Influence of processing on the levels of amines and proline and on the physico-chemical characteristics of concentrated orange juice

The influence of processing on the levels of bioactive amines and proline as well as on some physico-chemical characteristics of concentrated orange juice was investigated. Samples were collected at seven points of a production line on three non-consecutive days, and analysed for the levels of 12 bioactive amines, proline, and reducing and non-reducing sugars, and for some physico-chemical characteristics. Among the amines analysed, only putrescine, spermidine and synephrine were found in the samples at all processing stages. Significant differences were observed for spermidine and total amine levels throughout processing. Synephrine and putrescine were resistant to processing. Proline levels changed significantly throughout processing, as did levels of reducing and non-reducing sugars. The pH varied from 3.59 to 3.72, acidity from 0.873 to 0.918 g citric acid/100 mL, and density from 1.0378 to 1.0970 g/mL. Among these parameters, pH, acidity and density were significantly affected by processing.     

Chemistry of gluten proteins

Gluten proteins play a key role in determining the unique baking quality of wheat by conferring water absorption capacity, cohesivity, viscosity and elasticity on dough. Gluten proteins can be divided into two main fractions according to their solubility in aqueous alcohols: the soluble gliadins and the insoluble glutenins. Both fractions consist of numerous, partially closely related protein components characterized by high glutamine and proline contents. Gliadins are mainly monomeric proteins with molecular weights (MWs) around 28,000-55,000 and can be classified according to their different primary structures into the alpha/beta-, gamma- and omega-type. Disulphide bonds are either absent or present as intrachain crosslinks. The glutenin fraction comprises aggregated proteins linked by interchain disulphide bonds; they have a varying size ranging from about 500,000 to more than 10 million. After reduction of disulphide bonds, the resulting glutenin subunits show a solubility in aqueous alcohols similar to gliadins. Based on primary structure, glutenin subunits have been divided into the high-molecular-weight (HMW) subunits (MW=67,000-88,000) and low-molecular-weight (LMW) subunits (MW=32,000-35,000). Each gluten protein type consists or two or three different structural domains; one of them contains unique repetitive sequences rich in glutamine and proline. Native glutenins are composed of a backbone formed by HMW subunit polymers and of LMW subunit polymers branched off from HMW subunits. Non-covalent bonds such as hydrogen bonds, ionic bonds and hydrophobic bonds are important for the aggregation of gliadins and glutenins and implicate structure and physical properties of dough.     

L－脯氨酸产生菌的选育

以嗜乙酰乙酸棒杆菌ＡＴＣＣｌ３８７０为出发菌株，经硫酸二乙酯（ＤＥＳ）和亚硝基胍（ＮＴＧ）逐级诱变处理，结构类似物定向选育，获得一株Ｌ－脯氨酸高产菌ＺＱ－３（ＳＧｒ、Ｓｕｃｇ、ＤＨＰｒ）。在含１６％葡萄糖的培养基中，摇瓶发酵７２ｈ，产酸率为５．３％～５．５％。     

聚合物微球支载L-脯氨酸磺酰胺的合成

以L-羟脯氨酸为手性原料,经过O-烷基化、氨化、磺酰化,制备L-脯氨酸磺酰胺手性单体,在AIBN引发下,与苯乙烯和二乙烯基苯溶液聚合制备了聚苯乙烯微球支载的L-脯氨酸磺酰胺化合物,用IR,1H NMR,13C NMR及元素分析对其进行表征,其支载容量为0.70 mmol/g,总产率27.66%,所得结果与其结构相吻合。     

Contribution of amino acids to strawberry fruit quality and their relevance as stress indicators under NaCl salinity

Strawberry cvs Korona and Elsanta, differing in their sensitivity to salt stress, were exposed to 0, 40, or 80 mM NaCl in the root medium from the end of April to mid-August. Although fruits of both cultivars contained comparable amounts of Na⁺ and Cl⁻, fruit quality was more impaired in cv. Elsanta, as indicated by the larger reductions of fruit size and sugar/acid ratios. Malondialdehyde levels started to rise significantly at 40 mM NaCl in the more sensitive cv. Elsanta, but at 80 mM in cv. Korona. Total amino acid levels, especially contents of essential amino acids, rose significantly in both cvs. Salt stress also increased contents of free proline, asparagine, and glutamine. Their increases may contribute to osmotic adjustment. The results of the present study favour the interpretation that elevated levels of proline, asparagine and glutamine are indicative of salt stress damage.     

印度梨形孢诱导烟草的抗病性分析

内生真菌印度梨形孢(Piriformospora indica)能够增强植物体抗生物和非生物胁迫能力.为了明确印度梨形孢对诱导烟草抗病性的作用,分别进行了接种病原菌长柄链格孢、胶孢炭疽菌、终极腐霉和茄丝核菌后印度梨形孢定殖的烟草对赤星病、炭疽病、猝倒病和立枯病害的抗性试验,同时分析了接种长柄链格孢后烟叶中丙二醛(MDA)和脯氨酸(Pro)含量、抗氧化酶活性以及病程相关蛋白基因表达水平.结果表明:印度梨形孢定殖的烟草,接种长柄链格孢后,烟叶病斑显著减小,烟叶中MDA含量显著降低,Pro含量显著升高,病程相关蛋白基因PR-1a,PR2,PR3和PR5的表达量明显提高;接种胶孢炭疽菌后,烟叶病斑减小;终极腐霉和茄丝核菌对烟草的危害症状显著减轻.印度梨形孢能诱导烟草产生抗病性,是通过维持生物膜系统的完整性、稳定细胞内渗透压以及膜脂过氧化在较低水平、并调控病程相关蛋白基因的表达来实现的.     

Characterization of Male and Female Jojoba Plants Employing Antioxidants,Lipid Peroxidation and Physiological Studies

Jojoba, [Simmondsia chinensis (Link) Schneider] is a commercially important dioecious, desert shrub which is mainly cultivated for liquid wax (oil) present in its seeds (40–60 %). The oil is being utilized by the cosmetic, pharmaceuticals, and other industries for certain formulations. In this study, gender based differences in biochemical and physiological parameters were examined in relation to natural drought conditions. The amount of protein, proline, cysteine, chlorophyll a and b, carotenoids and enzymatic activities were evaluated in leaves of male and female Jojoba genotypes. Significant differences between genders were found which was attributed to higher drought tolerance of males than females. Males showed higher contents of protein (113.05 ± 0.88 mg g^?1 FW), proline (95.13 ± 2.33 µmol g^?1 FW), cysteine (42.47 ± 2.69 µmol g^?1 FW) than females (proteins: 70.77 ± 0.52 mg g^?1 FW, proline: 66.61 ± 1.75 µmol g^?1 FW, cysteine: 17.84 ± 3.00 µmol g^?1 FW). Malondialdehyde (MDA) content was lower in male genotypes (18.29 ± 0.53 µmol g^?1 FW) than female genotypes (23.02 ± 0.70 µmol g^?1 FW). Higher activities of catalase (CAT) [0.088 ± 0.005 nkat mg^?1 protein], guaiacol peroxidase (GPX) [0.006 ± 0.001 nkat mg^?1 protein], glutathione reductase (GR) [9.02 ± 0.04 nkat mg^?1 protein], ascorbate peroxidase (APX) [4.28 ± 0.08 nkat mg^?1 protein] and superoxide dismutase (SOD) [151.75 ± 3.58 nkat mg^?1 protein] were found in males compared to females [CAT: 0.007 ± 00 nkat mg^?1 protein, GPX: 0.003 ± 00 nkat mg^?1 protein, GR: 6.40 ± 0.06 nkat mg^?1 protein, APX: 3.08 ± 0.06 nkat mg^?1 protein, SOD: 52.51 ± 1.73 nkat mg^?1 protein]. Chlorophyll b content was also higher in males than females.     

Inhibition of dipeptidyl peptidase IV (DPP-IV) by proline containing casein-derived peptides

Dipeptides with a C terminal Pro inhibit dipeptidyl peptidase IV (DPP-IV), a key enzyme in incretin hormone processing. It was hypothesised that tri- and tetrapeptides with a proline at the C-terminus may also be DPP-IV inhibitors. Therefore, an in silico hydrolysis approach was used to release short (4 ? amino acids) C terminal Pro peptides from the individual caseins which constitute Pro rich substrates. This was achieved using theoretical digestion of caseins with a prolyl oligopeptidase activity. Fifteen peptides were subsequently selected for in vitro DPP-IV inhibitory analysis. Stability of these peptides to gastrointestinal enzymes was also evaluated in silico and the predicted breakdown peptides were assessed for their DPP-IV inhibitory and antioxidant potential. New DPP-IV inhibitors were identified, the most potent being Phe-Leu-Gln-Pro (IC₅₀ 65.3 ± 3.5 μM). A low in vitro antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging) activity was also associated with the peptides studied. The strategy presented highlights the utility of employing an in silico approach for the prediction of food-derived peptides with a potential role in glycaemic management for subsequent development of functional foods.     

Toward the biomimetic implant surface: Biopolymers on titanium-based implants for bone regeneration

Replacing malfunctioning tissues with titanium-based implants has become a widespread practice spurred by population aging. Advances in biomaterials, technology and implantation protocols have led to increasing expectations on the applicability and durability of implants. The field has recently moved from a bioinert to a bioactive paradigm due to surface modifications that trigger specific responses on the surrounding tissues. Biopolymeric surface coatings have taken up a central role in these developments. The use of these and other biomimetic strategies on implants provides greater control over material–cell interactions and it is aimed at improving long-term clinical results by replicating some of the structures and mechanisms of living tissues. This review summarizes the state of the art of biomimetic implants and discusses the main directions and challenges of this field toward a more predictable and successful implant osseointegration.