Effect of microwave and hot air treatment on enzyme activity, oil fraction quality and antioxidant activity of wheat germ.

The aim of this work was to study the effects of microwaves (MW) and hot air (HA) treatments on enzyme activities and quality parameters in wheat germ (WG). Both MW and HA were effective at inactivating lipases. MW treatment inactivated lipases more at lower temperatures (60 and 70 °C) than HA (150-200 °C). Peroxide values, acidity, and fatty acid profiles of WG oil remained unaltered after HA and MW treatments. Loss of α-tocopherol contents was observed following HA treatment, but total tocopherol content remained above 77% baselines values in all treated samples. The main antioxidant mechanism of WG extracts was associated with inactivation of radicals, rather than reducing capacity. MW treatment at 60 and 70 °C enhanced radical scavenging activity, while total polyphenol contents and reducing capacities were negatively affected. Therefore, MW treatment is a promising technology to stabilise WG, retaining quality and antioxidant activity.

Effects of low-temperature microwave treatment of wheat germ.

BACKGROUND: Wheat germ has a great potential byproduct in food formulations for its outstanding nutritional value. To allow valorization, there is a need to inactivate endogenous enzymes such as lipases to avoid lipid oxidation. In the present study, the effects of microwaves on enzyme activity, as well as on functional and physical properties of wheat germ, were evaluated. Microwave treatments were performed at 50, 60 and 70 °C for 5-20 min. RESULTS: Lipase activity was severely affected at 60 and 70 °C in contrast to lipoxygenase. Microwave treatment did not cause changes in germ moisture content or color parameters. No significant changes were observed in equilibrium moisture content when comparing the adsorption and desorption processes of raw and microwave-treated wheat germ. The best model to describe sorption process was the Guggenheim-Anderson-De Boer equation. According to the dielectric properties of raw wheat germ, it could be considered as transparent to energy (ε' < 1.87 and ε'' < 0.35). Thermal analysis of proteins showed a low denaturation degree (below 35% to raw material). In addition, some functional properties were enhanced such as oil retention capacity. Conformational changes as a result of microwave treatment were associated with the slight decline observed on the monolayer moisture content. CONCLUSION: Microwave treatments of wheat germ at 60 and 70 °C were effective for lipase inactivation. Physical properties did not change drastically after the treatments. Microwave-treated wheat germ could be a good source of high-protein ingredient in food product development. © 2021 Society of Chemical Industry.

The Tissue Architecture of Oral Squamous Cell Carcinoma Visualized by Staining Patterns of Wheat Germ Agglutinin and Structural Proteins Using Confocal Microscopy.

OBJECTIVES: Tissue architecture and cell morphology suffer profound alterations during oral cancer and are important markers for its progression and outcome. For precise visualization of tissue architecture in oral cancer, we used confocal microscopy to examine the staining pattern of wheat germ agglutinin, a lectin that binds membrane glycoproteins, and the staining patterns of structural proteins. MATERIALS AND METHODS: Paraffin sections of oral squamous cell carcinoma were stained with fluorescently labeled wheat germ agglutinin and with antibodies against structural proteins, which were revealed by immunohistochemistry with tyramide signal amplification. RESULTS: Membrane localization of wheat germ agglutinin was markedly decreased in the basal layers and in regions of tumor invasion, accompanied by cytoplasmic redistribution of E-cadherin, ß-actin and syndecan-1. Wheat germ agglutinin staining clearly identified tumor clusters within the surrounding stroma, and tumor cells with elongated morphology. CONCLUSIONS: Our results suggest that the wheat germ agglutinin staining pattern is indicative of the degree of cell cohesion in oral squamous cell carcinoma, which decreases in basal layers and invasive tumor clusters with more migratory morphologies. Wheat germ agglutinin staining in combination with confocal microscopy could constitute, therefore, a valuable tool for the study of tissue architecture in oral cancer.

Physico-chemical characterization of protein fraction from stabilized wheat germ.

Wheat germ shows the highest nutritional value of the kernel. It is highly susceptible to rancidity due to high content of unsaturated fat and presence of oxidative and hydrolytic enzymes. In order to improve its shelf life, it is necessary to inactivate these enzymes by a thermal process. In this work the functional properties and some characteristics of the protein fraction of treated wheat germ were evaluated. Sequential extraction of proteins showed loss of protein solubility and formation of aggregates after heating. DSC thermograms showed that wheat germ treated for 20 min at 175 °C reached a protein denaturation degree of ~ 77%. The stabilization process of wheat germ affected significantly some functional properties, such as foaming stability and protein solubility at pH 2 and pH 8. Nevertheless, heating did not affect the water holding, oil holding and foaming capacity of protein isolates.

Wheat germ stabilization by infrared radiation.

Wheat germ has an important enzymatic activity, being lipases the enzymes which cause the highest impact in the reduction of shelf life. The objective of this study was to evaluate the effects of infrared radiation on wheat germ stabilization in an attempt to extend the shelf life. The effects of treatment time, gap (sample distance to IR emitters) and infrared radiation intensity on wheat germ were analyzed through response surface methodology. Final moisture content, final temperature, color of germ and germ oil quality parameters: free fatty acid content changes and total tocopherol content were the responses evaluated using a Box-Behnken design. A combination of an infrared radiation intensity of 4800 W/m2, a 3 min treatment and 0.2 m emitter-sample distance were the best processing condition to stabilize the wheat germ without significantly reduction of the tocopherol content. A confirmatory experiment was conducted with these optimal conditions, and the heat-treated and raw germ samples were stored for 90 days at room temperature in three layer packages to protect them against light and oxygen. The oil quality parameters indicated that the raw germ had a shelf-life of about 15 days, with the heat-treated wheat germ maintaining its quality for at least 90 days under these stored conditions.

Affinity chromatography matrices for depletion and purification of casein glycomacropeptide from bovine whey.

Casein glycomacropeptide (CMP) is a 64- amino acid peptide found in cheese whey, which is released after κ-casein specific cleavage by chymosin. CMP lacks aromatic amino acids, a characteristic that makes it usable as a nutritional supplement for people with phenylketonuria. CMP consists of two nonglycosylated isoforms (aCMP A and aCMP B) and its different glycosylated forms (gCMP A and gCMP B). The most predominant carbohydrate of gCMP is N-acetylneuraminic acid (sialic acid). Here, we developed a CMP purification process based on the affinity of sialic acid for wheat germ agglutinin (WGA). After formation of chitosan beads and adsorption of WGA, the agglutinin was covalently attached with glutaraldehyde. Two matrices with different WGA density were assayed for CMP adsorption. Maximum adsorption capacities were calculated according to the Langmuir model from adsorption isotherms developed at pH 7.0, being 137.0 mg/g for the matrix with the best performance. In CMP reduction from whey, maximum removal percentage was 79% (specifically 33.7% of gCMP A and B, 75.8% of aCMP A, and 93.9% of aCMP B). The CMP was recovered as an aggregate with an overall yield of 64%. Therefore, the matrices developed are promising for CMP purification from cheese whey. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:171-180, 2017.

N-acetyl Glucosamine Distribution and Mitochondrial Activity of Tumor Cell Exposed to Photodynamic Therapy.

The use of lectins can play an important role for tracking modification on cell surface components, since lectins can be easily complexed with radioisotopes, biotin or fluorescein, facilitating the evaluation of carbohydrates distribution in the cell and mitochondrial activity. The aim of this study was to evaluate photodynamic therapy effects on indirect distribution of N-acetyl-glucosamine terminal glycoproteins, in human laryngeal carcinoma HEp-2 cell line surface, using lectin wheat germ agglutinin (WGA) and on mitochondrial activity, for the same cell line, using MitoTracker. The photosensitizer Aluminum Phthalocyanine Tetrasulfonate (AlPcS4) was administrated at 10 µM/mL, followed by an incubation period for its accumulation in the tumor cells, which were irradiated with laser diode λ = 685 nm and energy density of 4.5 J/cm2. Our results indicated that, after Photodynamic Therapy (PDT), it was observed N-acetyl glucosamine terminal glycoprotein expression and mitochondrial O2 production, compared to the control group. Based on these results, we suggest that PDT influences the O2 mitochondrial production and the presence of surface glycoproteins N-acetyl glucosamine terminals.

The brainstem localization of gastric preganglionic parasympathetic neurons in the Agouti (Dasyprocta leporina) / Localización del tronco encefálico de las neuronas parasimpáticas preganglionares gástricas en el agutí (Dasyprocta leporina)

This study was designed to determine qualitatively, the source of gastric vagal nerve fibres in the Agouti. A total of 18 male and female adult agoutis were used for the present investigation. Following anaesthesia, laparotomy was performed and the stomach exteriorized. Multiple intramuscular injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) were then made into different areas of the stomach in the experimental animals. The control animals were divided into four groups of two animals each. The first group had intraperitoneal injection of the tracer, the second had intramuscular injection of normal saline, the third group had injection of tracer into the hepatic portal vein and the last group had injection of the tracer into the gastric walls followed immediately by bilateral vagotomy. Following a survival period offive to seven days, the animals were sacrificed by transcardial perfusion, first with normal saline followed by fixative and finally with 20% buffered sucrose. Following perfusion, the brainstem was extracted from the brain, immersed in 20% buffered sucrose and kept refrigerated overnight for cryoprotection. The brainstems were subsequently sectioned serially, processed for WGA-HRP neurohistochemistry and then analysed under light and dark-field illuminations. The analysis of the sections taken from the experimental animals revealed bilateral presence of WGA-HRP labelled neurons in the dorsal motor nucleus of the vagus nerve (DMNV) and the nucleus ambiguus (nA) of the medulla oblongata. No labelled neurons were seen in any of the sections taken from the control animals. The implications of the findings are discussed.

Este estudio fue diseñado para determinar cualitativamente el origen de las fibras gástricas del nervio vago en el agutí. Un total de 18 agutíes adultos masculinos y femeninos fueron utilizados para la presente investigación. Después de la anestesia, se realizó una laparotomía y se sacó el estómago al exterior. Luego se hicieron múltiples inyecciones intramusculares de aglutinina de germen de trigo con peroxidasa de rábano (WGA-HRP) en diferentes áreas del estómago de los animales experimentales. Los animales del control fueron divididos en cuatro grupos de dos animales cada uno. Al primer grupo se le puso una inyección intraperitoneal del marcador; al segundo se le administró una inyección intramuscular de solución salina normal; al tercer grupo se le inyectó el marcador en la vena porta hepática; y al último grupo se le puso la inyección del marcador en las paredes gástricas, seguida inmediatamente por una vagotomía bilateral. Tras un periodo de supervivencia de cinco a siete días, los animales fueron sacrificados por perfusión transcardíaca, primero con solución salina normal, seguida de fijador, y finalmente con sacarosa tamponada al 20%. Después de la perfusión, el tronco encefálico fue extraído del cerebro, inmerso en sacarosa tamponada al 20%, y mantenido en refrigeración durante la noche para su crioprotección. Los tronos encefálicos fueron luego seccionados en serie, procesados para para el análisis neuro-histoquímico mediante aglutinina de germen de trigo con peroxidasa de rábano, y analizados entonces bajo iluminaciones de campo de luz y campo oscuro. El análisis de las secciones tomadas de animales experimentales reveló la presencia bilateral de neuronas etiquetadas WGA-HRP en el núcleo motor dorsal del nervio vago (DMNV) y en el núcleo ambiguo (nA) de la médula oblonga. No se observaron neuronas etiquetadas en ninguna de las secciones tomadas de los animales de control. Se discuten las implicaciones de los hallazgos.

Efficient wheat germ agglutinin purification with a chitosan-based affinity chromatographic matrix.

An efficient affinity chromatographic matrix based on chitosan for wheat germ agglutinin (WGA) purification was developed. The matrices assayed consisted of chitosan mini-spheres cross-linked with epichlorhydrin 45, 250 or 500 mM. The maximum adsorption capacity of pure WGA - calculated from the corresponding isotherms - was between 43.2 and 48.9 mg/g at pH 5.0 and between 16.6 and 27.6 mg/g at pH 8.5. However, the adsorption of agglutinin from wheat germ extract was higher at pH 8.5. In addition, 0.5 g of mini-spheres cross-linked with epichlorhydrin 250 mM adsorbed 94.5% of the WGA present in 5 mL of the concentrated extract. Acetic acid was able to elute 100% of the adsorbed WGA. The purity of the WGA obtained was greater than 95% and the purification factor was 56.8. The matrix was able to maintain an efficient performance of the purification process for three consecutive cycles. A new method to monitor the purification process by RP-HPLC was developed.