Dependence of fructooligosaccharide content on activity of fructooligosaccharide-metabolizing enzymes in yacon (Smallanthus sonchifolius) tuberous roots during storage

ABSTRACT:  Tuberous roots of yacon ( Smallanthus sonchifolius ) accumulate about 10%, on a fresh weight basis, of inulin-type fructooligosacharides (FOSs), known as a food ingredient with various healthy benefits. However, we have a great difficulty to ensure these benefits because FOSs with a lower degree of polymerization (DP) decreased remarkably, and fructose increased when the tuberous roots were stored after harvesting even under previously recommended storage conditions of low temperature with high humidity. In the present study, to elucidate the involvement of FOS-metabolizing enzymes in FOS reduction during storage at 90% relative humidity and 8°C, we extracted a crude protein from yacon tuberous roots and measured the activities of invertase (β-fructofuranosidase, EC 3.2.1.26), sucrose:sucrose 1-fructosyltransferase (1-SST, EC 2.4.1.99), fructan:fructan 1-fructosyltransferase (1-FFT, EC 2.4.1.100), and fructan 1-exohydrolase (1-FEH, EC 3.2.1.80). The enzyme activities acting on sucrose, both invertase and 1-SST, were weakened after storage for a month. In addition, the activity of 1-FEH acting on short FOSs such as 1-kestose (GF₂) and 1-nystose (GF₃) was higher than that of 1-FFT. These results suggest that the continuous decline in FOSs of low DP during storage was dependent mainly on the 1-FEH activity. On the other hand, FOSs with a DP of ≥ 9 only slightly decreased in stored yacon tuberous roots during storage, though distinct 1-FEH activity was observed in vitro toward a high-DP inulin-type substrate, indicating that highly polymerized FOSs content was unlikely to be closely connected with the 1-FEH activity.     

Non-structural carbohydrates in processed soft fried onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.)

The effects of curing, removal of top and root, peeling, storage of raw and peeled onion on the content of non-structural carbohydrates and the ability of onion to develop a brown colour were studied. Glucose, fructose, sucrose, 1-kestose, neokestose, nystose, 1^F--d-fructofuranosylnystose and four unknown oligofructosides were quantified using high performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). Field drying affected the concentration of fructose only. Glucose, fructose and an unknown fructan decreased in concentration while the concentration of, e.g. 1-kestose, neokestose and nystose increased by removal of root and top of the onions when stored at 15 °C for one week. Peeling had minor influence on changes in non-structural carbohydrates. Storage of non-peeled (raw) onions at 5 °C and storage of mechanically damaged and peeled onion at 20 °C promoted fructan hydrolysis and browning of soft fried onion. Similar changes were produced by long-term storage of cultivars of common onion. Dry matter and fructose increased during storage of peeled onions at both 5 and 20 °C. The increase in fructose content during storage was due to a significantly decrease in the content of 1-kestose, neokestose, 1^F--d-fructofuranosylnystose, an unknown fructan and total fructans. It was concluded that the missing ability of industrially processed onions to develop a brown colour may be overcome by storage of the peeled onions for a few hours or even overnight at 5 °C.     

Variation in 1‐fructo‐exohydrolase (1‐FEH) and 1‐kestose‐hydrolysing (1‐KH) activities and fructo‐oligosaccharide (FOS) status in onion bulbs. Influence of temperature and storage time

Effects of storage temperature and duration on 1‐fructo‐exohydrolase (1‐FEH) and 1‐kestose‐hydrolysing (1‐KH) activities and trisaccharide (Tri) and fructo‐oligosaccharide (FOS) status in onion bulbs var Tenshin kept for 24 weeks at 10 and 20 °C were investigated. 1‐FEH activity peaked sharply after 10 weeks and seemed to be triggered by a decrease in sucrose content. 1‐KH activity increased during the first 8 weeks and remained stable during the last 8 weeks. Contents of Tri, FOS and total FOS decreased abruptly during the first 8 weeks; however, at 10 °C, contents of Tri, FOS (DP 3–12) and total FOS were lower than those at 20 °C. The consumption rate of fructo‐oligosaccharides also appeared to be higher at 20 °C than at 10 °C, despite the slight degradation in activities observed at this low temperature. 1‐FEH seems to be under the control of a triggering signal which induces its activity, and sucrose seems to be this biochemical signal which initiates dormancy release and the onset of sprouting, as found previously. Thus changes in carbohydrates seem to be a strong indicator of the end of the dormant state of the bulb and the beginning of the sprouting period. Copyright © 2004 Society of Chemical Industry     

Nutritional and functional characterisation of Andean chicuru (Stangea rhizanta)

A thorough functional and nutritional characterisation of Andean chicuru (Stangean rhizanta) root demonstrated its potential as an alternative source of fructooligosacharides (FOS), phenolic compounds, natural antioxidants and minerals. FOS of the GFn type with a degree of polymerisation (DP) of 3 (1-kestose) and 4 (nystose) were present. Important phenolic content and antioxidant activity values were obtained. The main phenolic compounds revealed by HPLC-DAD were caffeic and chlorogenic acids and their respective derivatives as well as flavan-3-ol derivatives. The nutritional analysis revealed high calcium and iron values, as well as considerable amounts of soluble and insoluble dietary fibre. The presence of low DP FOS, together with the high calcium and iron contents in chicuru, might favour its use for industrial applications.     

Study of total fructan and fructooligosaccharide content in different onion tissues

The objective of this work was to determine the fructan and fructooligosaccharide (FOS) content of different onion tissues in order to evaluate the potential use of onion by‐products from the food industry as a source of FOS and fructans. Assays with two methods were carried out to optimise the extraction procedure. The main FOS, namely kestose (GF₂), nystose (GF₃) and fructofuranosylnystose (GF₄), were measured directly using standard sugars. The method for total fructans was based on enzymatic treatment (Novozym 230) of ethanolic/aqueous extract followed by determination of released fructose and glucose by HPLC. Data showed a clear predominance of GF₂ in every onion tissue and no occurrence of highly polymerised fructans. The tissues richest in fructans were the fleshy layers, so that the outer two fleshy layers turn out to be the best onion by‐product as a possible fructan source. © 2000 Society of Chemical Industry     

Fructo-oligosaccharides in table grapes and response to storage

Fructo-oligosaccharides (FOS) have been recognized as health food ingredients with a protective effect against environmental stresses in plants. We have analyzed the profiles of individual FOS in Cardinal table grape pulp, until now undetected, and quantified their changes in response to low temperature and high CO₂ levels. FOS separation and quantification was carried out using anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), and the glucose, fructose and sucrose content of the grapes was also determined. Five FOS were identified and quantified: 1-kestose, neokestose, nystose, nystose b and kestopentaose. While in non-treated table grapes the endogenous FOS remained at steady state levels during storage at 0 °C, exposure to 20% CO₂ for 3 days significant increases the levels of 1-kestose and kestopentaose, members of the inulin series. Considering the competitive advantage afforded by CO₂-treated grapes, this transitory FOS accumulation could provide protection against damage caused by low temperature storage.     

Fructo-oligosaccharide changes during the storage of dehydrated commercial garlic and onion samples

The composition of fructo-oligosaccharides (FOS), together with glucose, fructose and sucrose, has been determined in commercial dehydrated samples of onion ( Allium cepa L.) and garlic ( Allium sativum L.). No qualitative differences were detected among the FOS identified in both onion and garlic. Results show a lower FOS content in garlic than in onion in all samples analysed. In garlic samples, FOS with degree of polymerisation from 3 to 7 were identified and quantified for the first time. In addition, a study on the effect of the storage in these carbohydrates has been carried out under controlled conditions (50 °C, a _w 0.44). The storage seemed to promote important changes in the content of glucose and fructose, which could participate in the Maillard reaction and in the composition of sucrose and FOS, whose hydrolysis was noticeable during the storage time. Therefore, all these chemical changes should be considered to evaluate the quality of these foods.     

KINETICS AND HYDROLYSIS PARAMETERS OF TOTAL FRUCTOOLIGOSACCHARIDES OF ONION BULBS: EFFECTS OF TEMPERATURE REGIMES AND CULTIVARS

This work studied the percentage of hydrolysis, observed hydrolysis rate constant (k_obs), half‐life time (t_1/2) and kinetics of degradation of the total fructooligosaccharides (FOS) of three different onion bulb cultivars (Yellow Spanish, Red Amposta and Tenshin) kept during 6 months under three temperature regimes, 10, 15 and 20C. The percentage of hydrolysis of FOS was higher at 20C than at 10C and ranged from 47 to 58% at 10C, from 63 to 68% at 15C and from 74 to 83% at 20C. The k_obs ranged from 27 × 10^?3 to 36 × 10^?3/week at 10C and from 41 × 10^?3/week to 47 × 10^?3/week at 15C, while at 20C, it was high and was about k_obs 56 × 10^?3/week.. The t_1/2 decreased when temperature increased, and varied from 19.5 to 26.0 weeks at 10C, from 14.6 to 16.8 weeks at 15C and from 9.4 to 12.3 weeks at 20C, indicating that high degree of polymerization (DP) FOS have shorter lives than low DP FOS. Linear regression and kinetics of hydrolysis have shown that FOS hydrolysis is higher at 20C, with a coefficient of regression ranging between 0.87 and 0.99. Apparently, FOS hydrolysis is temperature independent, and storage time had more effect on the higher DP FOS than on the lower DP FOS.     

Importance of growth hormones and temperature for physiological regulation of dormancy and sprouting in onions

Onion is one of the most cultivated crops, and its production is increasing worldwide. Proper handling and storage will add huge benefits to the supply of onion to meet the demand of consumers. For storage, it is important to understand onion physiology from the day it was harvested from the field until it reaches the market. This review summarizes the scientific literature related to the physiology of the onion bulb with respect to growth regulators, temperature, and chemical controls. The biochemical changes that occur during dormancy break and sprouting have been discussed in detail. The three main environmental factors that can influence onions during storage are temperature, humidity, and composition of the atmosphere in the storage area. Among these factors, temperature plays a paramount role in the physiology of onion during pre- and postharvest storage. Particular emphasis was given to plant growth hormones (endogenous and exogenous) and their consequent effects with respect to dormancy, sprouting, and biochemical changes that occur in onions.     

Physicochemical Properties of Bread Baked from Flour Blended with Immature Wheat Meal Rich in Fructooligosaccharides

ABSTRACT: Grain of the soft white wheat cultivar Harus was harvested weekly from anthesis to maturity and fructooligosaccharides (FOS) contents were determined by reversed-phase high-performance liquid chromatography. Tests were carried out to determine the effect of adding immature wheat meal to a base flour of cultivar Russ (hard red spring) on the quality characteristics of bread. FOS content was also analyzed in baked bread, and the effect of transglutaminase in improving bread quality was examined. Marked decreases in FOS contents, such as 1-kestose and nystose, were observed with grain maturation. The overall quality of bread appeared to be acceptable, and the added FOS were retained after baking.     

Comparison of the water-soluble carbohydrate composition and fructan structures of Agave tequilana plants of different ages

The composition of water-soluble carbohydrates from Agave tequilana plants of 2, 4 and 6½ years were compared by HPLC, HPAEC-PAD, MALDI-TOF-MS and GC–MS. The plants of 2 years exhibited the highest levels of free monosaccharide and low molecular weight fructans (DP 3–DP 6) with potential application as prebiotics. A maximum of fructan polymerisation was achieved at 4 years with mean DP from 3 to 30, then it was decreased at 6½ years with mean DP from 4 to 24. The linkage analysis showed an increase and decrease in the branching degree from 2 to 6½ years with a maximum at 4 years, correlated to changes in t-β-d-Fruf linkages with increased and decreased synthesis of (2→1) and (2→6)-β-d-Fruf as well as 1,6-di-β-d-Fruf linkages.     

Antidiabetic activity and molecular docking of fructooligosaccharides produced by Aureobasidium pullulans in poloxamer-407-induced T2DM rats

This study evaluated the beneficial effects of fructooligosaccharide (FOS) intake from Aureobasidium pullulans using poloxamer-407 (PX-407) induced type 2 diabetes mellitus (T2DM) in rat. Administration of FOS enhanced enzymatic activities of catalase and glutathione reductase in a dose-dependent manner. Significant reduction in fasting plasma triacylglycerol and very low-density lipoprotein level coupled with slight increase in fasting plasma insulin level was observed. Significant decrease in severe glucosuria, proteinuria, blood creatinine, urea and advanced glycation end products was also observed. Supplementation of FOS increased glucagon like peptide-1 content as well as Bifidobacteria and Lactobacilli populations in the caecum. Molecular docking by Gold and Glide software revealed that three sugar types present in the FOS (1-kestose, nystose, and 1-β-fructofuranosyl nystose) are potent dipeptidyl peptidase-IV inhibitors as well as peroxisome proliferator-activated receptor-gamma agonists. This work indicates that FOS can be positioned as a nutraceutical product, beneficial in diabetes-associated metabolic abnormalities.     

Recent trends in the microbial production,analysis and application of Fructooligosaccharides

This review focuses on the recent developments in the area of FOS research—its microbial production, functional properties and applications and an overview of the different analytical methods for the determination of the FTase. Different microbial sources of FTase reported in literature to produce FOS with different linkages to form 1-kestose, 6-kestose and neokestose in varying yields based on initial sucrose concentration is discussed. Different fermentative methods have been used for production of FOS. SSF has been used for the production of a value added product FOS utilizing various agroindustrial byproducts. The nutritional and culture parameters when optimized, the FOS yields and productivity could be improved. The use of immobilized enzymes and cells has led to the development of effective and economic methods for large-scale production of FOS. Forced flow Membrane reactor systems, biocatalyst system with a bioreactor equipped with a microfiltration systems, have been used for production of high content FOS by removing the released glucose and unreacted sucrose from the reaction mixture resulting in up to 98% FOS. The use of mixed enzyme system of Fructosyl Transferase and glucose oxidase or glucose dehydrogenase, could produce highly concentrated FOS up to 90–98%. Nano-filtration for removing glucose resulted in FOS of 90% concentration. The purified enzyme was found to produce kestose and nystose unlike the crude enzyme which produced GF₅ and GF₆ oligosaccharides Kinetic parameters (V_m, K_m, and K_i) of the enzyme were determined from experimental data on the transfructosylation rate at various substrate concentrations with and without addition of glucose Techniques like HPLC, using polar-bonded phase and resin-based HPLC columns are commonly used for separation of oligosaccharides with refractive Index Detector or pulsed amperometric detector and annular size exclusion chromatography for large scale and continuous fractionation. Other techniques like gas liquid chromatography, thin layer chromatography, NMR and Mass Spectrometry have been used for structure analyses. The functional properties like use as prebiotics, dietary fiber, role in absorption and defense/Immunity, lipid metabolism control of diabetics have been discussed. A variety of applications in food formulations are also discussed.     

Vacuum impregnation of apple slices with Yacon (Smallanthus sonchifolius Poepp. & Endl) fructooligosaccharides to enhance the functional properties of the fruit snack

This work aimed to incorporate prebiotic FOS from yacon in apple slices using vacuum impregnation (VI). Three FOS concentrations (10.3, 14.1 and 18.9 g per 100 g of dry matter (DM)), two temperatures (25 and 35 °C), reuse of extracts and stability of the impregnated slices were evaluated. The highest impregnation level (30.5 g per 100 g DM) was obtained at 35 °C with 14.1% FOS extract while levels of common sugars were reduced. Total phenolics and ABTS antioxidant capacity (AC) slightly decreased while ORAC AC was reduced by 55%. Reuse of the impregnation solution in successive cycles after restoring the FOS level maintained the FOS concentration and profile (GF2–GF7), sugars and phenolic antioxidants. FOS in apple slices remained stable during 4 week storage, while a_w, colour and fracture point changed during storage. This work demonstrated the feasibility of yacon FOS to improve the functional properties of dehydrated apple slices.     

Comparison of Shelf Life of Eggs Coated with Chitosans Prepared under Various Deproteinization and Demineralization Times

Internal quality of eggs coated with chitosans prepared under various deproteinization (DP at 0, 5, 15 min) and demineralization (DM at 0, 10, 20, 30 min) times was evaluated. Chitosans prepared under DP 0 min/DM 30 min, DP 5 min/DM 30 min, and/or DP 15 min/DM 20 min conditions can be effectively used as an egg‐coating material in preserving the internal quality of eggs compared with chitosan prepared under the DP 15 min/DM 30 min condition. The Haugh unit and yolk index values suggested that the chitosan‐coated eggs can be preserved for at least 2 wk longer than the control noncoated eggs during 5 wk of storage at 25°C.     

Viability and activity of bifidobacteria in yoghurt containing fructooligosaccharide during refrigerated storage

The viability of yoghurt bacteria and two commercial strains of bifidobacteria was assessed in either yoghurt containing chicory fructooligosaccharide (FOS) or without any prebiotic, during 28 days storage at 4 °C. All the products showed a decrease in the viable count of yoghurt bacteria and bifidobacteria during storage. Numbers of Lactobacillus delbrueckii ssp. bulgaricus decreased faster than those for Streptococcus thermophilus. The viability of bifidobacteria in yoghurt was affected by the strain type and the presence of FOS. Bifidobacterium animalis exhibited better stability in the yoghurt than B. longum. The recommended level of 1 million cells was exceeded for B. animalis throughout storage. The highest viable number of bifidobacteria (3.59–2.25 × 10⁷ CFU g^?1) was obtained in the product containing B. animalis and FOS. Viability of B. longum in yoghurt containing FOS remained above 10⁶ CFU g^?1 for up to 21 days, whereas this level was maintained for only 7 days for that organism in yoghurt without any prebiotic.     

Flavor Evaluation and Volatile Flavor Constituents of Stored Aseptically Packaged Orange Juice

Samples of commercial orange juice packaged aseptically and stored at 21°C and 26°C were evaluated weekly by a sensory panel using hedonic ratings. Flavor scores were significantly lower than control juice and unacceptable after 1 wk at 26°C and 2 wk at 21°C. The flavor score decreased to 50–60% of the starting value during 6 wk storage. The volatile components, α-terpineol and ethyl acetate, increased during storage. A component not identified earlier as a volatile citrus component was identified as 2-(2-butoxyethoxy)ethanol. This and the observed increase in ethyl acetate during storage might have come from the laminated multilayered package liner. Limonene in juice decreased about 40% during storage. Other major volatile components did not change markedly.     

Consequences of dietary energy source and energy level on energy balance,lactogenic hormones,and lactation curve characteristics of cows after a short or omitted dry period

Omitting the dry period (DP) generally reduces milk production in the subsequent lactation. The aim of this study was to evaluate the effect of dietary energy source—glucogenic (G) or lipogenic (L)—and energy level—standard (std) or low—on milk production; energy balance (EB); lactogenic hormones insulin, insulin-like growth factor 1 (IGF-1), and growth hormone (GH); and lactation curve characteristics between wk 1 and 44 postpartum in cows after a 0-d or 30-d DP. Cows (n = 110) were assigned randomly to 3 transition treatments: a 30-d DP with a standard energy level required for expected milk yield [30-d DP(std)], a 0-d DP with the same energy level as cows with a 30-d DP [0-d DP(std)], and a 0-d DP with a low energy level [0-d DP(low)]. In wk 1 to 7, cows were fed the same basal ration but the level of concentrate increased to 6.7 kg/d for cows fed the low energy level and to 8.5 kg/d for cows fed the standard energy level in wk 4. From wk 8 postpartum onward, cows received a G ration (mainly consisting of corn silage and grass silage) or an L ration (mainly consisting of grass silage and sugar beet pulp) with the same energy level contrast (low or std) as in early lactation. Cows fed the G ration had greater milk, lactose, and protein yields, lower milk fat percentage, greater dry matter and energy intakes, and greater plasma IGF-1 concentration compared with cows fed the L ration. Dietary energy source did not affect EB or lactation curve characteristics. In cows with a 0-d DP, the reduced energy level decreased energy intake, EB, and weekly body weight gain, but did not affect milk production or lactation curve characteristics. A 30-d DP resulted in a greater total predicted lactation yield, initial milk yield after calving, peak milk yield, energy intake, energy output in milk, days to conception [only when compared with 0-d DP(low)], plasma GH concentration [only when compared with 0-d DP(std)], and decreased weekly body weight gain compared with a 0-d DP. A 30-d DP decreased both the increasing and the declining slope parameters of the lactation curve and the relative rate of decline in milk yield (indicating greater lactation persistency) compared with a 0-d DP, and decreased plasma insulin and IGF-1 concentration, and EB. In conclusion, feeding a G ration after wk 7 in milk improved energy intake and milk production, but did not affect EB compared with an L ration. For cows without a DP, a reduced dietary energy level did not affect milk production and lactation curve characteristics, but did decrease EB and weekly body weight gain. A 30-d DP increased milk yield and lactation persistency, but decreased milk fat and protein content, EB, and plasma insulin and IGF-1, compared with a 0-d DP.     

不同质量浓度低聚果糖和低聚半乳糖对发酵乳品质的影响

研究不同质量浓度低聚果糖和低聚半乳糖对发酵乳在发酵期和贮藏期内乳中菌落活菌数、滴定酸度和黏度的影响。结果表明：在发酵期低聚果糖（QHT-90 FOS）对发酵乳中乳酸菌活菌数的增殖作用要显著高于低聚半乳糖（QHT-60 GOS）,在QHT-90 FOS质量浓度为1.5 g/100 mL的样品中,12 h时瑞士乳杆菌（Lactobacillushelveticus）MB2-1活菌数可达到4.44×109 CFU/g,而不同质量浓度和结构的低聚果糖和低聚半乳糖对样品滴定酸度和黏度的影响差异不显著;此外在4 ℃发酵乳贮藏期间,QHT-90 FOS对L. helveticus MB2-1有一定保护作用,在QHT-90 FOS质量浓度为1.5 g/100 mL的样品中,贮藏14 d后,活菌数仅减少11.90%,而滴定酸度基本不变,产品黏度保持在9 000 mPa·s。