Characterization of a formaldehyde-free cornstarch-tannin wood adhesive for interior plywood

This study investigated the physical properties (rheological and thermogravimetric analysis) of cornstarch-tannin adhesives and the mechanical properties (dry tensile strength and 3-point bending strength) of plywood made using cornstarch-tannin adhesives. This adhesive was evaluated for its utility in interior plywood manufacture. The optimum cure temperature and cure time of cornstarch-tannin adhesives were 170°C and 4?min, respectively. Plywood bonded with formaldehyde-free cornstarch-tannin adhesive exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. It was found that cornstarch-tannin panels which do not contain formaldehyde and with an emission equal to that of heated but unbound wood can be obtained by the use of hexamethylenetetramine (hexamine) as hardener. The work has indicated that an environmentally friendly wood adhesive can be prepared from a natural renewable resource (cornstarch and wattle tannin) for bonding interior-type plywood.     

Development and optimization of a new formaldehyde-free cornstarch and tannin wood adhesive

The development and optimization of a new, environment-friendly adhesive made from abundant and renewable cornstarch and tannin is described in this study. At present, the production of wood composites mainly relies on petrochemical- and formaldehyde-based adhesives such as phenol-formaldehyde (PF) resins and urea-formaldehyde (UF) resins. Formaldehyde-free cornstarch plus tannin adhesives were evaluated for mechanical and physical properties (shear strength, rheological characterisation and thermogravimetric analysis). First, optimized conditions for the preparation of cornstarch-sodium hydroxide wood adhesives were determined. The parameters studied were the following: total solids content of the adhesives, sodium hydroxide concentration and sodium hydroxide/cornstarch volume ratio. The highest shear strength results appeared to be 0.5 sodium hydroxide/cornstarch volume ratio when using concentrations of cornstarch (65% p/v H₂O) and sodium hydroxide (33% p/v H₂O). The optimum cure temperature was 170 °C and the cure time 4 min. The addition of two types of tannin-based adhesives, Mimosa and Quebracho, with hexamethylenetetramine (hexamine) hardener to the cornstarch-sodium hydroxide formulation improved the shear strength and decreased the viscosity of adhesives.     

Potential of shortening pressing time or reducing pressing temperature for plywood resinated with PF resin modified using alcohols and esters

The study was an analysis of the potential to shorten pressing time or reduce pressing temperature for plywood resinated with alcohol- and ester-modified PF resin. Birch and pine plywoods were produced using such modified resin at a temperature range of 135 to 115?°C, at a constant pressing time (4 min) and at pressing times ranging from 240 to 150 s at a constant pressing temperature (135?°C). Tests showed that the application of PF resin modified with polyols and esters makes it possible, under standard pressing conditions, i.e. 135?°C and pressing time of 4 min, to produce plywood with improved properties in comparison to respective control plywoods. Moreover, it was shown that the used modifiers enhance resin reactivity, facilitating an adequate course of resin curing, resulting in the manufacture of plywoods with good properties even at a pressing temperature reduced by 20?°C or pressing time shortened to 150 s.     

Use of a highly sensitive latex reagent with amino acid spacer for determination of C-reactive protein concentration in a variety of liver diseases

C-reactive protein (CRP) is a major acute-phase protein, which is extremely important in inflammatory disease diagnosis. CRP is rapidly elevated in various diseases as a result of tissue injury, infection and inflammation. Recently, many reports have shown its usefulness as a risk marker for arteriosclerosis and metabolic syndrome. However, the lack of sensitivity of existing CRP assays has hampered CRP testing in conditions associated with viral infections, where CRP levels typically elevate only marginally. In this report, we prepared a novel, ultra-sensitive latex-based CRP test using amino acid spacers with a high sensitivity and a wider assay range. Our method of conjugating latex beads enabled us to measure CRP in the range of 5-500?ng/mL in patient sera. Furthermore, we studied CRP levels in patients with various liver diseases, such as chronic hepatitis, liver cirrhosis and hepatic carcinoma, in order to examine the correlation between severity of liver dysfunction and CRP levels, and to examine the likelihood of recurrence of liver dysfunction. The reagent was simple to prepare and sensitive during clinical investigation, where it discriminated clearly between normal subjects and those with liver diseases. Therefore, we conclude that our ultra-sensitive CRP assay will contribute greatly to the clinical study of hepatic disorders.     

Relevance of the air–water interfacial and foaming properties of (modified) wheat proteins for food systems

A shift from animal protein- to plant protein-based foods is crucial in transitioning toward a more sustainable global food system. Among food products typically stabilized by animal proteins, food foams represent a major category. Wheat proteins are ubiquitous and structurally diverse, which offers opportunities for exploiting them for food foam and air–water interface stabilization. Notably, they are often classified into those that are soluble in aqueous systems (albumins and globulins) and those that are not (gliadins and glutenins). However, gliadins are at least to an extent water extractable and thus surface active. We here provide a comprehensive overview of studies investigating the air–water interfacial and foaming properties of the different wheat protein fractions. Characteristics in model systems are related to the functional role that wheat proteins play in gas cell stabilization in existing wheat-based foods (bread dough, cake batter, and beer foam). Still, to further extend the applicability of wheat proteins, and particularly the poorly soluble glutenins, to other food foams, their modification is required. Different physical, (bio)chemical, and other modification strategies that have been utilized to alter the solubility and therefore the air–water interfacial and foaming properties of the gluten protein fraction are critically reviewed. Such approaches may open up new opportunities for the application of (modified) gluten proteins in other food products, such as plant-based meringues, whippable drinks, or ice cream. In each section, important knowledge gaps are highlighted and perspectives for research efforts that could lead to the rational design of wheat protein systems with enhanced functionality and overall an increased applicability in food industry are proposed.     

Validation of a lateral flow test (MRLAFMQ) for the detection of aflatoxin M1 at 50 ng l−1 in raw commingled milk

Aflatoxin M₁ contamination in dairy products is a risk when feedstuff contaminated with aflatoxin B₁ produced by moulds is consumed by milk-producing animals. Milk can be screened for aflatoxin M₁ at the European Union maximum limit of 50 ng l^?1 by a lateral flow test, the MRLAFMQ (Aflatoxin M1) Test. The method takes 15 min with no milk dilution or a sample preparation step. The lateral flow assay was validated at the Technology and Food Science Unit of the Institute for Agricultural and Fisheries Research (ILVO-T&V) according to European Union guidelines using fortified raw milk samples. A detection capability of 50 ng l^?1 was demonstrated with a false negative rate lower than 2% at 50 ng l^?1 and a false positive rate of less than 0.3%. Quantitative readings had a mean bias of +2 to 6 ng l^?1 at 50 ng l^?1 with a standard deviation of 5–8 ng l^?1. Based on the validation results, the test could be considered appropriate for milk screening prior to milk unload at dairies.     

Efficient hydrolytic reaction of an acetate ester with fungal lipase in a liquid-liquid interface bioreactor (L-L IBR) using CaCO₃-coated ballooned microsphere

In a liquid-liquid interface bioreactor using a CaCO?-coated ballooned microsphere, 2-ethylhexyl acetate was efficiently hydrolyzed to 2-ethyl-1-hexanol with Absidia coerulea NBRC 4423 compared with using talc-coated or non-coated ballooned microsphere. It was assumed that CaCO? brought about stabilization of lipase by Ca2? and maintenance of medium pH.     

The wettability and bonding performance of densified VTC beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) bonded with phenol–formaldehyde adhesive and liquefied wood

The influence of viscoelastic thermal compression (VTC) on surface wettability and bonding performance of wood was evaluated. Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with the VTC process to different degrees of densification. Control and densified strips were bonded with phenol–formaldehyde (PF) adhesive and liquefied wood (LW). Shear strength of bonded assemblies was determined after 1 week of conditioning at 20 °C and relative humidity of 65 %. Wettability was determined on the basis of the contact angle of water, PF adhesive, and LW using the Wilhelmy method. Results showed that densification of beech and spruce wood did not significantly affect the shear strength of specimens bonded with PF adhesive. In beech assemblies bonded with LW shear strength decreased significantly with increased density, whereas in bonded spruce specimens decrease of shear strength was not significant. It was found that degree of densification and bonding process used in the study were not appropriately chosen for spruce wood specimens, since major deformations after the bonding process occurred. Wettability changed significantly after densification. Contact angle of water and LW increased after densification, whereas contact angle of PF showed inverse trend and decreased after VTC process. Furthermore, the degree of densification had a minor effect on the wettability.     

Evaluation of Methods Used for the Analysis of Volatile Organic Compounds of Sugarcane (Cachaça) and Fruit Spirits

Sugarcane spirits are defined as beverages with an alcohol content ranging from 38 to 54 % v/v at 20 °C, obtained from the simple alcoholic distillation of sugarcane or fermented sugarcane must. Fruit spirits may be obtained directly from fruit or from fruit must that may or may not contain seeds by distillation, and present specific organoleptic characteristics and an alcohol content of 36 to 54 % v/v at 20 °C. The physicochemical and sensory qualities of these beverages are dependent on the nature and quality of the raw materials, fermentation, distillation and aging, and are organoleptically characterised by the presence of volatile organic compounds (VOC) (organic acids, aldehydes, esters, higher alcohols, terpenes, lactones and others). This paper presents studies performed to evaluate VOC in spirits. Among the volumetric and instrumental methods described to evaluate VOC in spirits, chromatographic methods are the most cited. Chromatographic techniques employed include high performance liquid chromatography, gas chromatography with flame ionisation detection, gas chromatography with mass spectrometric detection and two-dimensional gas chromatography with time-of-flight mass spectrometry.     

Substrate specificity of glutamyl endopeptidase (GE): Hydrolysis studies with a bovine α-casein preparation

Glutamyl endopeptidase (GE) from Alcalase™ 2.4 L was purified using hydrophobic interaction (HIC) and ion-exchange (IEX) chromatography. The yield of GE obtained was approximately 42%. Bovine α-casein (containing α_s1- and α_s2-casein) was digested with GE at 37 and 50 °C for 4 h. Samples were withdrawn at various time intervals and the peptides generated were analysed using mass spectrometry. GE activity was highly specific and hydrolysed the peptide bond predominantly on the carboxy side of Glu residues while hydrolysis on the carboxyl side of Asp residues was also observed. Hydrolysis did not occur when Pro was at the P₁′ position. In Glu-Glu-X (X = Arg, Asn, Ile and Ser) and Glu-Glu-Glu-Lys sequences, hydrolysis of Glu-X and Glu-Lys was preferred. The results are relevant to our understanding of the hydrolytic specificity of Alcalase, a food-grade proteolytic preparation containing GE activity which is used in the generation of casein hydrolysates.     

Development and evaluation of a Mycobacterium bovis interferon-γ enzyme-linked immunospot (ELISpot) assay for detection of bovine tuberculosis

Bovine tuberculosis (bTB) caused by Mycobacterium bovis is an important zoonotic disease. This infection is difficult to control because of the limited ability of the tuberculin skin test (TST) and ancillary IFN-γ release assay to detect all infected animals. In this study, we aimed to develop an efficient assay based on the enzyme-linked immunospot (ELISpot) technique for the diagnosis of bTB, with IFN-γ monoclonal antibodies 3E9 and Bio-labeled 6F8 used as capture and detection antibodies, respectively. As expected, there were significantly more M. bovis-specific spot-forming units (SFU) in bTB-infected cattle than in healthy cattle when an M. bovis-specific antigen, CFP-10-ESAT-6 fusion protein (CE protein), was used. The M. bovis IFN-γ ELISpot assay demonstrated a high level of agreement (90.83%) with the BOVIGAM ELISA test (Thermo Fisher Scientific) for detecting bTB. Furthermore, 3 of 109 cattle tested negative by both the TST and the BOVIGAM ELISA tests, but positive by the ELISpot assay (TST^? ELISA^? ELISpot⁺). During subsequent long-term monitoring, these 3 cattle became TST⁺ ELISA⁺ ELISpot⁺. These results suggest that the M. bovis IFN-γ ELISpot assay we established could detect infected cattle earlier than the BOVIGAM ELISA test.     

Phages of Bacteroides (GB-124): a novel tool for viral waterborne disease control?

Current fecal indicator bacteria (FIB) and emerging microbial source tracking (MST) methods may indicate the presence and even the likely source of water contamination, but they are less effective at determining the potential risk to health from human enteric viruses. This paper investigates the presence of human-specific phages (detected using a low-cost MST method) in municipal wastewaters (MW) and assesses whether they may be used effectively to screen for the likely presence of human adenovirus (HAdV) and norovirus (NoV). The findings demonstrated that all samples positive for HAdV and/or NoV also contained phages infecting Bacteroides GB-124 (mean = 4.36 log(10) PFU/100 mL) and that GB-124 phages, HAdV, and NoV were absent from samples of nonhuman origin. HAdV and NoV were detected more frequently in MW samples containing higher levels of phages (e.g., >10(2)) and FIB (e.g., >10(3)). Interestingly, at one sewage treatment works (STW), the levels of GB-124 phages present in treated MW were not significantly lower (p = 0.001) than those in untreated MW. There was a positive correlation (R = 0.42) between the size of STW and the number of GB-124 phages present in the final treated effluent. Therefore, the detection of GB-124 phages by a simple phage-lysis method may have considerable potential as a low-cost surrogate for the detection of certain human pathogenic viruses in MW and receiving waters.     

Analysis of urban consumers’ willingness to pay a premium for African Leafy Vegetables (ALVs) in Kenya: a case of Eldoret Town

This study surveyed urban consumers in Eldoret Town, Kenya to determine the willingness to pay (WTP) a premium for African leafy vegetables (ALVs) and the underlying determinants using the semi-double bounded contingent valuation choice and logit models, respectively. Consumers generally preferred ALVs to exotic leafy vegetables and were willing to pay an average premium of 79 % for them: 88 % and 70 % in open air and supermarkets, respectively. The WTP premium was positively influenced by age, presence of children in the household, years of schooling of the household decision maker and the number of years the consumers had been consuming ALVs. Implications for policy are drawn.     

Nutritional properties and phenolic content of a bakery product substituted with a mango (Mangifera indica) ‘Ataulfo’ processing by-product

Wheat flour and cane sugar were partially substituted (50 and 75%) by a mango-processing by-product (MPB) as an added-value food ingredient in muffins. Their sensory analysis, chemical composition, antioxidant activity and in vitro starch hydrolysis properties were studied. Sensory analysis showed statistically significant difference (p < 0.05) between control and muffins 75% MPB substituted level (p < 0.05) with the highest score. Proximate analysis revealed that muffins substituted with MPB had significantly (p < 0.05) higher moisture, ash, soluble, insoluble and total indigestible fraction contents but lower total soluble carbohydrates and available starch contents than a non-substituted (control) muffin. Total soluble polyphenol (TSP) content increased about three times (from 1.86 to 5.36 g GAE/100 g dw) with MPB substitution. Chlorogenic, caffeic, gallic, hydroxycinnamic and ferulic acids were identified as major TSP. Muffins with MPB, exhibited better antioxidant properties (104.0 to 108.5 μmol TE/g dw for DPPH assay and 34.1 to 19.1 mmol TE/g dw for FRAP assay) than the control formulation. The presence of high phenolic and insoluble indigestible fraction contents, which may be responsible of the lower rate of starch hydrolysis observed in muffins prepared with MPB, might modulate the postprandial glucose response in vivo. MPB may be used as an ingredient in foods with add-value with potential health-promoting features, besides providing a solution to the environmental problems associated with the disposal of mango by-products.     

Interactions of starch with a cyanidin–catechin pigment (vignacyanidin) isolated from Vigna angularis bean

A cyanidin–catechin pigment isolated from adzuki bean (vignacyanidin) interacted with starch. The pigment had absorption maxima at 530 and 540 nm at pH 2.0 and 6.8, respectively, and starch (10 and 100 mg ml⁻¹) increased the absorbance, shifting the absorption maxima to longer wavelengths. Nitrite oxidised vignacyanidin at pH 2.0, and the oxidation resulted in the production of nitric oxide (NO). Rates of the oxidation and the NO production were enhanced by starch. Vignacyanidin inhibited α-amylase-catalysed digestion of starch at pH 6.8, and amylose digestion was more effectively inhibited than amylopectin digestion. The above results suggest (i) that binding of the pigment to starch increased the accessibility of nitrous acid to the pigment, and (ii) that the binding reduced the digestibility of starch by α-amylase. Possible functions of the pigment in the stomach and the intestine are postulated, taking the above results into account.