Assessment of antioxidant activity and rheological properties of wheat and buckwheat milling fractions

This study examined the antioxidant properties of the ethanolic extracts of wheat milling fractions (wheat flour type 500 and type 850, and bran) and their polyphenol and tocopherol content, and rheological characteristics of wheat dough supplemented with buckwheat flours (light and wholegrain). The results obtained in this study were correlated with our previously published data on wheat flour type 400, wholegrain wheat flour and buckwheat flours.Buckwheat flours exhibited significantly higher (P < 0.05) antiradical activity on hydroxyl (OH), superoxide anion (O₂⁻) and (1,1-diphenyl-2-picrylhydrazyl) DPPH radicals, antioxidant activity and reducing power than all investigated wheat milling fractions when their corresponding IC₅₀ values were compared.The rheological parameters of wheat dough supplemented with light and wholegrain buckwheat flour (0-50%) were obtained by using Mixolab. Results indicated changes in protein and starch properties of dough.The obtained results indicate the benefit of using buckwheat flours in wheat-based food products, i.e. their contribution in functional and tailor-made-food production.     

Studies on bioactivities of tea (Camellia sinensis L.) fruit peel extracts: Antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro

Tea fruit peel is the main byproduct during manufacture of tea seed oil. The great increase in tea seed oil production in recent years brings the challenge of finding application for tea fruit peel. The aims of this study were to obtain tea fruit peel extracts enriched with bioactive compounds by several solvent extraction methods and to evaluate their antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro. Flavonoids and phenolics were accumulated in ethyl acetate, butanol, and chloroform fractions, and these fractions possessed much better antioxidant activities, including scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation radicals (ABTS⁺), and reducing activity, compared with those of the 75% ethanol extract and water fraction. Moreover, the ethyl acetate, butanol, and chloroform fractions exhibited excellent inhibitory activity against α-glucosidase, much stronger than that of the positive control (acarbose). These fractions also showed mild inhibition on α-amylase activity.     

Prolonged tempe-type fermentation in order to improve bioactive potential and nutritional parameters of quinoa seeds

The effect of 40 h solid-state fermentation with Rhizopus oligosporus on selected parameters of white and coloured quinoa was studied, as compared to standard (30 h) product and cooked seeds.The reducing power (RP) and the activity against synthetic free radicals of standard tempe were higher by on average 140% (white) and 64% (coloured quinoa) than that of cooked seeds. The OH scavenging activity was increased by more than 7 fold (white), and over 2 fold (coloured quinoa). Prolongation of the fermentation caused further improvement in this potential, on average by 27% (OH, RP) and 24% (DPPH, ABTS⁺ assays). The soluble phenols i.e. vanillic acid, protocatechuic acid and rutin levels in 40 h tempe were significantly higher than in cooked quinoa. Fermented products contained 470% (white) and on average 150% (coloured quinoa) more riboflavin and 100% more thiamine (white quinoa) than cooked seeds. The levels of total protein, free amino acids and proteins releasable during the in vitro digestion, were improved as a result of 40 h fermentation. The essential amino acids profile of quinoa tempe was consistent with the reference pattern.The prolonged tempe-type fermentation of quinoa can be recommended as a method of the value-added food production.     

Chemical composition of the essential oil and antioxidant activity of methanolic extracts from fruits and flowers of Hypericum lydium Boiss.

This study was conducted to evaluate the essential oil composition and antioxidant activity of methanolic extracts from fruits and flowers of Hypericum lydium Boiss., a wild growing species of the Turkish flora. The antioxidant activities were determined through several biochemical assays. Both extracts showed an inhibitory effect against the formation of TBARS in a phosphatidylcholine liposome model system, moderate scavenging effect on DPPH and superoxide radicals, prominent reducing power and inhibitory effect on deoxyribose degradation in both the nonsite and site-specific assay, but a greater hydroxyl radical scavenging activity was observed in the non-site specific assay, suggesting that the extracts were better at scavenging hydroxyl radicals than at chelating iron. Correlation analysis indicated that there was a linear relationship between antioxidant potency, free-radical scavenging activity, reducing power and the content of flavonoids of fruits and flowers extracts. The essential oils obtained by hydrodistillation were analyzed by GC and GC-MS. In total forty-three compounds were identified. The most abundant components were monoterpenes hydrocarbons represented principally by α-pinene. The tested oil showed no antioxidant activity.     

Nematicidal efficacy of isothiocyanates against root-knot nematode Meloidogyne javanica in cucumber

Isothiocyanates (ITCs), a series of new nematicides of the -NCS group, were evaluated for their efficacy against root-knot nematode Meloidogyne javanica. Of the compounds tested, AllylITC, AcITC, EtITC, BzTC, BzITC, 1-PEITC and 2-PEITC showed in vitro irreversible nematicidal activity against second-stage juveniles of M. javanica, following exposure for 72 h at concentrations as low as 5 μg mL⁻¹. When exposed to AllylITC, AcITC and EtITC at lower concentrations, motile juveniles also became irreversibly immobile in 3 days, with a LC₅₀ value at 2.76, 2.53 and 3.05 μg mL⁻¹, respectively. In the pot experiments, 1.0 ml AllylITC and 1.1 ml AcITC per kg of soil controlled M. javanica, similarly to or better than metam sodium at its recommended dose. Similar results were obtained in the field experiments using 1.0 kg AllylITC or 1.0 kg AcITC ha⁻¹. Based on the results of this study, AllylITC and AcITC have potential to be used as new bio-fumigant nematicides.     

Evaluation of antioxidant activities of the edible and medicinal Suaeda species and related phenolic compounds

Antioxidants are the chemical substances that reduce or prevent oxidation. The present study aimed to assess in vitro and ex vivo antioxidant activities of four acetonic extracts Tunisian halophytes (Suaeda fruticosa, Suaeda pruinosa, Suaeda mollis and Suaeda maritima). Various experimental models were used for characterization of antioxidant activities of shoot extracts. Eventually, the promising specie was subjected to phenolic identification using RP-HPLC. The analyzed shoot extracts exhibited that antioxidant activities varied considerably as function of species. The highest DPPH scavenging ability was found in S. mollis with the lowest IC₅₀ value (2.5 μg/ml), followed by S. pruinosa, S. fruticosa and S. maritima. The same tendency was observed with ferric reducing power. Concerning β-carotene bleaching assays and total antioxidant activity, results showed that S. fruticosa exhibited the highest antioxidant ability against the inhibition of β-carotene bleaching, and a better total antioxidant capacity. Moreover antioxidant capacities using ORAC method and a cell based-assay showed that S. mollis, S. fruticosa, and S. pruinosa exhibit statistically similar antioxidant activity. The identification of phenolic compounds in S. mollis extract using RP-HPLC revealed that 2,5-dihydroxybenzoic acid and rutin hydrate were the major molecules. These results suggested that Suaeda species showed a variability of their antioxidant activities.     

Enzymatic epoxidation of Sapindus mukorossi seed oil by perstearic acid optimized using response surface methodology

As a novel renewable resource, Sapindus mukorossi seed oil (SMSO) with an iodine value of 84.86 g/100 g, and containing 51.0 ± 0.9% oleic acid (18:1), 6.6 ± 0.6% linoleic acid (18:2), 1.1 ± 0.3% linolenic acid (18:3), and 23.1 ± 0.9% eicosanoic acid (20:1), was epoxidized using hydrogen peroxide as oxygen donor and stearic acid as active oxygen carrier in the presence of immobilized Candida antarctica lipase B. The effect of the amount of stearic acid on the enzymatic epoxidation was investigated. Response surface methodology (RSM) was used to study and optimize the effects of variables (reaction temperature, enzyme load, mole ratio of H₂O₂/CC-bonds, and reaction time) on the epoxy oxygen group content (EOC) of epoxidized SMSO. Results showed that stearic acid as active oxygen carrier could enhance the enzymatic epoxidation of SMSO. The variables of reaction temperature and enzyme load were the most significant in the process. A two second-order model was satisfactorily fitted the data (R² = 0.9723) with non-significant lack of fit. The optimum EOC of epoxidized SMSO was 4.6 ± 0.3% under the conditions of 50.0 °C, 7.0 h, 2.00% (relative to the weight of SMSO) enzyme load, and 4:1 mole ratio of H₂O₂/CC-bonds.     

Similarities and differences in secondary structure of viscoelastic polymers of maize α-zein and wheat gluten proteins

The secondary structure of a dough-like zein polymer was compared to the structure present in a wheat viscoelastic system using FT-IR spectroscopy. When zein was mixed at 35 °C, which is above its glass transition temperature (T_g), changes in its secondary structure suggested that the protein loses its native structure, mainly composed of α-helices (68%), and a viscoelastic system is formed by a structural rearrangement that favors β-sheet structures. This rearrangement is very similar to the structural changes observed in gluten viscoelastic polymers. Upon removal of shear stress, the zein polymer showed a rapid decrease in the proportion of β-sheet structures (from 48% to 28% after the first 3 min) in favor of unordered structures. At the same time, the viscoelasticity of the polymer decreased rapidly. In contrast, gluten, in a similar viscoelastic system and held at the same temperature, showed a fairly constant high content of β-sheet structures (49%) coinciding with the slow relaxation time typical of gluten networks after the removal of shear. We speculate that the addition of a protein capable of causing extensive and stable β-sheet formation in the zein–starch viscoelastic polymer could increase the stability and relaxation time of the zein system and, thereby, create the possibility of a zein dough with similar functionality to a wheat viscoelastic system.     

Study on the mechanism of microwave modified wheat protein fiber to improve its mechanical properties

Wheat protein is widely used in food industry. In order to expand the scope of its application on non-food field, we managed to apply the wheat protein to fiber production. To improve the mechanical properties of the fibers, we used the method of microwave modification. The best process conditions obtained by response surface analysis were a microwave power of 20.6 W/mL, microwave time of 3 min, and pH 8. Compared to non-microwaved fibers, the breaking strength was 19% higher and the elongation was 302.43% higher which indicated the microwaved fiber toughness was increased. To study the mechanism underlying the effect of microwave treatment on the improvement of mechanical properties, changes in the SH and SS content during wheat protein fiber preparation, a secondary structure study, X-ray diffraction, thermal performance analysis, SEM, surface hydrophobicity, and standard moisture regain measurement were examined. The microwaved fiber had increased SS content, α-helices, crystallinity, which may be responsible for the better mechanical properties. DSC and TG results showed that the thermal stability of microwaved fiber was increased. Additionally, SEM micrographs revealed that the structure of microwaved fibers was smoother and denser, and contained less pores than non-microwaved fibers. Although the surface hydrophobicity and standard moisture regain were decreased, microwaved fiber had good hygroscopicity, which was close to that of silk.     

The effect of gluten on the retrogradation of wheat starch

The retrogradation of amylopectin in a wheat starch and a wheat starch/gluten (10:1) blend prepared by extrusion and containing 34% water (wet weight basis) was studied using X-ray diffraction, differential scanning calorimetry and NMR relaxometry during storage at constant water content and temperature (25 °C). For both samples, amylopectin ‘fully’ retrograded after 2–3 days storage, i.e. the different parameters monitored with time to follow the retrogradation had reached their maximum value, and crystallised predominantly into the A polymorph. Under the experimental conditions used, there was no evidence of any significant effects of the presence of gluten on the kinetics, extent or polymorphism of amylopectin retrogradation.     

Inhibition of α-amylase purified fromOctopus vulgaris Lam. by albumin inhibitors from wheat flour

Octopus -amylase has been purified to homogeneity by single-step affinity chromatography on Sepharose-bound wheat albumin inhibitors. Two electrophoretically distinguishable isoamylases are obtained, both consisting of a single polypeptide chain with molecular weight 45,000. Octopus -amylase is more effectively inhibited by a monomeric than by a dimeric protein inhibitor from wheat. The inhibition is dependent on pH, temperature, and time of preincubation. Properties are compared with those of other animal -amylases.     

Identification of quantitative trait loci for β-glucan concentration in barley grain

The amount of (1 → 3),(1 → 4)-β-d glucan (β-glucan) accumulated in cell walls of barley (Hordeum vulgare L.) kernel is an important determinant for grain end-use. Grain β-glucan concentration is affected by environmental and genetic factors and usually varies from 3 to 6%. In this study, we have analyzed the β-glucan trait in a doubled-haploid (DH) population of 170 lines grown in three separate field trials. Most of the DH lines showed β-glucan values that ranged from that of the low β-glucan parent (cultivar CDC Bold; 3.3%) to that of the high β-glucan parent (breeding line TR251; 5.4%). Eighty-eight lines of the DH population were genotyped using simple sequence repeat (SSR), amplified fragment length polymorphism (AFLP) and diversity array technology (DArT) markers, which were subsequently integrated into a barley genetic map spanning 1059 cM. Interval mapping and multiple-QTL-mapping (MQM) of quantitative trait loci (QTL) from the three trials indicated seven genomic regions associated with low grain β-glucan concentration. For all putative QTLs, the low β-glucan concentration was contributed by alleles from CDC Bold except for two loci on chromosomes 5H that were derived from TR251. A major QTL located to the centromere region of chromosome 7H was identified by both mapping methods for all three trials. The 7H QTL explained up to 39% of the β-glucan concentration and genetic markers associated with the locus may be used to aid selection of high and low β-glucan barley lines.     

Postharvest decay control and quality retention in litchi (cv. McLean's Red) by combined application of modified atmosphere packaging and antimicrobial agents

The effects of modified atmosphere packaging (MAP) [bioriented polypropylene (BOPP-1 or BOPP-2)] in combination with antimicrobial agents Bacillus subtilis, 10⁷ colony-forming units (cfu) ml⁻¹; ethylenediamine tetraacetic acid, calcium disodium salt hydrate (EDTA) (0.1%); or 4-hexylresorcinol (4-HR) (0.15%) on postharvest decay control and quality retention of litchi cv. McLean's Red were assessed as possible replacements for commercial SO₂ fumigation. Fruits dipped in B. subtilis, EDTA or 4-HR (5 min) separately, blow dried (25 °C, 3 min), packed in BOPP-1, held for 18 d at 2 °C, 95% RH, and 2 d at 14 °C, 75% RH were significantly less decayed. The antagonist–BOPP-1 combination also promoted the best bacterial survival during storage. B. subtilis was observed to survive effectively in BOPP-1 (16% O₂, 6% CO₂; 90% RH), but its survival was adversely affected in BOPP-2 (5% O₂, 8% CO₂; 93% RH). Alternaria alternata and Cladosporium spp. were the major decay-causing fungi in BOPP-1 treatments, and Candida, Cryptococcus and Zygosaccharomyces were the predominant yeasts in BOPP-2 treatments. Combination treatments EDTA, 4-HR or B. subtilis in BOPP-1 inhibited polyphenol oxidase (PPO) and significantly reduced pericarp browning and severity. Although the combination treatments EDTA, 4-HR or B. subtilis in BOPP were equally effective in controlling decay and browning, the EDTA and 4-HR affected the natural pinkish-red colour of the pericarp by showing higher h° values (orange–pink). Among the combination treatments, B. subtilis+BOPP-1 had the best potential to control decay, retain the colour and the overall litchi fruit quality during a marketing chain of 20 d.     

Verbreitung des Wissens über die ‘innere’ Qualität von Gemüse und Obst in der Öffentlichkeit

Zusammenfassung Anhand praktischer Beispiele werden qualitätsrelevante Problemkreise vorgestellt und eingehend diskutiert, so Erzeugerberatung — Weg der Ware vom Erzeuger zum Verbraucher — Äußere Beschaffenheit — Innerer Wert — Präsentation der Verkaufsware — Erhaltung der Frische — Berücksichtigung ernährungsphysiologischer Kriterien. Es wird ein Publikationsmodell — bereits 1950 entwickelt — vorgeschlagen, das weite Kreise der Züchter, der Erzeuger, der Fabrikanten, des Handels und der interessierten Verbraucherschaft sowohl ansprechen als auch das Verständnis der einzelnen Gruppen untereinander wecken könnte.Denn letztlich sollte es doch im Bermühen des Erzeugers, des Transporteurs, des Handels, des Verarbeiters von Obst und Gemüse in erster Linie darum gehen, das Wohlergehen, die Gesunderhaltung des Verbrauchers im Auge zu haben. Das wäre jedenfalls die Vorstellung und Erwartung der ernährungsphysiologisch und ernährungs-hygienisch ausgerichteten Qualitätsforscher.

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Public extension about the inner Quality of Vegetables and Fruit

As usually practized in vegetable and fruit cultivation problems relevant to the inner quality are presented and discussed, e.g. Information of consumers, Shipping products from producer to consumer, External Quality — inner Quality — Offering of products — Conserving of freshness — Regarding the nutritional value.In order to evaluate these problems a close co-operation of breeders, producers, manufacturers, dealers and the interested consumers seem to be necessary. This is possible through a model and system of information, similar to the so-called AZA which were first published in 1950.

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Referat, gehalten auf der Sitzung der neukonstituierten Kommission Öffentlichkeitsarbeit der DGQ am 1.10.1976 in Geisenheim/Rhein.