Lycopene: Heterogeneous Catalytic E/Z Isomerization and In Vitro Bioaccessibility Assessment Using a Diffusion Model

Highly efficient heterogeneous catalytic E/Z isomerization of lycopene was achieved using an iodine‐doped titanium dioxide (I‐TiO₂) catalyst prepared by sol‐gel method. The effects of reaction temperature and reaction time were investigated in detail. The maximum total Z‐ratio of lycopene exceeded 78% after 2 h of refluxing at 75 °C in ethyl acetate. Moreover, lycopene samples with a series of total Z‐ratios were prepared and the bioaccessibility of these samples was estimated using a diffusion model, the results showed that the bioaccessibility of lycopene markedly increased conforming to a linear regression model with increasing of the total Z‐ratio of lycopene from 3.6% to 78.5%. Furthermore, the specific role of the microstructure and melting point of 3.6% and 78.5% total Z‐ratio of lycopene was also investigated to understand the probable mechanism for the enhanced bioaccessbility of (Z)‐lycopenes.     

Effects of Heat Treatment on the Carotenoid and Tocopherol Composition of Tomato

Abstract: The objective of this study was to determine the influence of thermal processing on the assessment of tocopherols and carotenoids, as well as their isomer formation in tomatoes. The sliced tomatoes were heated in an oven at 100, 130, and 160 °C for 5, 10, and 20 min, then freeze‐dried. Freeze‐dried samples were finely ground and the analysis was performed on lyophilized samples. The average concentrations of total lycopene, lutein, β‐carotene, α‐tocopherol, and γ‐tocopherol in fresh tomatoes (in 100 g dry weight) were 21.2, 1.1, 2.7, 8.0, and 2.5 mg, respectively. Oven baking of tomato at 160 °C for 20 min led to a significant increase in the apparent measurement of lycopene, β‐carotene, and α‐tocopherol content by 75%, 81%, and 32%, respectively. Heating induced isomerization of (all‐E) to various (Z) isomers of lycopene, and we found that the total (Z)‐lycopene proportion in the tomatoes increased with longer heating time. (All‐E)‐lycopene constituted 75.4% in fresh tomatoes and decreased to 52.5% in oven‐baked tomatoes (160 °C, 20 min), while (5Z)‐lycopene increased from 9.4% to 17.9% of total lycopene. However, β‐carotene release and isomerization was less influenced by the heat treatment than that of lycopene. These results suggested that thermal processes might break down cell walls and enhance the release of carotenoids and tocopherols from the matrix, as well as increase isomerization of lycopene and β‐carotene.     

Iron(II)-induced isomerization of (<Emphasis Type="Italic">all</Emphasis>-<Emphasis Type="Italic">E</Emphasis>)-xanthophyll pigments lutein,zeaxanthin, and β cryptoxanthin in acetone

Lutein, zeaxanthin, and β-cryptoxanthin are xanthophyll pigments that own conjugated double bonds; some factors can convert (all-E)-xanthophylls to their (Z)-isomers such as high temperature, illumination, and oxidants. In the present work, the Fe(II)-induced isomerization of (all-E)-lutein, (all-E)-zeaxanthin, and (all-E)-β-cryptoxanthin in acetone were analyzed by HPLC coupled with DAD and APcI-MS. The three (all-E)-xanthophylls were baseline separated and their (Z)-isomers were identified by the chromatographic retention, UV/vis spectra and positive mass spectrometry with reference values reported in the literature. The results showed that Fe(II) exhibited a rapidly isomerization induction of (all-E)-xanthophylls to their (Z)-isomers exceeding a 8/1 mass ratio of Fe(II)/pigments. The (13-Z)-lutein and (13′-Z)-lutein were identified as the major (Z)-isomers of (all-E)-lutein treated with FeSO₄·7H₂O, and (13-Z)-zeaxanthin was identified as the major isomerization product of (all-E)-zeaxanthin. Furthermore, a type of (Z)-β-cryptoxanthin was also detected. Increasing either mass ratio of Fe(II)/pigments or the incubation time of FeSO₄·7H₂O and (all-E)-xanthophylls may affect on the stabilities of (Z)-isomers derived from (all-E)-xanthophylls.     

Effects of genotype and cultivation environment on lycopene content in red‐ripe tomatoes

Lycopene, a natural red pigment found in tomato, is correlated with reduced incidence of some cancers. Forty tomato varieties, including cluster F₁ hybrid tomatoes, round breeding line tomatoes (Lycopersicon esculentum Mill) and cherry tomato types (L esculentum var cerasiforme), grown under greenhouse and field conditions were evaluated for their lycopene content using high‐performance liquid chromatography (HPLC) and spectrophotometry. Lycopene content varied significantly among the tomato varieties, with cherry tomato types having the highest lycopene content. Greenhouse‐grown cluster and round tomatoes contained more lycopene (mean = 30.3 mg kg^?1) than field‐grown tomatoes (mean = 25.2 mg kg^?1), whereas cherry tomato types had a higher lycopene content in field‐grown (mean = 91.9 mg kg^?1) than in greenhouse‐grown (mean = 56.1 mg kg^?1) fruits. HPLC analysis of lycopene isomeric forms revealed a higher content of all‐trans isomers in all tomato genotypes examined. However, the cis isomeric form was exceptionally higher in the field‐ and greenhouse‐grown cherry tomato L esculentum var cerasiforme cv Gardener's Delight, which contained ～9.3 and 9.9 mg kg^?1 cis isomers respectively. Results indicate that genetics and choice of cultivation environment may have a strong influence on tomato lycopene content. Copyright © 2005 Society of Chemical Industry     

Lycopene (Z) – isomers enrichment and separation

(All‐E)‐ Lycopene undergoes geometrical isomerisation into (Z)‐lycopene isomers with thermal treatment. Influence of three isomerisation methods including ethyl acetate reflux, microwave‐assisted reflux and ultrasound/microwave‐assisted reflux, and isolation of (all‐E)‐lycopene from other carotenoids and (Z) lycopene isomers through selective inclusion by deoxycholic acid (3α, 12α dihydroxy‐5βcolan‐24‐oic‐acid, DCA) were investigated. The results showed that microwave and ultrasound/microwave‐assisted reflux were not significantly different at P < 0.05, but both were significantly different (P < 0.05) over refluxing in ethyl acetate, proportion of (Z)‐lycopene isomers reached 54% after refluxing for 5 h. Heterogeneous mixture of isomerised tomato oleoresin containing 54% (Z)‐lycopene isomers and 40% (all‐E)‐lycopene and deoxycholic acid in dichloromethane was incubated at 25 °C for 2 h. Then, the mixture was filtered and from the filtrate 96.6% (Z)‐isomers enriched lycopene was obtained. The processes can be used in the production of enriched (Z)‐lycopene isomers for food supplements and functional food industry as a natural bioactive ingredient.     

In vitro degradation by mixed rumen bacteria of 17 mono‐ and sesquiterpenes typical of winter and spring diets of goats on Basilitica rangelands (southern Italy)

BACKGROUND: Nine monoterpenes (δ‐3‐carene, p‐cymene, limonene, β‐myrcene, (E)‐ and (Z)‐β‐ocimene, α‐phellandrene, α‐terpinene, γ‐terpinene), seven oxygenated monoterpenes (1,8‐cineole, linalool, (E)‐ and (Z)‐linalool oxide, 4‐terpinenol, α‐terpineol, α‐terpinolene) and one sesquiterpene (β‐cedrene) were investigated for their degradability in the rumen microbial ecosystem. These molecules were identified as dominant terpenes in the winter and spring diets of milking goats in Basilicata (southern Italy). RESULTS: All terpenes were tested at 3.33 µL L^?1 for 24 h using in vitro incubation with mixed rumen bacteria from dairy goats. Oxygen‐containing compounds were those recovered at the highest levels (89% of (E)‐linalool oxide, 93% of (Z)‐linalool oxide, 91% of 1,8‐cineole, 82% of terpineol and 72% of 4‐terpinenol), except linalool. The linear alkenes β‐myrcene and β‐ocimene almost completely disappeared. Results were more variable among cyclic alkenes, with recovery rates ranging from 50% in the case of limonene to less than 1% for α‐phellandrene. 17% of the only sesquiterpene of the group, β‐cedrene, was recovered. CONCLUSION: Recovery rates differed markedly among terpenes, partly in relation to the presence of oxygen and rings in the molecules. These observations should contribute to a better understanding of the changes in composition between the diet and milk terpenes. Copyright © 2008 Society of Chemical Industry     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

Effect of dietary lipid sources on odour‐active compounds in muscle of turbot (Psetta maxima)

Odour‐active compounds in muscle of turbot (Psetta maxima) fed experimental diets containing fish oil (FO), soybean oil (SO) or linseed oil (LO) were investigated by a gas chromatography/olfactometry technique. Thirty‐one areas associated with odours were detected in muscle extracts. Among the compounds responsible for these odours, 23 were formed by oxidation of unsaturated fatty acids. Independently of diet, (E)‐2‐penten‐1‐ol and (E)‐3‐hexen‐1‐ol contribute strongly to the odour of turbot. (E,Z)‐2,6‐Nonadienal, (E)‐2‐pentenal and (E,E)‐1,3‐(Z)‐5‐octatriene seem to contribute strongly to the odour of turbot fed diets containing high levels of n‐3 PUFA (FO and LO groups). Hexanal and decanal show a high detection frequency in turbot fed diets containing vegetable oils. Odorous compounds which are not formed by lipid oxidation (methional, 1‐acetyl pyrazine, 4‐ethyl benzaldehyde and 2‐acetyl‐2‐thiazoline) were not affected by dietary lipid sources. © 2001 Society of Chemical Industry     

Effects of postharvest UV‐C treatment on carotenoids and phenolic compounds of vine‐ripe tomatoes

Light red tomatoes were exposed to different doses of ultraviolet C (UV‐C) irradiation (1.0, 3.0 and 12.2 kJ m^?2). After treatment, the tomatoes were stored for 2 days at room temperature, and then analysed to determine the effect of irradiation on the main antioxidants, carotenoids and phenolic compounds and the results compared with the control samples. The lycopene content was found to have increased by 14% with respect to the control samples, while β‐carotene decreased. Cis‐isomers from lycopene also increased when the tomatoes were exposed to irradiation for more than 3 h. UV‐C irradiation also had a positive effect on total phenolic compounds; however, the same effect was not observed in the individually analysed phenolic compounds. While chlorogenic and ferulic acids increased in content, naringenin and rutin contents decreased. These results suggest that UV‐C irradiation of tomatoes could improve the beneficial effect of red tomatoes for human health by increasing the levels of certain bioactive compounds; it could also be used to obtain higher content of bioavailability components, such as cis‐isomers from lycopene.     

Purification,properties and heat inactivation of pectin methylesterase from apple (cv Golden Delicious)

Pectin methylesterase from apple (cv Golden Delicious) was extracted and purified by affinity chromatography on a CNBr‐Sepharose®‐PMEI column. A single pectin methylesterase peak was observed. Isoelectric points were higher than 9. Kinetic parameters of the enzyme were determined as K_m = 0.098 mg ml⁻¹ and V_max = 3.86 µmol min⁻¹ ml⁻¹ of enzyme. The optimum pH of the enzyme was above 7.5 and its optimum temperature was 63 °C. The purified PME required the presence of NaCl for optimum activity, and the sodium chloride optimum concentration increased with decreasing pH (from 0.13 M at pH 7 to 0.75 M at pH 4). The heat stability of purified PME was investigated without and with glycerol (50%), and thermal resistance parameters (D and Z values) were calculated showing that glycerol improved the heat resistance of apple PME. © 2000 Society of Chemical Industry     

Optimisation of microwave‐assisted extraction of Gac oil at different hydraulic pressure,microwave and steaming conditions

The study aimed to optimise Gac (Momordica cochinchinensis Spreng) oil extraction conditions, including microwave time, steaming time and hydraulic pressure, for maximising extraction efficiency (EE), and β‐carotene and lycopene contents, using response surface methodology. Results indicated that the data were adequately fitted into three second‐order polynomial models for EE, β‐carotene and lycopene with R² values of 0.93, 0.85 and 0.86, respectively. It was predicted that the optimum extraction conditions within the experimental ranges would be the microwaving time of 62 min, steaming time of 22 min and hydraulic pressure of 175 kg cm^?2. Under such parameters, the maximum EE of 86%, β‐carotene content of 186 mg per 100 mL oil and lycopene content of 518 mg per 100 mL oil were achieved as predicted.     

Optimisation of tripalmitin‐rich fractionation from palm stearin by response surface methodology

BACKGROUND: Solvent fractionation is effective in improving separation at low temperature, resulting in higher yield and purity of the final product. Tripalmitin (PPP) is an important substrate for the synthesis of human milk fat substitute (HMFS). In this study a fraction rich in PPP was separated from palm stearin by solvent fractionation. RESULTS: The PPP‐rich fraction was concentrated from palm stearin by acetone fractionation. Response surface methodology (RSM) was employed to optimise PPP purity (Y₁, %) and PPP content (Y₂, g kg^?1 palm stearin) with the independent variables fractionation temperature (X₁, 25, 30 and 35 °C) and weight ratio of palm stearin to acetone (X₂, 1:3, 1:6 and 1:9). The predictive models for PPP purity and PPP content of the solid fraction were adequate and reproducible, with no significant lack of fit and satisfactory levels of R². PPP purity showed a positive correlation with temperature and acetone ratio, whereas PPP content exhibited a negative correlation. The optimised fractionation condition for a targeted PPP‐rich fraction with > 92% PPP purity and > 225 g kg^?1 PPP content from palm stearin was predicted. CONCLUSION: The RSM model for optimising PPP purity and PPP content in the PPP‐rich fraction from palm stearin by acetone fractionation was valid. The scaled‐up PPP‐rich fraction obtained can be used as a substrate for the synthesis of 1,3‐dioleoyl‐2‐palmitoylglycerol, which is a main component of HMFS in infant formulas. Copyright © 2010 Society of Chemical Industry     

Improving 2‐phenylethanol and 6‐pentyl‐α‐pyrone production with fungi by microparticle‐enhanced cultivation (MPEC)

Trichoderma atroviride IMI 206040 synthesizes the coconut lactone 6‐pentyl‐α‐pyrone (6‐PAP) de novo and Aspergillus niger DSM 821 produces the rose‐like flavour compound 2‐phenylethanol (2‐PE) from the precursor l ‐phenylalanine. Here, microparticles of different chemical composition and nominal particle diameter in the range 5–250 µm were added to shake‐flask cultures of both fungi to investigate the particles' effect on product formation. Maximum 2‐PE concentration increased by a factor of 1.3 to 1430 mg/l with the addition of 2% w/v talc (40 µm diameter). Maximum 6‐PAP concentration increased by a factor of 2 to 40 mg/l with the addition of 2% w/v iron (II, III) oxide. The influence of ions leaching out of the particles was investigated by cultivating the fungi in leached particle medium. For the first time, the positive effect of the microparticle‐enhanced cultivation (MPEC) technique on the microbial production of volatile metabolites, here flavour compounds from submerged fungal cultures, is demonstrated. The effect is strain‐ and particle‐specific. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimization of Homogenization–Evaporation Process for Lycopene Nanoemulsion Production and Its Beverage Applications

Lycopene is a natural antioxidant which has several health benefits. Undesirable oxidation of lycopene compromises its health benefits and also affects the sensory quality of food products containing lycopene. Health benefits associated with lycopene in food preparations can be enhanced by preventing its degradation by incorporating it into the oil phase of an oil‐in‐water nanoemulsion. In this study, lycopene nanoemulsions were prepared from a low‐concentration lycopene extract using an emulsification–evaporation technique. The effects of the concentrations of the lycopene extract (0.015 to 0.085 mg/mL) and emulsifier (0.3 to 0.7 mg/mL), and the number of homogenization cycles (2 to 4) on the droplet size, emulsification efficiency (EE), and nanoemulsion stability were investigated and optimized by statistical analysis using a Box‐Behnken design. Regression analysis was used to determine the 2nd‐order polynomial model relationship of independent and dependent variables, with multiple regression coefficients (R²) of 0.924, 0.933, and 0.872, for the droplet size, EE, and nanoemulsion stability, respectively. Analysis of variance showed that the lycopene extract concentration has the most significant effect on all the response variables. Response surface methodology predicted that a formulation containing 0.085 mg/mL of lycopene extract and 0.7 mg/mL of emulsifier, subjected to 3 homogenization cycles, is optimal for achieving the smallest droplet size, greatest emulsion stability, and acceptable EE. The observed responses were in agreement with the predicted values of the optimized formulation. This study provided important information about the statistical design of lycopene nanoemulsion preparation.     

Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g^?1) than in the second (2.24 mg g^?1) or first crop season (1.79 mg g^?1). The amount of anthocyanins contained in the stem was high (1.61 mg g^?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g^?1, 0.52 mg g^?1, 0.40 mg g^?1, 0.22 mg g^?1, 0.14 mg g^?1, and 0.11 mg g^?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry     

Carotenoids,but Not Vitamin A,Improve Iron Uptake and Ferritin Synthesis by Caco‐2 Cells from Ferrous Fumarate and NaFe‐EDTA

Due to the high prevalence of iron and vitamin A deficiencies and to the controversy about the role of vitamin A and carotenoids in iron absorption, the objectives of this study were to evaluate the following: (1) the effect of a molar excess of vitamin A as well as the role of tannic acid on iron uptake by Caco‐2 cells; (2) iron uptake and ferritin synthesis in presence of carotenoids without pro‐vitamin A activity: lycopene, lutein, and zeaxantin; and (3) iron uptake and ferritin synthesis from ferrous fumarate and NaFe‐EDTA. Cells were incubated 1 h at 37 °C in PBS pH 5.5, containing ⁵⁹Fe and different iron compounds. Vitamin A, ferrous fumarate, β‐carotene, lycopene, lutein, zeaxantin, and tannic acid were added to evaluate uptake. Ferritin synthesis was measured 24 h after uptake experiments. Vitamin A had no effect on iron uptake by Caco‐2 cells, and was significantly lower from NaFe‐EDTA than from ferrous fumarate (15.2 ± 2.5 compared with 52.5 ± 8.3 pmol Fe/mg cell protein, respectively). Carotenoids increase uptake up to 50% from fumarate and up to 300% from NaFe‐EDTA, since absorption from this compound is low when administered alone. We conclude the following: (1) There was no effect of vitamin A on iron uptake and ferritin synthesis by Caco‐2cells. (2) Carotenoids significantly increased iron uptake from ferrous fumarate and NaFe‐EDTA, and were capable of partially overcoming the inhibition produced by tannic acid. (3) Iron uptake by Caco‐2 cell from NaFe‐EDTA was significantly lower compared to other iron compounds, although carotenoids increased and tannic acid inhibited iron uptake comparably to ferrous fumarate.     

Evaluation of free radical scavenging of dietary carotenoids by the stable radical 2,2‐diphenyl‐1‐picrylhydrazyl

In order to avoid the interference of compounds with a chromophoric system when the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^·) method is used, a new measure of the decrease in absorbance at 580 nm was performed (correlation coefficient between absorbance and DPPH^· concentration, 0.9979; p < 0.01). The antioxidant effectiveness of dietary carotenes and xanthophylls towards the stable free radical DPPH^· was measured. The antioxidant activity expressed as the amount of antioxidant able to reduce the initial DPPH^· concentration to 50% (EC₅₀), given in terms of moles of antioxidant per mole of DPPH^·, ranged from 0.16 ± 0.01 (lycopene) to 3.29 ± 0.31 (lutein). The parameter antiradical efficiency (AE), which involves the potency (1/EC₅₀) and the time taken to reach the steady state at EC₅₀ (T_EC50), was calculated to discriminate carotenoids with no significant difference between their EC₅₀. Comparison of the structures of the carotenoids tested revealed that the scavenging ability towards DPPH^· was increased by the length of the effective conjugated double‐bond system and was modulated by the addition of chemical groups on the terminal rings (xanthophylls). © 2000 Society of Chemical Industry     

Glutaminase‐induced deamidation and hydrolysis of casein and metal‐chelating or ACE‐inhibitory activity of the hydrolysates in vitro

Glutaminase (EC 3.5.1.2) was applied in this work to induce deamidation and hydrolysis of casein. Some reaction conditions based on casein deamidation were studied. Three casein hydrolysates with degree of deamidation of 2.8%, 5.8% and 8.5%, or degree of hydrolysis of 2.5%, 3.4% and 4.9%, respectively, were prepared at casein concentration 5% (w/v), glutaminase addition level 400 U kg^?1 casein, reaction temperature 37 °C and reaction times 6, 12 and 24 h, respectively. Evaluation results showed that when iron (II) was added at 60 μm , iron (II)‐chelating powers of three hydrolysates were 41.1, 45.4 and 55.3%, while that of original casein and EDTA were 36.1 and 13.6%. Calcium (II)‐chelating power of three hydrolysates was 1.23, 1.41 and 1.49 mmol g^?1 casein, whereas that of original casein was 1.05 mmol g^?1 casein. Three hydrolysates also had ACE‐inhibitory activity in vitro, with IC₅₀ values from 0.75 to 2.34 mg mL^?1.     

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     

Multiple forms of β‐galactosidase from mango (Mangifera indica L Alphonso) fruit pulp

Mango (Mangifera indica L cv Alphonso) was found to contain three isoforms (I, II and III) of β‐galactosidase which, upon purification on Sephadex G‐200, had relative abundances of 44, 38 and 18%, respectively. The total specific activity increased from 20 to 727 µmol l^?1 upon purification, representing a ～36‐fold increase with a recovery of 0.28 U U^?1. The optimal pH for activity and stability were in the ranges 3.6–4.3 and 4–6.2, respectively. The optimal temperature for β‐galactosidase activity was between 42 and 47 °C with T_m in the range 45–51 °C. The K_m for pNP‐β‐galactopyranoside was 0.98, 1.11 and 0.95 mM , and V_max was 0.56, 0.53 and 0.35 µmol pNP min^?1, respectively for isoforms I, II and III. Hg²⁺ caused strong inhibition, whereas galacturonic acid, galactose, xylose, fucose and mannose slightly inhibited the activity of β‐galactosidase isoforms. The apparent molecular weights by GPC were 78, 58 and 91 kDa for isoforms I, II and III, respectively. The ability of these isoforms to degrade the endogenous substrate (arabinogalactan) possibly suggests a role in pectin dissolution during tissue softening/fruit ripening. Copyright © 2004 Society of Chemical Industry