HPLC Determination of Sugars and Starch in Green Beans

A reversed-phase HPLC method using a Spherisorb NH₂ column and 85:15 v/v acetonitrile/water as mobile phase was developed for determination of starch and soluble sugars (glucose, fructose and sucrose) in plants. When applied to pure starch samples, the analytical method was as accurate as the official AOAC method and had better precision (coefficient of variation 0.87% vs 1.27%). When applied to green bean (Phaseolus vulgaris L.), recovery was 97.7% for starch, 98.0% for glucose and 98.1% for both fructose and sucrose.     

Quantitative determination of carbohydrates in orange juice by gas chromatography

 A gas chromatographic method using a capillary column is described for the quantitative analysis of fructose, glucose, sucrose and myo-inositol in orange juice. The method is evaluated for precision and recovery using phenyl-β-glucoside as an internal standard. The results support the suitability of the method. Carbohydrates (fructose, glucose, sucrose and myo-inositol) were determined in different kinds of orange juice. The determination of carbohydrate composition and ratios of the carbohydrate constituents provide a method to assess orange juice quality, especially the myo-inositol content and myo-inositol/fructose ratio. These new indices, which were found to be lower in samples made from concentrates, provide information on the quality and genuineness of orange juice. Received: 10 June 1997     

Quantitative determination of carbohydrates in orange juice by gas chromatography

 A gas chromatographic method using a capillary column is described for the quantitative analysis of fructose, glucose, sucrose and myo-inositol in orange juice. The method is evaluated for precision and recovery using phenyl-β-glucoside as an internal standard. The results support the suitability of the method. Carbohydrates (fructose, glucose, sucrose and myo-inositol) were determined in different kinds of orange juice. The determination of carbohydrate composition and ratios of the carbohydrate constituents provide a method to assess orange juice quality, especially the myo-inositol content and myo-inositol/fructose ratio. These new indices, which were found to be lower in samples made from concentrates, provide information on the quality and genuineness of orange juice. Received: 10 June 1997     

Laboratory evaluation of previously fermented juice as a fermentation stimulant for lucerne silage

The potential use of forage juice anaerobically stored for 2 days (previously fermented juice, PFJ) as a silage additive was investigated. Lucerne (450 g) was ensiled in laboratory‐scale silos (900 ml capacity) with or without sucrose (20 g kg⁻¹) or PFJ (2.5 ml kg⁻¹). Silages treated with both additives were also made and fermentation quality, in vitro dry matter digestibility and in vitro ruminal NH₃ production were determined. The control silage showed very poor quality with high butyrate and NH₃‐N concentrations. Addition of sucrose significantly increased lactate but failed to inhibit the deterioration by clostridial fermentation. Use of PFJ further increased lactate and greatly reduced butyrate and NH₃‐N production during storage. The combination of sucrose and PFJ was more effective in improving fermentation than either additive on its own. In vitro digestibility appeared to be higher when lucerne was well preserved. Ruminal NH₃ production in vitro was decreased in silages with sucrose and PFJ added at ensiling. This result indicates that use of PFJ can be a promising way to stimulate lactate production in some difficult direct cut silage. The potential of improving fermentation may be comparable to conventional sugar additives. © 1999 Society of Chemical Industry     

HPLC Determination of Sugars in Raw and Baked Sweet Potatoes

Isocratic HPLC techniques were developed for the quantitative analysis of sugars in raw and baked sweet potato roots. The major sugars in raw roots: sucrose, glucose, and fructose, were quantitated with a cation exchange resin column (Aminex HPX-87C) heated to 75°C using HPLC-grade H₂O as the mobile phase and refractive index detection. The major sugars in baked roots (convection oven or microwaved) were maltose, sucrose, glucose, and fructose. They were quantitated with an aminopropyl bonded phase column (Bio-Sil Amino 5S) at 21°C using a 70% CH₃CN:30% H₂O mobile phase and refractive index detection. Over 95% recoveries of all sugars added to sweet potato roots were obtained.     

KINETICS OF OSMOTIC DEHYDRATION OF MANGO

The effects of sucrose syrup concentration (40–70 g/100‐g solution) and temperature (40–90C) on water loss and sucrose uptake by mango mesocarp slices during osmotic dehydration were investigated. The effective diffusivities for mass transfer were determined using the slope method based on the Fickian diffusion model. Water loss and sucrose uptake were proportional to the square root of osmotic contact time, implying that the process is Fickian. The specific mass transfer rate constants and effective diffusivities (D_e), derived from Fick's unsteady‐state diffusion equation, increased with temperature and sucrose syrup concentration. D_e values for water loss and sucrose uptake, which ranged between 2.59 × 10^?6 to 5.12 × 10^?6 m²/h and 1.70 × 10^?6 to 4.14 × 10^?6 m²/h, respectively, were related to absolute temperature using an Arrhenius‐type relationship. The activation energies, which fell in the range previously reported for diffusion‐controlled processes, increased with sucrose syrup concentration and varied from 9.74 to15.16 KJ/mol.     

Rheology of Rice Starch‐Sucrose Composites

The effect of sucrose at different concentrations (0, 10, 20 and 30%) on rheological properties of rice starch pastes (5% w/w) was investigated in steady and dynamic shear. The steady shear properties of rice starch‐sucrose composites were determined from rheological parameters for power law and Casson flow models. At 25°C all the starch‐sucrose composites exhibited a shear‐thinning flow behavior (n=0.25–0.44). The presence of sucrose resulted in the decrease in consistency index (K), apparent viscosity (η_a,100) and yield stress (σ_oc). Dynamic frequency sweeps at 25°C indicated that starch‐sucrose composites exhibited weak gel‐like behavior with storage moduli (G′) higher than loss moduli (G′′). G′ and G′′ values decreased with the increase in sucrose concentration. The dynamic (η*) and steady‐shear (η_a) viscosities at various sucrose concentrations did not follow the Cox‐Merz superposition rule. G′ values as a function of aging time (10 h) at 4°C showed a pseudoplateau region at long aging times. In general, the values of G′ and G′′ in rice starch‐sucrose composites were reduced in the presence of sucrose and depended on sucrose concentration.     

A single acute dose of pinitol from a naturally-occurring food ingredient decreases hyperglycaemia and circulating insulin levels in healthy subjects

A limited amount of research suggests that oral ingestion of pinitol (3-O-methyl-d-chiro-inositol) positively influences glucose tolerance in humans. This study assessed the effects of different doses of pinitol supplementation on glucose tolerance, insulin sensitivity and plasma pinitol concentrations. Thirty healthy subjects underwent two one-day trials in which they consumed a nutritive beverage (Fruit Up®) containing 2.5, 4.0 or 6.0 g of pinitol and a corresponding placebo equivalent in both energy and carbohydrates. Blood samples were collected frequently over the 240-min test period. The pinitol-enriched beverage reduced serum glucose and insulin at 45 and 60 min, but only at a dose of 6.0 g. Plasma pinitol concentrations, maximum concentration and AUC increased according to the dose administered. The results show that a single dose of pinitol from a naturally-occurring food ingredient at the highest dose administered acutely influences indices of whole-body glucose tolerance and insulin sensitivity in healthy subjects.     

Application of Differential Scanning Calorimetry to Starch Gelatinization. III. Effect of Sucrose and Sodium Chloride

The influence of sucrose and salt on the gelatinization endotherm of wheat starch was examined using differential scanning calorimetry. Sucrose was found to decrease gelatinization energy (– ΔH_G) and to increase peak temperature (T_p) as its concentration was increased. Onset and conclusion temperatures (T₀ and T_c) were not affected by sucrose level. The effect of salt on the endotherm was more complex. A decrease in – ΔH_G occurred as the level of this solute in the aqueous phase was raised to 6% but further increases in salt caused it to rise again. Salt levels up to 9% caused increases in T₀ and T_p. With further rises in solute level, T₀ then decreased and T_p remained relatively constant. T_c rose slowly as salt concentration increased.     

The effect of starch gelatinization and solute concentrations on T g′ of starch model system

The effect of starch gelatinization on glass transitions in a starch/water model system and how the concentrations of added solutes (sucrose and sodium chloride) affect the glass transition temperatures of the gelatinized starch solution was investigated. The starch suspension samples were heat treated in a Differential Scanning Calorimeter (DSC) under different time and temperature regimes to achieve different degrees of gelatinization. The gelatinization characteristics (onset, peak and end temperatures and enthalpy) and the glass transition values of a potato starch were determined using the DSC. The results showed that the starch concentrations had no effect on gelatinization characteristics and the T_g′ of the gelatinized potato starch but had clearly increased their ΔC_p in the T_g′ region. Annealing at a temperature slightly below the T_g′ of −5 °C, led to maximal freeze‐concentration in the total/partial gelatinized starch and a higher T_g′ value at about −3 °C was obtained. The T_g′ values of the totally gelatinized starch samples were slightly lower than those of partially gelatinized samples. The T_g′ of the gelatinized starch decreased with increasing concentrations of sucrose or sodium chloride. Sodium chloride had a stronger depressing effect on T_g′ than sucrose. © 2000 Society of Chemical Industry     

Quantitative Analyses of Major Carotenoid Fatty Acid Esters in Fruits by Liquid Chromatography: Persimmon and Papaya

A procedure for the quantitative analyses of major carotenoids and carotenoid esters in persimmons and papayas using column and liquid chromatography is described. The carotenoids and carotenoid esters were first separated by column chromatography on alumina into three fractions by elution with petroleum ether-benzene (80:20), benzene and methanol. The column fractions were further separated by reversed phase liquid chromatography and characterized. The total carotenoid contents in persimmon and papaya calculated as beta-carotene equivalents were 43 and 25 μg/g, respectively. The major carotenoids in persimmon were beta-cryptoxanthin, zeaxanthin, beta-carotene, lycopene and antheraxanthin and the major carotenoids in papaya were beta-cryptoxanthin, cryptoxanthin 5,6-epoxidc, beta-carotene and antherxanthin. The xanthophylls were acylated with C₈ to C₁₆ saturated fatty acids.     

Influence of harvest date on inulin chain length distribution and sugar profile for six chicory (Cichorium intybus L) cultivars

The influence of harvest date on inulin chain length distribution, as well as on the profile of glucose, fructose and sucrose of six different chicory cultivars previously not grown in the northern part of Europe was investigated. Inulin was extracted from both air- and freeze-dried chicory roots and analysed by means of high-performance anion-exchange chromatography with pulsed amperometric detection. Glucose, fructose and sucrose profiles were calculated relative to the total content of these sugars and inulin. The highest weight average degree of polymerization ( DP _w) for inulin was detected for the cultivars Bergues and Tilda ( DP _w 17.6). The longest average inulin chains for all cultivars were found when harvesting chicory during mid and late October, and a significant decrease in DP _w was observed for all cultivars in November in connection with the weather turning colder. Concomitantly, sucrose levels increased significantly. Glucose and fructose levels were found to decrease until mid October and thereafter to increase slightly. © 1999 Society of Chemical Industry     

Resolution of racemic δ-lactone flavors on Chiralcel OB by packed column super critical fluid chromatography

Six racemic δ-lactone (C₇–C₁₂) flavors were successfully resolved in less than 14 min each by packed column super critical CO₂ fluid chromatography (pSFC). Baseline resolution was achieved for δ-C₇–δ-C_10. Chiralcel OB column and modifier isopropanol were selected. The chromatographic conditions including column temperature, column pressure, content of isopropanol in mobile phase and flow rate of mobile phase were optimized while their influences on capacity factor (k), enantioselectivity factor (α) and resolution factor (R _s ) were discussed. The present work indicated that preparative resolution of the δ-lactone racemates by the pSFC method was potential.     

Effect of Solute Type on Sorbate Resistance in Zygosaccharomyces rouxii

The effect of sorbate on the growth of Zygosaccharomyces rouxii was evaluated at reduced a_w using sucrose, glucose and polyethylene glycol (PEG). Sorbate-adapted and unadapted cells were grown aerobically at pH 5.0 in media adjusted to 0.92 a_w by addition of the solutes. Sorbate resistance by unadapted cells increased in the order of glucose < PEG < sucrose. Solute type had little effect on sorbate resistance by sorbate-adapted cells in media containing glucose and sucrose. The combination of PEG and 400 μg/mL sorbate was less inhibitory to sorbate-adapted cells than PEG with 0 μg/mL and 800 μ-g/mL of sorbate.     

Metabolic response of soy pinitol on lipid‐lowering,antioxidant and hepatoprotective action in hamsters fed‐high fat and high cholesterol diet

This study was performed to investigate the lipid‐lowering, antioxidant, and hepato‐protective effects of pinitol in dose‐dependent manners in hamsters fed‐high fat and high cholesterol (HFHC) diet. Pinitol supplementation (0.05%, P‐I and 0.1% pinitol, P‐II) with an HFHC diet (10% coconut oil plus 0.2% cholesterol) for 10 wks significantly lowered the white adipose tissue weights, hepatic lipid droplets, plasma glucose, total‐cholesterol, nonHDL‐cholesterol, total‐cholesterol/HDL‐cholesterol ratio, and hepatic lipid levels. Whereas it significantly increased the brown adipose tissue weight, plasma HDL‐cholesterol, apolipoprotein A‐I (apo A‐I) concentrations, paraoxonase (PON) activity, and/or mRNA expression, compared to the HFHC control group. Plasma insulin and adiponectin levels were significantly lower and higher, respectively, in both P‐I and P‐II groups than the HFHC control group. Dietary pinitol significantly inhibited hepatic HMG‐CoA reductase, acyl‐CoA:cholesterol acyltransferase (ACAT), and cytochrome P4502E1 (CYP2E1) activities without altering their mRNA expressions compared to the control group. Pinitol significantly elevated the hepatic antioxidant enzyme activities, whereas it also significantly reduced the hepatic lipid peroxide and H₂O₂ production. Accordingly, these results indicate that both 0.05 and 0.1% pinitol supplementation may improve the lipid and antioxidant metabolism in HFHC diet‐fed hamsters. In particular, pinitol supplementation was very effective on the elevation of antiatherogenic factors, including plasma HDL‐cholesterol, apo A‐I, adiponectin, and PON.     

Sucrose accumulation and osmotic potentials in sugar beet at increasing levels of potassium nutrition

In a pot experiment sugar beet Beta vulgaris L. ssp. vulgaris, cv. Kawetina, was grown on alluvial soil (21 mg exchangeable K 100 g^?1) containing 0 (K₁), 20 (K₂), 40 (K₃) and 60mg fertiliser K 100 g^?1 soil (K₄). The plants were sown on 15 March 1983 and harvested on 23 June, 14 July and 30 August 1983. At final harvest root dry weight/plant had reached 269 g in K₁ and between 304 and 310 g in K₂-K₄. Sucrose values were 15% (K₁) and 17.3–17.7% of root fresh weight (K₂-K₄) respectively. The osmotic potential of the storage root decreased with increasing K nutrition and time. At final harvest ψ, was between ?1.83 (K₁) and ?2.26 MPa (K₄), 75–79% thereof being contributed by sucrose. Sucrose concentrations in press sap increased from 340–400 mM on 23 June to 475 (K₁) and 540–570 mM (K₂-K₄) at the end of August. In the same period K concentrations declined from 40–100 to 10–35 mM K⁺. The sucrose, K and Mg concentrations measured in the press sap were lower than those calculated from sucrose, K, Mg and moisture content of the storage root. This indicates that press sap from thawed storage root tissue is not fully representative. Betaine, analysed only at final harvest, significantly increased with increasing K concentrations in the storage root (r=0.83) and a significant linear regression was found between betaine and sucrose accumulation (r=0.57). This is consistent with the role of betaine as a cytosolic osmoticum for sugar beet storage tissue. Other solutes in the cytosol may also contribute to osmoregulation as sucrose accumulates in the vacuoles.     

Optical techniques to determine thermal effects on proteins

Optical rotation (OR) and transmitted light (TL) measurements were conducted on 1%, 2.5% and 5% (w/v) bovine serum albumin (BSA) in 0.01 m phosphate buffer at pH 7 and ionic strength 0.08. Denaturation temperatures (T_d) obtained from OR measurements were consistent with reported differential scanning calorimetry values. Protein concentration did not affect T_d in agreement with most reports. Changes in TL reflecting gel formation and protein aggregation were influenced by BSA concentration. Sugar concentration in the range used in this study (0–5%) did not affect the thermal stability of BSA. The lack of difference in sucrose, trehalose and sorbitol effects on the thermal stability of BSA was consistent with some but not all reports. The optical system used to study protein denaturation had acceptable accuracy (consistency with published T_d values) and precision (coefficient of variation under 3.5%) levels.     

Characterization of the Effect of Solutes on the Water-Binding and Gel Strength Properties of Carrageenan

The water activity of carrageenan gels with incorporated solutes was determined by cryoscopic osmometry. Kappa (k), kappalambda (kλ) and iota (κ) carrageenan were utilized at concentrations of from 0.1 2% solids producing a sol, viscous sol, and gel. The solutes used were sucrose, NaCl, Na₂SO₄, KCl, NH₄Cl and urea at concentrations ranging from 0.05–1.0 kinetic units per kg H₂O. All the solutes were found to give a_w values as measured cryoscopically withhin 0.0005 units of literature values. The water activity of pure carrageenans at 0.1–2% solids was greater than 0.999. Addition of some solutes increased the water binding of the carrageenan-solute-water system as was found by a lower a_w than expected. This interaction effect increased with increasing concentration of solute and carrageenan and was greater for solutes with lower activity coefficients. The interaction effect increased in the following order: Na₂SO₄, NaCl, KCl, and NH₄ Cl. The force required to rupture the gel was measured using the Instron Universal Testing Machine. Solutes were found to influence the gel strength of k and kλ carrageenans, but not ι carrageenan. The solutes increased kλ carrageenan's gel strength in increasing order: urea, sucrose, Na₂SO₄, NaCl, NH₄Cl, and KCl and k carrageenan's gel strength in increasing order: sucrose, Na₂SO₄ and NaCl. There appears to be no simple relationship between gel strength and water-binding when solutes are added to carrageenan.     

HPLC determination of γ‐aminobutyric acid in Chinese rice wine using pre‐column derivatization

γ‐Aminobutyric acid (GABA) is a major functional ingredient in Chinese rice wine. A new HPLC method for determining GABA using pre‐column derivatization with dansyl chloride was developed. The HPLC operating conditions were as follows: a Hypersil ODS2 C₁₈ column; mobile phase, methanol and water (1:1); gradient elution; absorption at 254 nm; flow rate, 1 mL/min; pH 9; and column temperature, 30 °C. Under optimal HPLC conditions, the linear equation was y = 3.5 × 10^?7x ? 0.014. The precision (relative standard deviation, RSD) was 0.54%, the stability (RSD) was 0.21%, the recovery ratio was 97.4% and reproducibility (RSD) was 1.57%. This new method appears to be sensitive, accurate, convenient, steady and relatively fast. The results suggest that the new method is also more reliable. Copyright © 2015 The Institute of Brewing & Distilling     

Hydration properties and proton exchange in aqueous sugar solutions studied by time domain nuclear magnetic resonance

Proton NMR relaxation rates (R₁ and R₂) were measured in aqueous solutions of sucrose, d-glucose and d-fructose with increasing concentration. The measurements were carried out using Bruker PC 20 NMR Process Analyzer. Inversion recovery and CPMG pulse sequences are used for the measurement of relaxation rates. Results show that the values of relaxation rate increase as the concentration of the sugar is increased. The relaxation rate appears to be higher for sucrose solutions as compared to glucose or d-fructose solutions. These results were discussed on the basis of molecular association between sugar and water molecules through hydrogen bonding. The water self diffusion coefficient was measured in these sugar solutions by using pulse field gradient NMR method. As expected, the water self-diffusion coefficient was reduced with increased sugar concentrations. The results of translational mobility exhibited a higher mobility for fructose than glucose or sucrose in aqueous solutions.