Effect of hydrostatic high pressure pretreatment on flavor volatile profile of cooked rice

The impact of high hydrostatic-pressure (HHP) processing on the volatile profile of cooked Japonica rice (Wuchang) and Jasmine rice (Complete Wheel) was investigated by SPME–GC/MS. Presoaked samples were treated at 200, 400 and 600 MPa for 10 min and then cooked for volatile compound analysis. Seventy-seven compounds were identified in two cooked rice varieties: 20 aldehydes, 16 alcohols, 14 ketones, 9 arenes, 7 esters, 5 alkanes, 3 olefins and 3 hetero-cycle compounds. Results showed that both pressure level (P < 0.01) and rice variety (0.01 < P < 0.05) significantly impact the volatile compounds in rice and there is also an interaction between pressure and rice variety (P < 0.01). Overall, HPP decreased the amount of aldehydes more obviously in Complete Wheel rice than that in Wuchang variety. Both 200 and 400 MPa increased the levels of alcohols, ketones, esters and olefins, but reduced those of heterocycles, alkanes and arenes. Similar volatile change trends were found at 600 MPa except the concentration of each component was closer to that of control group. Based on the changes in the three key flavor compounds in rice (aldehydes, alcohols and ketones), the HPP process could be a suitable alternative to traditional pretreatment for improving flavor in cooked rice.     

High pressure processing manipulated buckwheat antioxidant activity,anti-adipogenic properties and starch digestibility

Effect of high pressure processing (HPP) on buckwheat nutritional properties is investigated in this study. The results indicated that the digestion of buckwheat starches of untreated and HPP treated at room temperature (RT) showed an “internal corrosion” pattern. However, an “exocorrosion” digestion behavior was observed for the starches of HPP treated sample at 45 °C, which might be due to the formation of amylose–lipid complexes during the process as revealed by X-ray diffraction (XRD). HPP treatment at 45 °C increased the antioxidant activity of the buckwheat as measured using 1,1′-diphenyl-2-picrylhydrazylvalue (DPPH) and iron chelating capacity (ICC) compared to untreated sample (P < 0.05), which might be associated with the release of bound phenolic compounds. More importantly, this is the first study to investigate the ability of buckwheat extract for inhibiting the formation of fat droplets using a C3H10T1/2 mesenchymal stem cell line, and found that the extract of buckwheat after HPP treatment at 45 °C demonstrated significant anti-adipogenic effects. This study suggested the HPP treatment at an increased temperature (45 °C) achieved a better nutritional value of the buckwheat than both untreated and treated at RT.     

Predicted truly absorbed protein supply to dairy cattle from hulless barley (Hordeum vulgare L.) with altered carbohydrate traits with multi-year samples

Hulless barley breeding lines varying in amylose (1–20% DM) and β-glucan content (5–10% DM) have been developed at the Crop Development Centre, Canada. The objectives of this large-scale study were to 1) determine and confirm the effect of these new hulless barley lines (zero-amylose waxy, CDC Fibar; 5%-amylose waxy, CDC Rattan; normal-amylose, CDC McGwire and high-amylose, HB08302) with altered carbohydrate traits on 1) metabolic characteristics of protein; 2) intestinal digestion of various nutrients and 3) modeling nutrient supply from these barley varieties by using NRC Dairy 2001 model and DVE/OEB system. CDC Copeland was included as a hulled barley control. Among the hulless barley lines, CDC Fibar contained the highest and CDC McGwire contained the lowest total digestible protein (TDP: 147 vs. 116 g/kg DM). HB08302 was greater (P < 0.05) in intestinal digestible protein (IDP: 40.6% RUP) but relatively lower (P < 0.05) in total digestible protein (TDP: 120 g/kg DM). Compared with hulless barley, hulled barley showed relatively lower (P < 0.05) intestinal digestible protein (38 vs. 53 g/kg DM) and total digestible protein (102 vs. 129 g/kg DM). In modeling nutrient supply from the DVE/OEB system, the results showed hulled barley was lower (P < 0.01) in true protein supplied to the small intestine (TPSI: 127 vs. 142 g/kg DM), lower in truly absorbed rumen bypassed feed protein in small intestine (ABCP^DVE: 43 vs. 58 g/kg DM), lower in truly absorbed protein in the small intestine (DVE: 95 vs. 111 g/kg DM), and lower in degraded protein balance (OEB^DVE: −39 vs. −23 g/kg DM) than the hulless barley lines but greater (P < 0.01) in undigested inorganic matter (9 g/kg DM). From NRC Dairy 2001 model, CDC Fibar was greater (P < 0.05) in degraded protein balance (OEB^NRC: −30 g/kg DM) and metabolizable protein (MP: 118 g/kg DM) than the other hulless barley lines, while hulled barley was relatively lower (P < 0.01) in total metabolizable protein (MP: 83 vs. 105 g/kg DM). Our correlation results suggested that TDP was negatively correlated to amylose (r = −0.85, P < 0.001) but positively correlated to β-glucan level (r = 0.74, P < 0.001) in hulless barley cultivars. The DVE and OEB^DVE as well as MP were negatively correlated (P < 0.05) to amylose level but positively correlated to β-glucan level (P < 0.05). In conclusion, altered carbohydrate traits in the hulless barley varieties have the potential to increase intestinal nutrient availability to ruminants and significantly improved the truly absorbed protein supply to dairy cattle compared to hulled barley. Hulless barley with lower amylose and higher β-glucan level could provide greater (P < 0.05) truly digested protein in the small intestine, better synchronized available energy and N and increase metabolizable protein supply to ruminants.     

Formulating low glycaemic index rice flour to be used as a functional ingredient

Amylose and resistant starch (RS) content in rice flour were manipulated. The experiment was conducted using a full factorial design. Rice flour with average amylose content of 20 and RS content of 0.5 g/100 g dry sample was fortified with pure amylose from potato and high RS modified starch to reach the final amylose content of 30, 40 and 50 and RS content of 2, 4 and 6 g/100 g dry sample. The fortified rice flours were examined for their gelatinisation properties, in-vitro enzymatic starch digestion and gel textural properties. It was found that amylose and RS significantly affect all the fortified rice flour properties (p < 0.05). High amylose and RS improved starch digestion properties, reducing the rate of starch digestion and lowering the glycaemic index (GI) values. Amylose had a more pronounced effect on the fortified rice starch properties than RS. In this study, the fortified rice flour which contained amylose and RS of approximately 74 and 9 g/100 g dry sample respectively was used to produce rice noodles. The noodles exhibited low GI values (GI < 55). However, amylose and RS affected the textures of rice noodles providing low tensile strength and break distance (extensibility).     

The molecular structure features-immune stimulatory activity of arabinoxylans derived from the pentosan faction of wheat flour

Recently, the immune stimulation properties of cereal arabinoxylans (AX) have been reported. The aims of this study were to identify the molecular features and potential immune stimulation activities of AX and enzymatic modified arabinoxylan (AXE) from the pentosan fraction of wheat flour.The results of molecular characterization of AX and AXE show that AXE contains a larger portion (85.7%) of low Mw arabinoxylans (≤25 kDa) and has a higher degree of branch substitution (0.81 ± 0.01) compared to AX (49.5% and 0.62 ± 0.02). In in vitro testing, the ability of AX and AXE to stimulate immune cells, as measured by NO₂⁻ production by U937 cells and IL-8 secretion by Caco-2 cells were found to be dose–dependent in the range tested (100–5000 μg/mL p ≤ 0.05). AXE showed a greater activity at each concentration (100–5000 μg/mML) than AX (p ≤ 0.05).In conclusion, the greater immune stimulating activity of AXE may be associated with its low Mw (≤25 kDa) and a higher degree of branch substitution (0.81 ± 0.01).     

Molecular characterization of storage proteins for selected durum wheat varieties grown in different environments

The variations of the amounts of individual high molecular weight glutenin subunits (HMW-GS), of the ratios HMW-GSy to HMW-GSx and HMW-GS to low molecular weight glutenin subunits (LMW-GS) and of protein content were evaluated for eight durum wheat cultivars in two regions using four fertilizer combinations during two successive years. All measured parameters showed significant variation with genotypes (G), environments (E) and fertilizers (F). The interaction E × G × F was highly significant for glutenin amount variation. Amongst cultivars possessing HMW-GS 20, landraces seem to better value the N-fertilizer use for the accumulation of HMW-GSy than high yielding cultivars. Both HMW-GSy to HMW-GSx and HMW-GS to LMW-GS ratios were found to be positively correlated (p < 0.05) with total protein content.     

Enhancement of biocontrol efficacy of Pichia membranaefaciens by hot water treatment in postharvest diseases of citrus fruit

Effects of hot water treatment (HWT; 53 °C for 2 min) and Pichia membranaefaciens, either alone or in combination, on controlling Penicillium italicum, Penicillium digitatum, and natural infection in citrus fruit were investigated. Results showed that the combined treatment significantly reduced disease incidence and lesion diameters of blue and green molds in artificially inoculated fruit whether the pathogens were inoculated after or before the treatment compared with the treatment of P. membranaefaciens or HWT alone. The combination of P. membranaefaciens with HWT was as effective as the fungicide treatment in natural infection trials. Application of HWT did not affect the growth of P. membranaefaciens in the wounds of citrus fruit at 20 °C or 4 °C. P. membranaefaciens combined with HWT effectively enhanced the phenylalanine ammonia-lyase, peroxidase, polyphenoloxidase, chitinase, and β-1,3-glucanase activities and stimulated the synthesis of phenolic compounds. These results suggest that the use of HWT is a useful approach to improve the efficacy of P. membranaefaciens in postharvest diseases of citrus fruit.     

Quinoa (Chenopodium quinoa Willd.) protein hydrolysates with in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant properties

The potential of quinoa to act as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides was studied. A quinoa protein isolate (QPI) with a purity of 40.73 ± 0.90% was prepared. The QPI was hydrolysed at 50 °C for 3 h with two enzyme preparations: papain (P) and a microbial papain-like enzyme (PL) to yield quinoa protein hydrolysates (QPHs). The hydrolysates were evaluated for their DPP-IV inhibitory and oxygen radical absorbance capacity (ORAC) activities. Protein hydrolysis was observed in the QPI control, possibly due to the activity of quinoa endogenous proteinases. The QPI control had significantly higher DPP-IV half maximal inhibitory concentrations (IC₅₀) and lower ORAC values than QPH-P and QPH-PL (P < 0.05). Both QPH-P and QPH-PL had similar DPP-IV IC₅₀ and ORAC values. QPH-P had a DPP-IV IC₅₀ value of 0.88 ± 0.05 mg mL⁻¹ and an ORAC activity of 501.60 ± 77.34 μmol Trolox equivalent (T.E.) g⁻¹. To our understanding, this is the first study demonstrating the in vitro DPP-IV inhibitory properties of quinoa protein hydrolysates. QPHs may have potential as functional ingredients with serum glucose lowering properties.     

Thermal degradation kinetics of bioactive compounds from black rice flour (Oryza sativa L.) extracts

The effect of thermal processing on the degradation of the phytochemicals in black rice flour by means of fluorescence spectroscopy and degradation kinetics was investigated. In order to investigate the influence of food matrices, a comparative analysis between integral rice flour and different fractions was performed. The preliminary compositional results suggested a higher content in phytochemicals in fraction four of the seven fractions of black rice flour, which was sifting through a sieve with a diameter of 180 μm. The compositional complexity was highlighted by fluorescence spectroscopy. The heat-treatment caused structural changes that led to red- or blue-shifts in maximum emission. The first-order kinetic model was used to describe the mechanism of degradation. The activation energies were 10.07 ± 1.04 kJ/mol for total polyphenolic, 7.26 ± 0.58 kJ/mol for total monomeric anthocyanins and 6.71 ± 1.12 kJ/mol for antioxidant activity in case of integral flour extract. For fraction four extract obtained by, the E_a values were: 3.51 ± 0.53 kJ/mol, 11.49 ± 1.47 kJ/mol, 15.80 ± 1.50 kJ/mol and 19.91 ± 3.27 kJ/mol, respectively. The calculated values of the activation energy revealed higher temperature dependence of total polyphenols in integral flour and of antioxidant activity in fraction four, respectively.     

Characterisation of starch during germination and seedling development of a rice mutant with a high content of resistant starch

To acquire a better understanding of whether RS influences the dynamics of in vivo starch digestion and seed vigour, the high-RS rice mutant RS4 (RS ca. 10%) and the wild type R7954 were used to investigate total amylase activity, seedling vigour, starch content and starch granule structure during germination. RS4 exhibited similar seed vigour to R7954. Amylose and amylopectin in R7954 showed synchronous degradation throughout the whole process, while amylopectin was hydrolysed significantly faster than amylose in RS4 during the earlier germination stages. The starch residues of RS4 after germination (GD) lost endotherm peaks and showed a special X-ray diffraction pattern with only two peaks at around 16.90° and 21.62°, probably due to remnants of amylopectin and its tight crosslinking with the cell wall. The remaining starch after 10 GD, primarily amylopectin may make a critical contribution to total resistant starch content. These results indicated that RS had no negative impact on seed vigour in rice lines, although RS cannot be hydrolysed by α-amylase from human and animal in vitro. By appropriately increasing the special amylopectin fraction, a new breeding programme of high RS crops and improvement in the eating quality of high RS rice varieties might be achieved.     

Modeling the effects of microfluidization conditions on properties of corn bran

Corn bran was microfluidized through a 200-μm channel in the pressure range of 124.1–158.7 MPa for 1–5 passes following the central composite experimental design. Physicochemical properties and antioxidant properties of microfluidized bran samples were measured and fitted to the second order polynomial model. The response surface equations obtained showed that all the properties examined had a positive linear relationship with pressure and a negative quadratic relationship with number of passes except for ABTS radical scavenging activity which was quadratically related to both processing parameters. The number of passes generally had a more pronounced effect on the examined properties compared with pressure. Within the experimental range, the maximum values of swelling capacity, water-holding capacity, and oil-holding capacity were respectively 10.62 ml/g d.w. (at 158.7 MPa), 5.49 g water/g d.w. (at 158.7 MPa), and 4.61 g oil/g d.w. (at 124.1 MPa); the maximum values of surface reactive phenolic content, DPPH and ABTS radical scavenging activities were 148.80 mg/FAE g d.w. (at 158.7 MPa), 50.02 μmol TE/g d.w. (at 158.7 MPa), and 47.90 μmol TE/g d.w. (at 145.9 MPa), respectively. All maximum values of the properties occurred at 5 passes.     

Effect of high molecular weight glutenins and rye translocations on soft wheat flour cookie quality

The influence of high molecular weight glutenin subunits (HMW-GS) on wheat breadmaking quality has been extensively studied but the effect of different Glu-1 alleles on cookie quality is still poorly understood. This study was conducted to analyze the effect of HMW-GS composition and wheat-rye translocations on physicochemical flour properties and cookie quality of soft wheat flours. Alleles encoded at Glu-A1, Glu-B1 and Glu-D1 locus had a significant effect over physicochemical flour properties and solvent retention capacity (SRC) profile. The null allele for Glu-A1 locus presented the highest cookie factor observed (CF = 7.10), whereas 1BL/1RS and 1AL/1RS rye translocations had a negative influence on CF. The three cultivars that showed the highest CF (19, 44 and 47) had the following combination: Glu-A1 = null, Glu-B1 = 7 + 8, Glu-D1 = 2 + 12 and no secalins. Two prediction equations were developed to estimate soft wheat CF: one using the HMW-GS composition and the other using physicochemical flour parameters, where SRCsuc, SRC carb, water-soluble pentosans, damaged starch and protein turned out to be better CF predictors. This data suggests that grain protein allelic composition and physicochemical flour properties can be useful tools in breeding programs to select soft wheat of good cookie making quality.     

Aflatoxin in maize,a multifaceted answer of Aspergillus flavus governed by weather,host-plant and competitor fungi

Aspergillus section Flavi is able to produce aflatoxins (AFs) in vitro down to 0.85 a_w with a potential maximum occurring between 0.95 and 0.99 a_w, while in the field AFs increased significantly with kernel humidity below 0.95 a_w. In order to clarify this apparent discrepancy, a 3-year field trial with artificial inoculation of maize ears with Aspergillus flavus strains was organised. The co-occurrence of Aspergillus section Flavi and Gibberella fujikuroi species complex (Gfsc) was observed. The incidence of A. flavus was significantly influenced by the year and negatively related to Gfsc incidence. In 2012, when the highest temperature and the lowest rain were registered, aflatoxin B₁ (AFB₁) content was the highest and a_w < 0.95 in kernels was measured early throughout the growing season. In 2013 and 2014, the temperature was lower and rain more abundant, and a_w decreased below 0.95 only close to harvest and AFB₁ contamination was limited. The possibility of describing/predicting reasonably well a_w dynamic based on temperature, (degree day) was confirmed. With a_w > 0.95, a positive correlation between AFB₁ production rate and a_w was found, but a negative correlation resulted with a_w < 0.95. Other factors than a_w play a role, but a_w = 0.95 should be considered as an indicator of suitable conditions for rapid aflatoxin accumulation.     

Effects of the invasive tomato red spider mite (Acari: Tetranychidae) on growth and leaf yield of African nightshades

The tomato red spider mite, Tetranychus evansi Baker and Pritchard, is one of the most serious pests of solanaceous crops in Africa. Field experiments were conducted to investigate its effects on the growth and leaf yield of five African nightshade species viz. Solanum americanum, S. sarrachoides, S. scabrum, S. tarderemotum and S. villosum during the 2008 and 2009 growing seasons. Plants were infested with 2–4 day-old female spider mites which were allowed to multiply. The number of mite motiles increased throughout the growing season in unsprayed plots and this number varied significantly between the African nightshade species. Except for S. sarrachoides, leaf damage was high on the other four Solanum species irrespective of the spraying regime during both seasons. However, S. scabrum had a significantly greater leaf area ratio (ratio of leaf area to total plant weight) and specific leaf area (ratio of leaf area to total leaf dry weight) during both seasons. Overall yields were 1.5 times more in S. scabrum and S. sarrachoides compared to S. americanum, S. tarderemotum and S. villosum. Our results show that T. evansi infestation affects the leaf area ratio and specific leaf area of African nightshade species differentially which eventually determines the plant's overall leaf yield. These findings present an opportunity for evaluation and selection of African nightshade species that can withstand spider mite infestation in small holder farms for increased vegetable production in Africa.     

Antioxidant,anti-amylase and anti-glycation potential of brans of some Sri Lankan traditional and improved rice (Oryza sativa L.) varieties

Brans of 23 traditional and 12 improved (both red and white) rice varieties in Sri Lanka were screened for anti-amylase and anti-glycation activities in vitro. Varieties which showed the highest inhibitory activities at screening were further investigated for anti-glucosidase and glycation reversing as anti-diabetic properties. The same varieties were studied for selected antioxidant properties. Significantly high anti-amylase and anti-glycation activities were observed for bran extracts of red varieties compared to white varieties at screening. Traditional red rice varieties, Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti, exhibited significant and dose dependent anti-amylase, anti-glycation and glycation reversing activities. These varieties also showed marked antioxidant properties. It is concluded that brans of Sri Lankan traditional red rice varieties Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti may be potential food supplements for diabetes.     

Effects of selected extrusion parameters on physicochemical properties and in vitro starch digestibility and β-glucan extractability of whole grain oats

Whole grain oat flour was extruded under different moisture contents (15%, 18%, 21%), barrel temperatures (100 °C, 130 °C), and screw speeds (160 rpm, 300 rpm, 450 rpm), and selected physicochemical properties, in vitro starch digestibility, and β-glucan extractability of the extrudates were analyzed. An increase in screw speed resulted in an increase in radial expansion index, water absorption index, and water solubility index. Screw speed significantly affected slowly and rapidly digestible starch. Moderate screw speed (300 rpm) led to higher slowly digestible starch with an accompanying decrease in rapidly digestible starch. Low moisture conditions (15%) resulted in the highest resistant starch and water-extractable β-glucan. Under the conditions used in this study, extrusion did not result in changes in water-extractable β-glucan molecular weight. Thus, extrusion might be beneficial in improving functionality and consumer acceptability by affecting physicochemical properties, in vitro starch digestibility, and β-glucan extractability of oat extrudates.     

Alkylresorcinol composition allows the differentiation of Triticum spp. having different degrees of ploidy

Total alkylresorcinol (AR) content and homologue composition were assessed in whole grain flours of 15 varieties each of bread wheat, durum, spelt, emmer, and einkorn grown in four different environments. Bread wheat (761 ± 92 μg/g DM) and spelt (743 ± 57 μg/g) belonging to the hexaploid species showed higher AR concentrations than the tetraploid durum (654 ± 48 μg/g, p < 0.05), while the concentrations found in the diploid einkorn (737 ± 91 μg/g) and the tetraploid emmer (697 ± 94 μg/g) did not significantly differ from the other species. The AR content showed a remarkable heritability and, thus, seemed to be mainly determined by genetic factors. If ARs were assumed to be deposited within a specific AR-rich layer of the kernel, AR levels of all varieties would easily surpass their minimal inhibitory concentrations against fungal pathogens within this barrier layer. Although the AR carrying a C21:0 side chain was the main homologue in all species, the levels of all AR homologues and their relative composition significantly differed between hexaploid (bread wheat and spelt), tetraploid (durum and emmer) and diploid (einkorn) species. Consequently, a clear-cut differentiation of Triticum species and derived whole grain flours according to their degrees of ploidy was established based on concentrations of saturated C₁₇-, C₁₉-, C₂₁-, C₂₃-, and C₂₅-substituted ARs.     

Antioxidant properties of wheat and rye bran extracts obtained by pressurized liquid extraction with different solvents

Rye and wheat brans are valuable sources of bioactive compounds, which could be used for the development and commercialization of high added value functional ingredients such as dietary antioxidants. The aim of this study was to evaluate antioxidant potential of rye and wheat bran using different polarity solvents. Cereal brans were ground to four different particle size fractions and extracted at 10.3 MPa pressure and 80 °C temperature by consecutive application of hexane, acetone and methanol:water (80:20%). The highest extract yield was obtained from rye bran using methanol-water; particle size in most cases had a significant effect. Antioxidant potential of extracts was assessed by ABTS^+•, DPPH^• scavenging, ORAC and total phenols content (TPC) assays. Extraction solvent had a major influence on TPC and antioxidant activity of the extracts. The most active extracts were obtained using methanol:water; rye bran extracts, in general, were stronger antioxidants than wheat bran extracts. For the majority of assays, reduction of particle size resulted in higher antioxidant activity values. However, ABTS^+• scavenging was found to decrease by decreasing particle size of rye bran used for extraction.     

Effect of Pichia membranaefaciens on ROS metabolism and postharvest disease control in citrus fruit

The yeast Pichia membranaefaciens has antagonistic effects against a wide range of phytopathogenic fungi that cause postharvest fruit decay. This work evaluated the effects of P. membranaefaciens on the reactive oxygen species (ROS) metabolism and disease control in harvested citrus fruit (Citrus sinensis L. Osbeck). The lesion diameter caused by Penicillium italicum and Penicillium digitatum on citrus fruit was remarkably reduced when the fruit was point-inoculated or dipped in a suspension of P. membranaefaciens at 1 × 10⁸ CFU mL⁻¹. The application of P. membranaefaciens on citrus fruit enhanced the activity of superoxide dismutase, ascorbate peroxidase, and glutathione reductase, as well as the levels of hydrogen peroxide, the superoxide anion and glutathione, but inhibited the decreasing ascorbic acid content. Furthermore, catalase activity was decreased by the same treatment. These results indicated that yeast treatment induced the synthesis of antioxidant enzymes which might have antagonistic effects against postharvest green and blue mold infection in citrus fruit.