability has been also detected, probably due to the heterogeneity of its fruit tissues and the intrapopulational diversity of studied landraces. Textural behavior of tomatoes affected the level of consumer appreciation. In general, consumers preferred firm fruits with soft skin, due to their low level of springiness and resilience. However, different taster groups have demonstrate how diversity appears to be necessary to satisfy different types of consumers. Among the three groups of consumers which have been identified in this study, the majority (83% of them) preferred local tomato varieties. In addition, heirloom tomatoes presented softer skins than the commercial hybrid reference (values of 0.29 ± 0.19 vs. 0.49 ± 0.12 kg regarding skin rupture force). That circumstance, which is involved in the post-harvest behavior, must be further considered in storage and commercialization.

Effect of the lactose source on the ultrasound-assisted enzymatic production of galactooligosaccharides and gluconic acid.

It is well known that one of the main problems in galactooligosaccharide production (GOS) via tranglycosylation of lactose is the presence of monosaccharides that contribute to increasing the glycaemic index, as is the case of glucose. In this work, as well as studying the effect of ultrasound (US) on glucose oxidase (Gox) activation during gluconic acid (GA) production, we have carried out an investigation into the selective oxidation of glucose to gluconic acid in multienzymatic reactions (ß-galactosidase (ß-gal) and Gox) assisted by power US using different sources of lactose as substrate (lactose solution, whey permeate, cheese whey). In terms of the influence of matrix on GOS and GA production, lactose solution gave the best results, followed by cheese whey and whey permeate, salt composition being the most influential factor. The highest yields of GOS production with the lowest glucose concentration and highest GA production were obtained with lactose solution in multienzymatic systems in the presence of ultrasound (30% amplitude) when Gox was added after 1 h of treatment with ß-gal. This work demonstrates the ability of US to enhance efficiently the obtainment of prebiotic mixtures of low glycaemic index.

Metabolism of biosynthetic oligosaccharides by human-derived Bifidobacterium breve UCC2003 and Bifidobacterium longum NCIMB 8809.

This work aimed to investigate the ability of two human-derived bifidobacterial strains, i.e. Bifidobacterium breve UCC2003 and Bifidobacterium longum NCIMB 8809, to utilize various oligosaccharides (i.e., 4-galactosyl-kojibiose, lactulosucrose, lactosyl-oligofructosides, raffinosyl-oligofructosides and lactulose-derived galacto-oligosaccharides) synthesized by means of microbial glycoside hydrolases. With the exception of raffinosyl-oligofructosides, these biosynthetic oligosaccharides were shown to support growth acting as a sole carbon and energy source of at least one of the two studied strains. Production of short-chain fatty acids (SCFAs) as detected by HPLC analysis corroborated the suitability of most of the studied novel oligosaccharides as fermentable growth substrates for the two bifidobacterial strains, showing that acetic acid is the main metabolic end product followed by lactic and formic acids. Transcriptomic and functional genomic approaches carried out for B. breve UCC2003 allowed the identification of key genes encoding glycoside hydrolases and carbohydrate transport systems involved in the metabolism of 4-galactosyl-kojibiose and lactulosucrose. In particular, the role of ß-galactosidases in the hydrolysis of these particular trisaccharides was demonstrated, highlighting their importance in oligosaccharide metabolism by human bifidobacterial strains.

Enzymatic Synthesis and Structural Characterization of Theanderose through Transfructosylation Reaction Catalyzed by Levansucrase from Bacillus subtilis CECT 39.

This work addresses the high-yield and fast enzymatic production of theanderose, a naturally occurring carbohydrate, also known as isomaltosucrose, whose chemical structure determined by NMR is α-d-glucopyranosyl-(1 → 6)-α-d-glucopyranosyl-(1 → 2)-ß-d-fructofuranose. The ability of isomaltose to act as an acceptor in the Bacillus subtilis CECT 39 levansucrase-catalyzed transfructosylation reaction to efficiently produce theanderose in the presence of sucrose as a donor is described by using four different sucrose:isomaltose concentration ratios. The maximum theanderose concentration ranged from 122.4 to 130.4 g L-1, was obtained after only 1 h and at a moderate temperature (37 °C), leading to high productivity (109.7-130.4 g L-1h-1) and yield (up to 37.3%) values. The enzymatic synthesis was highly regiospecific, since no other detectable acceptor reaction products were formed. The development of efficient and cost-effective procedures for the biosynthesis of unexplored but appealing oligosaccharides as potential sweeteners, such as theanderose, could help to expand its potential applications which are currently limited by their low availability.

Extraction of bioactive carbohydrates from artichoke (Cynara scolymus L.) external bracts using microwave assisted extraction and pressurized liquid extraction.

Microwave assisted extraction (MAE) and pressurized liquid extraction (PLE) methods using water as solvent have been optimized by means of a Box-Behnken and 3(2) composite experimental designs, respectively, for the effective extraction of bioactive carbohydrates (inositols and inulin) from artichoke (Cynara scolymus L.) external bracts. MAE at 60 °C for 3 min of 0.3 g of sample allowed the extraction of slightly higher concentrations of inositol than PLE at 75 °C for 26.7 min (11.6 mg/g dry sample vs. 7.6 mg/g dry sample). On the contrary, under these conditions, higher concentrations of inulin were extracted with the latter technique (185.4 mg/g vs. 96.4 mg/g dry sample), considering two successive extraction cycles for both techniques. Both methodologies can be considered appropriate for the simultaneous extraction of these bioactive carbohydrates from this particular industrial by-product. To the best of our knowledge this is the first time that these techniques are applied for this purpose.

New methodologies for the extraction and fractionation of bioactive carbohydrates from mulberry (Morus alba) leaves.

Pressurized liquid extraction (PLE) was applied for the first time to extract bioactive low molecular weight carbohydrates (iminosugars and inositols) from mulberry ( Morus alba ) leaves. Under optimized conditions, PLE provided a similar yield to the conventional process used to extract these bioactives, but in less time (5 vs 90 min). To remove carbohydrates that interfere with the bioactivity of iminosugars from PLE extracts, two fractionation treatments were evaluated: yeast ( Saccharomyces cerevisiae ) incubation and cation-exchange chromatography (CEC). Both methods allowed complete removal of major soluble carbohydrates (fructose, glucose, galactose, and sucrose), without affecting the content of mulberry bioactives. As an advantage over CEC, the yeast treatment preserves bioactive inositols, and it is an affordable methodology that employs food grade solvents. This work found PLE followed by yeast treatment to be an easily scalable and automatable procedure that can be implemented in the food industry.

Optimisation of a biotechnological procedure for selective fractionation of bioactive inositols in edible legume extracts.

BACKGROUND: Currently, disorders such as diabetes mellitus, obesity or atherosclerosis are recognised as major global health problems. The use of inositols for treating these illnesses has attracted considerable attention and their extraction from natural sources presents added value as they are considered bioactive ingredients in the food industry. Legumes are natural and rich sources of inositols; however, the co-existence of other low molecular weight carbohydrates (LMWCs) in their extracts, which interfere in their bioactivity, might constitute an important drawback, thereby making their removal essential. RESULTS: LMWCs, including inositols, methyl-inositols and glycosyl-inositols of different legume extracts, were determined by GC-MS; the presence of bornesitol (2.35 mg g(-1) ) and lathyritol (0.27 mg g(-1) ) were reported for the first time in grass peas. The use of Saccharomyces cerevisiae for the selective removal of interfering carbohydrates was optimised. Incubation time (3-40 h) was highly dependent on the composition of the legume considered; inositol contents were generally stable along the treatment. CONCLUSION: Removal of interfering LMWCs from inositol-enriched extracts was successfully achieved using a clean and easily scalable fractionation methodology. This biotechnological procedure not only represents high interest for the production of bioactive food ingredients but for applications in other research areas.

Determination of free inositols and other low molecular weight carbohydrates in vegetables.

Different low molecular weight carbohydrates including saccharides, polyalcohols, sugar acids, and glycosides have been identified and quantified in different edible vegetables from Asteraceae, Amarantaceae, Amarylidaceae, Brassicaceae, Dioscoreaceae, and Solanaceae families by gas chromatography-mass spectrometry. Apart from glucose, fructose, and sucrose, other saccharides such as sedoheptulose in chicory, spinach, cabbage, purple yam, eggplant, radish, and oak leaf lettuce, rutinose in eggplant skin, and a glycosyl-inositol in spinach have been identified. chiro-Inositol was found in all vegetables of the Asteraceae family (3.1-32.6 mg 100 g(-1)), whereas scyllo-inositol was detected in those of purple yam, eggplant, artichoke, chicory, escarole, and endive (traces-23.2 mg 100 g(-1)). α-Galactosides, kestose, glucaric acid, and glycosyl-glycerols were also identified and quantified in some of the analyzed vegetables. Considering the bioactivity of most of these compounds, mainly chicory leaves, artichokes, lettuces, and purple yam could constitute beneficial sources for human health.