A simple preparative method for isolation and purification of polysaccharides from mulberry (Morus alba L.) leaves

An effective method for preparative extraction and purification of the polysaccharides from mulberry leaves was studied. Orthogonal experiment was carried out to get the optimal conditions (T = 70 °C, pH = 6, t = 60 min, D = 0.4 g g^?1 material) of activated carbon decolorisation. The staged, isocratic and multiple ethanol precipitation procedures were also investigated. Through the activated carbon decolorisation and 20% ethanol precipitation procedure, the polysaccharides yield reached 2.91%, and the content of neutral sugar and uronic acid were improved to 21.87% and 57.43% respectively. This process was superior to the macroporous resin adsorption and gel permeation chromatography (GPC) methods. The structure analysis indicated that the purified mulberry leaves polysaccharide (MLP) was composed of Man, GalA and Rha in the ratio of 1.0:7.2:20.0. The molecular weight measured using GPC was approximately 557 062 D. The IR and ¹H NMR spectra indicated that the MLP was mainly pectin, which was classified as high‐methoxyl pectin.     

Rheological,thermal and sensory properties of whey protein concentrate/pectin‐fortified mashed potatoes made from dehydrated flakes

The effect of different amounts of whey protein concentrate (50–150 g kg^?1), low and high methoxyl pectin (5–15 g kg^?1) on the rheological, thermal, structural properties and sensory quality of mashed potatoes prepared from dried mashed potatoes flakes was investigated. The response surface technique was used to analyse the effects of whey protein concentrate and pectin simultaneously on the consistency index, flow behaviour index, apparent viscosity and Casson plastic viscosity. Both whey protein concentrate and pectin decreased the consistency of the mashed potatoes weakening its structure in all concentrations assayed. Results suggest that whey protein concentrate interacts with high methoxyl pectin through non‐covalent interactions. Based on the sensory evaluation results, up to 100 g kg^?1 whey protein concentrate with 15 g kg^?1 of low methoxyl pectin and 15 g kg^?1 of high methxyl pectin could be incorporated to dried mashed potatoes flakes without losing significantly the sensory quality of the product.     

Polyphenolic composition,antioxidant and antiproliferative effects of wild and cultivated blackberries (Rubus fruticosus L.) pomace

The content of total polyphenolics, antioxidative capacity and antiproliferative activity were tested in wild and cultivated blackberry pomace. Wild blackberry pomace extract Tw2 showed the highest following contents: total polyphenolics (50.16 mg GAE g⁻¹ dw), flavonoids (7.73 mg Qc g⁻¹ dw), flavonols (6.63 mg Qc g⁻¹ dw) and total monomeric anthocyanins (13.40 mg Cy g⁻¹). Tw2 extract significantly inhibited free radicals: IC₅₀^DPPH = 127.76 μg mL⁻¹, IC₅₀^ABTS = 26.53 μg mL⁻¹ and IC₅₀ ^{˙ OH} = 168.62 μg mL⁻¹, and the growth of breast adenocarcinoma IC₅₀^MCF7 = 306.68 μg mL⁻¹ and cervix epitheloid carcinoma cell lines IC₅₀^HeLa = 315.49 μg mL⁻¹. Wild blackberry varieties had higher extraction yields, higher total polyphenolic contents and possessed stronger biological effects compared to cultivated blackberries (P < 0.05). All blackberry extracts showed high biological potential that could be attributed to high total polyphenols and flavonoids content and could be utilised as value-added functional food.     

Effect of storage period on provitamin-A carotenoids retention in biofortified maize hybrids

Vitamin A-rich maize hybrids provide sustainable solutions to malnutrition. However, significant loss of carotenoids during storage reduces its efficacy. Grains of nine sub-tropically adapted crtRB1-based biofortified hybrids along with six normal hybrids were stored under conventional storage for five months. PVAC (β-carotene and β-cryptoxanthin) among crtRB1-based hybrids degraded from initial level of 18.77 to 3.24 µg g⁻¹, while NPVAC (lutein and zeaxanthin) reduced to 10.79 µg g⁻¹ from 19.00 µg g⁻¹ during storage. Among PVAC, β-cryptoxanthin (21.8%) possessed more stability than β-carotene (16.4%). For NPVAC, lutein (61.2%) showed the highest retention than zeaxanthin (50.4%). Majority of the PVAC loss occurred within first three months of storage. Retention for PVAC among crtRB1-based hybrids varied from 14% to 23% indicating the role of favourable genetic factors. APQH1, APQH7 and APH2 were the promising hybrids with higher retention (>20%) of PVAC. This is the first report on identification of provitamin A-rich crtRB1-based biofortified maize hybrids with higher retention during sub-tropical storage.     

Dietary fibre extracted from different types of whole grains and beans: a comparative study

Dietary fibre (DF) from different whole grains and beans (quinoa, buckwheat, highland barley, pea and mung bean) was extracted by enzymatic action. The components, crystallinity and properties were comparatively studied. Furthermore, we evaluated correlations between DF components and their crystallinity, thermal, physicochemical and functional properties. Results showed quinoa DF had highest polyphenol (25.58 mg GAE per 100 g), pectin (4.68%) and cellulose (52.34%) contents, crystallinity value (CV, 30.24%), ΔH (185.53 J g⁻¹), water-holding capacity (WHC, 5.35 g g⁻¹), α-amylase activity inhibition ratio (α-AAIR, 13.34%) and glucose absorption capacity (GAC), but lowest protein content (9.78%) and T_p (163.05 °C). Mung bean DF had highest lignin content (33.56%), fat adsorption capacity (4.73 g g⁻¹), and T_p (176.25 °C), but lowest CV (15.26%) and ΔH (132.15 J g⁻¹). Correlation analysis showed cellulose content had positive linear correlations with CV, ΔH, WHC, α-AAIR and GAC, but a negative correlation with T_p. The structure and properties of DF are largely attributed to cellulose content.     

Colour and flavour of potato protein preparations,depending on the antioxidants and coagulants used

The colour and profile of the aromatic compounds of potato juice (PJ) protein preparations were investigated following various process modifications. Several antioxidants (sodium bisulphate, tartaric acid, ascorbic acid), acidulants (tartaric, ascorbic and hydrochloric acids) and chelating agents (chloride, lactate and calcium hydrogen phosphate salts) used for pectin removal during the coagulation of the PJ proteins were evaluated. The combination of sodium bisulphate or ascorbic acid as antioxidants, with calcium chloride or lactate, and ascorbic acid as the protein coagulant, increased the brightness of the protein preparations. Forty-one aromatic compounds, including aldehydes, alcohols and alkanes, were identified. The total concentration of volatiles ranged 59–105 μg g⁻¹. The ascorbate variant contained the lowest n-hexanal concentration. Different treatments did not impact significantly on the 2-methyl-propanal and 2-methyl-butanal concentrations. Interestingly, 2-pentylfuran production was dramatically reduced (16.48 μg g⁻¹) in the lactic variant in comparison to 40.52 μg g⁻¹ with CaHPO₄ addition.     

Oxalic extraction of high methoxyl pectin and its application as a stabiliser

The objective of this work was to extract high methoxyl (HM) pectin with oxalic acid, characterise its physicochemical properties and evaluate its dispersion stability in acidified milk drink (AMD). HPSEC–MALLS analysis revealed that the obtained HM pectin was high in molecular weight (522.4 kDa). The ζ-potential of the obtained HM pectin in aqueous solution at pH 4.0 was −31.5 mV. The AFM images proved that the obtained HM pectin contained several long linear molecules. The apparent diameter of AMD stabilised by the obtained HM pectin was 636 nm at the concentration of 3.0‰. The stability analysis of AMD and the microscopic observation with confocal laser scanning microscopy (CLSM) proved that the obtained HM pectin was a prominent stabiliser in AMD.     

Microstructure characteristics of tea seed dietary fibre and its effect on cholesterol,glucose and nitrite ion adsorption capacities in vitro: a comparison study among different modifications

The effects of xylanase–cellulase hydrolysis, ultrasonic modification and enzymatic-ultrasonic treatment on the physicochemical properties, morphological structures and adsorption capacities in vitro of purified fibre (PF) from tea seed were determined. The results showed the ultrasonically treated fibre (UTF) had a higher water-holding capacity (60.15 g g⁻¹), oil-binding capacity (30.42 g g⁻¹), swelling capacity (29.93 mL g⁻¹), emulsification activity (381.36 m² g⁻¹) and emulsification stability (20.20) than PF, enzymatically hydrolysed fibre (EHF) and enzymatic-ultrasonic treated fibre (EUF). The structures of PF, UTF, EHF and EUF were characterised by scanning electron microscope, Laser particle size analyzer, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectra. Furthermore, compared with PF, the adsorption capacity of UTF, EHF and EUF for cholesterol, glucose and nitrite ions during simulative gastrointestinal tract was improved to different degrees. This study can provide guidance for the comprehensive utilisation of byproduct of tea seed and designing novel functional dietary fibre.     

Impact of lecithin incorporation on gel properties of bigeye snapper (Priacanthus tayenus) surimi

Gelling characteristics of bigeye snapper (Priacanthus tayenus) surimi functionalised by lecithin at different concentrations were investigated. Lecithin at ≤1 g 100 g⁻¹ had no impact on breaking force and deformation (P > 0.05). Expressible drip tended to decrease with increasing lecithin level up to 1 g 100 g⁻¹. Lecithin at 1–3 g 100 g⁻¹ improved the whiteness (P < 0.05). Jointed clusters were formed in the gel microstructure with 1 g 100 g⁻¹ lecithin. Gel without and with 1 g 100 g⁻¹ lecithin had the same texture profile and likeness scores (texture, odour and flavour) (P > 0.05). Peroxide value, TBARS content and rancid odour score of gels were changed considerably during refrigerated storage (4 °C/polyethylene bag) for 15 days but lower values of all indices were noticeable in gel with lecithin. Therefore, lecithin at 1 g 100 g⁻¹ was the optimum concentration for stabilising the texture, improving the water holding capacity, whitening the colour and retarding the lipid oxidation of bigeye snapper surimi gel.     

An explorative study on the cell wall polysaccharides in the pulp and peel of dragon fruits (Hylocereus spp.)

The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.     

Extrusion improved the physical and chemical properties of dietary fibre from bamboo shoot by-products

Bamboo shoot by-products are regarded as waste and environmental pollutant. This study aimed to improve the functional properties of dietary fibre from bamboo shoot by-products. After CO₂ extrusion, the particle size of CO₂-extruded bamboo fibre was 17.6% lower than that of the control, and its specific surface area was 2.85 times that of the control. The soluble dietary fibre content was significantly increased from 5.64 g/100 g to 11.05 g/100 g (P < 0.05), and the capacities for water holding, swelling and oil holding were remarkably improved. The cholesterol adsorption of CO₂-extruded bamboo fibre was increased from 96.54 μg g⁻¹ to 174.65 μg g⁻¹ (pH 7.0), and its nitrite ion adsorption capacity was increased from 503.33 μg g⁻¹ to 657.27 μg g⁻¹ (pH 2.0). In summary, the structural changes of bamboo fibre such as internal porosity, surface roughening and low crystallinity indicated that its functional properties were improved after CO₂ extrusion.     

Hydration of casein micelles and caseinates: Implications for casein micelle structure

By studying the hydration of casein micelles using a variety of techniques, a distinction could be made between water that appeared bound by the protein (∼0.5 g g⁻¹ protein), water associated with the κ-casein brush (∼1.0 g g⁻¹ protein) and water entrapped in the casein micelles (∼1.8 g g⁻¹ protein), yielding a total micellar hydration of ∼3.3 g g⁻¹ protein, in line with casein micelle voluminosity derived from intrinsic viscosity measurements. For caseinate particles, however, the main contributor to intrinsic viscosity was not protein hydration but the non-spherical particle shape. These non-spherical particles in caseinate are likely to be naturally present as primary casein particles (PCP) in casein micelles. PCP could be used to build casein micelles by controlled introduction of micellar salts. Based on the findings of this study, casein micelles could be described as a porous network of non-spherical PCP linked by calcium phosphate nanoclusters.     

Processing and Quality Evaluation of a Low-Calorie Christophene Jam (Sechium edule (Jacq.) Swartz

ABSTRACT: Effects of high methoxyl pectin (2% HM) and low methoxyl pectin (1.0,2.0% LM) and carrageenan (0.03, 0.06, 0.09%) on gel set and texture were investigated in the production of a low-calorie (13g /1tbsp jam of < 10 calories) christophene ( Sechium edule (Jacq.) jam. Inclusion of aspartame, saccharin with aspartame, and sucralose in jam provided sweetness and bulkiness while saccharin contributed to sweetness. Pectin had no effect ( P > 0.05) on texture but provided gel set ( P < 0.05). A jam of 12°Brix, pH 3.62, 2% HM pectin, 0.03% carrageenan, with 1.9% sucralose was "liked moderately" to "very much". Based on ranking, sucralose was most preferred ( P < 0.05) over other sweeteners. Sensory texture of jam improved on storage at 7 °C but with loss ( P < 0.05) of total soluble solids and significant fading ( P < 0.05) of color by day 35.     

Evaluation of various Bacillus coagulans isolates for the production of high purity L-lactic acid using defatted rice bran hydrolysates

Defatted rice bran (DRB) constitutes an abundant by-product stream, generated during rice milling and subsequent bran oil extraction. Enzymatic hydrolysis of starch and protein content in DRB was optimised in terms of solid loading. Among the four solid loadings evaluated (10%, 15%, 20% and 25%), the hydrolysate derived from 20% solids resulted in the highest concentration of glucose (82.3 g L⁻¹) and free amino nitrogen (234.8 mg L⁻¹). The fermentability of the hydrolysate was evaluated via screening of sixteen isolates. All the strains were able to grow and produce high purity L-lactic acid, utilising the DRB as sole carbon and nutrient source. Among the studied strains, the Bacillus coagulans A107 isolate presented the most promising results in terms of final lactic acid concentration (75.9 g L⁻¹), yield (0.90 g g⁻¹) and productivity (2.7 g L⁻¹ h⁻¹). The results of this study indicate that DRB could be employed as an inexpensive, alternative substrate for L-lactic acid production.     

Improved function of bamboo shoot fibre by high-speed shear dispersing combined with enzyme treatment

With the increase in global welfare, metabolic syndrome-related diseases seriously disrupt our quality of life. Balanced diet with low calories, low glycaemic index, and high dietary fibre such as bamboo shoot fibre is needed. Functional properties of dietary fibre can be improved by processing methods. Therefore, we compared the effect of three processing methods (high-speed shear dispersing, enzyme treatment and combined treatment) on the characteristics and functions of bamboo shoot fibres. Combined treatment resulted in high SDF content (10.15%), adsorption capacity of glucose (4.45–18.18 mmol g⁻¹), nitrite ion (505.49 μg g⁻¹ [pH 2.0]), and cholesterol (333.72 μg g⁻¹ [pH 2.0]). FTIR revealed that hydroxyl groups, sugar methylene and benzene rings of aromatic compounds existed in the treated bamboo shoots. The particle size (D₅₀) decreased from 383.90 to 30.65 μm. Honeycomb-like structure was also observed through SEM. Thus, proper processing of bamboo shoot fibres can improve their functions as food ingredients.     

Comparison of nutritional value and microbiological status of new imported fish species on the German market

Proximate composition, fatty acid profile, other nutritional values and spoilage indicators were examined in the muscle meat of five species: barramundi (Lates calcarifer) from various origins, tilapia (Oreochromis spp.) of different qualities, cobia (Rachycentron canadum) and leather jacket (Aluterus monoceros) from the Pacific Ocean and Patagonian grenadier (Macruronus magellanicus) from South America. Lowest lipid contents (0.4% and 0.8%) were found in leather jacket and cobia. Leather jacket fillets had lowest protein (16.2%) and highest sodium chloride content (4.9%). Concentrations of ∑EPA + DHA were 0.1 g 100 g^?1 for tilapia and leather jacket, 0.2 g 100 g^?1 for barramundi and cobia and 0.7 g 100 g^?1 for Patagonian grenadier. Barramundi and tilapia were characterised by high taurine content (215 and 276 mg 100 g^?1 ww.), and cobia had only low levels (41 mg 100 g^?1 ww.). Iodine contents were low and selenium levels varied between 303 and 570 μg kg^?1 ww. No sign of spoilage was detected.     

Chemical composition and anti-inflammatory activity of a pectic polysaccharide isolated from sweet pepper using a simulated gastric medium

A pectic polysaccharide named capsicuman (CA) was isolated from fresh sweet pepper by extraction with a saline solution containing hydrochloric acid (pH 1.5) and pepsin at 37 °C for 4 h. Capsicuman was shown to consist of d-galacturonic acid (GalA, 74.0%), rhamnose (Rha, 1.6%), arabinose (Ara, 2.6%) and galactose (Gal, 2.4%) residues. This polysaccharide was digestible with 1,4-alpha-d-galacturonase to yield d-GalA, thus confirming capsicuman as a pectic polysaccharide. Partial acid hydrolysis of capsicuman revealed galacturonan to be the core of the macromolecule. Purified capsicuman (CA-2) was obtained from CA by ion-exchange chromatography on DEAE-cellulose. Nuclear magnetic resonance (NMR) spectra indicated that the backbone of capsicuman contained 1,4-alpha-d-galacturonan partially substituted with methyl and O-acetyl ester groups. After oral administration to mice, capsicuman CA, CA-2 and the galacturonanic fragment of CA (CA-H) were found to decrease tumour necrosis factor-alpha TNF-alpha release and to increase production of interleukin-10 (IL-10) in lipopolysaccharide (LPS)-stimulated whole blood. This pectin was also shown to improve the survival of mice that were subjected to a lethal dose of LPS.     

Evaluation of oscillatory and shear strain behaviour for thermo-rheological plasticisation of non-ripened cheese curd: Effect of water,protein, and fat

Non-ripened cheese curd with different dry matter (34.5–47.0 g 100 g⁻¹), protein (13.4–30.4 g 100 g⁻¹), and fat (0.5–25.9 g 100 g⁻¹) contents were produced from pre-acidified milk (citric acid, pH 5.8) with different fat-to-protein ratios (0, 0.18, 0.33, 0.79, 1.60) and different curd cooking times (15 min, 30 min, 85 min). From small angle oscillatory temperature sweep and large strain capillary rheology shear experiments it was deduced that the protein content increases and fat decreases maximal loss tangent and storage modulus. This is discussed in relation to suggested changes in casein micelle voluminosity with temperature. A critical shear stress above which the flow behaviour changes from regular to melt fracture behaviour was observed. This is explained by shear jamming and the frequency dependency of the sol–gel transition.     

Semiochemical modulation of host preference of Callosobruchus maculatus on legume seeds

Host preference of Callosobruchus maculatus (F.) on seeds of three legume cultivars, Ife-brown and black-eyed cowpeas [Vigna unguiculata L. (Walp)], and soybean (Glycine max L.), was investigated. Mated female C. maculatus showed high (90–95%) attraction to the three legume cultivars in Y-tube bioassays. However, the weevils discriminated among the cultivars in four-choice tests and showed greater attraction to Ife-brown cowpea (50%) than to soybean (30%) and black-eyed cowpea (15%). Coupled gas chromatography-electroantennography (GC-EAD) and GC–MS analyses of the headspace volatile organic compounds (VOCs) emitted by the legume seeds identified 2-ethyl hexanol as the principal EAD active component. Emission of 2-ethyl hexanol was two-fold greater in Ife-brown cowpea (∼0.54 μg g⁻¹ seeds) compared with black-eyed cowpea (∼0.23 μg g⁻¹ seeds) and soybean (∼0.21 μg g⁻¹ seeds). Synthetic 2-ethyl hexanol attracted 68% of female C. maculatus at 0.01 μg dose in Y-tube bioassays. These results demonstrated that host preference in C. maculatus is odor-mediated, and identified 2-ethyl hexanol as a potential attractant for C. maculatus.     

Mercury speciation in the muscle of two commercially important fish,hake (Merluccius merluccius) and striped mullet (Mullus barbatus) from the Mediterranean sea: estimated weekly intake

Total mercury and methylmercury concentrations were measured in the muscle tissue of two fish species from the Ionian and Adriatic seas. Higher total mercury and methylmercury concentrations were detected in striped mullet (Mullus barbatus), a benthic species (Ionian sea: Hg=0.40 μg g⁻¹ wet wt, MeHg=0.40 μg g⁻¹ wet wt; Adriatic sea: Hg=0.49 μg g⁻¹ wet wt, MeHg=0.44 μg g⁻¹ wet wt), than in hake (Merluccius merluccius), a pelagic species (Ionian sea: Hg=0.09 μg g⁻¹ wet wt, MeHg=0.09 μg g⁻¹ wet wt; Adriatic sea: Hg=0.18 μg g⁻¹ wet wt; MeHg=0.16 μg g⁻¹ wet wt). Total mercury residues were determined in all samples of both species from the Adriatic sea, while levels below the limit of detection were registered in 25% and 11%, respectively, of striped mullet and hake samples from the Ionian sea. In 18.8% and 22.2% of striped mullet samples from the Ionian and Adriatic seas, respectively, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg=0.5 μg g⁻¹ wet wt). In the two different species, mercury was present almost completely in the methylated form with mean percentages between 60% and 100%. The estimated weekly intake for total mercury was below the established the provisional tolerable weekly intake (PTWI) for both species, though their consumption provides a methylmercury intake above the WHO safety limit.