Grape and wine analysis: Oenologists to exploit advanced test kits.
Charnock, S. C. & McCleary, B. V. (2005). Revue des Enology, 117, 1-5.
It is without doubt that testing plays a pivotal role throughout the whole of the vinification process. To produce the best possible quality wine and to minimise process problems such as “stuck” fermentation or troublesome infections, it is now recognised that if possible testing should begin prior to harvesting of the grapes and continue through to bottling. Traditional methods of wine analysis are often expensive, time consuming, require either elaborate equipment or specialist expertise and frequently lack accuracy. However, enzymatic bio-analysis enables the accurate measurement of the vast majority of analytes of interest to the wine maker, using just one piece of apparatus, the spectrophotometer (see previous issue No. 116 for a detailed technical review). Grape juice and wine are amenable to enzymatic testing as being liquids they are homogenous, easy to manipulate, and can generally be analysed without any sample preparation.
Megazyme “advanced” wine test kits general characteristics and validation.
Charnock, S. J., McCleary, B. V., Daverede, C. & Gallant, P. (2006). Reveue des Oenologues, 120, 1-5.
Many of the enzymatic test kits are official methods of prestigious organisations such as the Association of Official Analytical Chemicals (AOAC) and the American Association of Cereal Chemists (AACC) in response to the interest from oenologists. Megazyme decided to use its long history of enzymatic bio-analysis to make a significant contribution to the wine industry, by the development of a range of advanced enzymatic test kits. This task has now been successfully completed through the strategic and comprehensive process of identifying limitations of existing enzymatic bio-analysis test kits where they occurred, and then using advanced techniques, such as molecular biology (photo 1), to rapidly overcome them. Novel test kits have also been developed for analytes of emerging interest to the oenologist, such as yeast available nitrogen (YAN; see pages 2-3 of issue 117 article), or where previously enzymes were simply either not available, or were too expensive to employ, such as for D-mannitol analysis.
Bioactive compounds from endemic plants of Southwest Portugal: Inhibition of acetylcholinesterase and radical scavenging activities.
Tavares, L., Fortalezas, S., Tyagi, M., Barata, D., Serra, A. T., Martins Duarte, C. M. M., Duarte, R. O., Felicano, R. P., Bronze, M. R., Espírito-Santo, M. D., Ferreira, R. B. & Santos, C. N. (2012). Pharmaceutical Biology, 50(2), 239-246.
Context: Natural products are reported to have substantial neuroprotective activity due to their radical scavenging capacity, and also acetylcholinesterase (AChE) inhibitory capacity, both activities important in neurodegeneration.
Objective: The undesirable side effects of compounds in pharmacological use make it important to identify natural neuroprotective molecules. This work assesses the potential of five endemic Portuguese plants as sources of neuroprotective compounds.
Materials and methods: Antioxidant capacity for peroxyl radical was determined by Oxygen Radical Absorbance Capacity method and for hydroxyl by Electron Paramagnetic Resonance, as well as AChE inhibitory capacity of the plant hydroethanolic extracts. The molecules responsible for these valuable properties were also tentatively identified by HPLC.
Results and discussion: Armeria rouyana and Thymus capitellatus presented some of the highest phenolic contents (76.60 ± 7.19 and 12.82 ± 0.24 mg GAE g-1 dw, respectively) and antioxidant capacities (592 ± 116 and 449 ± 57 μmol TE g-1 dw, respectively). The flavonoids were identified as the phytomolecules related to the antioxidant capacity of these plant extracts; in the case of A. rouyana, L-ascorbic acid also made an important contribution (3.27 ± 0.26 mg g-1 dw). Plant extracts clearly demonstrated effective AChE inhibitory activity (480 ± 98 and 490 ± 46 μg mL-1, respectively), that could be associated to polyphenols.
Conclusions: The extracts of A. rouyana and T. capitellatus and their active components, especially polyphenols, demonstrate interesting neuroprotective potential. They, therefore, deserve further study as their phytomolecules are promising sources of either natural neuroprotective products and/or novel lead compounds.
Effect of 1-MCP on quality and antioxidant capacity of in vitro digests from ‘Sunrise’ apples stored at different temperatures.
Qiu, S., Lu, C., Li, X. & Toivonen, P. (2009). Food Research International, 42(3), 337-342.
The antioxidant capacities of phenolic and non-phenolic fractions for in vitro digestates from ‘Sunrise’ apple were assessed after postharvest application of 1-methylcyclopropene (1-MCP), a ripening inhibitor, and three weeks storage at 5, 13, 15, 18 and 22°C. An in vitro digestion system was used to generate the soluble bioaccessable digestate which was then fractionated into phenolic and non-phenolic fractions. The two fractions were assayed for Folin-Ciocalteu Reaction (FCR) reducing capacity and peroxyl radical scavenging capacity. Quality retention of the fruit was assessed by measuring internal ethylene concentration, firmness and titratable acidity. Treatment with 1-MCP inhibited internal ethylene concentration and better maintained the firmness and titratable acidity of ‘Sunrise’ summer apples as compared with untreated control apples at storage temperatures of 15°C and above. The FCR reducing capacity of the phenolic fraction of the in vitro, simulated gastrointestinal digestates showed similar response as did the quality measures, with significantly higher activity in the 1-MCP treated fruit at higher storage temperatures. However, no consistent differences were found between 1-MCP and control treatments for the FCR reducing capacity of the non-phenolic fraction or for the peroxyl radical scavenging capacity of either fraction. The non-phenolic fractions consistently had higher levels of both types of antioxidant capacities. Treatment and storage of ‘Sunrise’ apples at elevated temperatures (> 13°C) resulted in improved fruit quality and retention of reducing capacity in simulated gastrointestinal digestates.
Influence of starter cultures on the antioxidant activity of kombucha beverage.
Malbaša, R. V., Lončar, E. S., Vitas, J. S. & Čanadanović-Brunet, J. M. (2011). Food Chemistry, 127(4), 1727-1731.
This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28°C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.
Antioxidant capacity of Macaronesian traditional medicinal plants.
Tavares, L., Carrilho, D., Tyagi, M., Barata, D., Serra, A. T., Duarte, C. M. M. , Duarte, R. O., Feliciano, R. P., Bronze, M. R., Chicau, P., Espírito-Santo, M. D., Ferreira, R. B. & Dos Santos, C. N. (2010). Molecules, 15(4), 2576-2592.
The use of many traditional medicinal plants is often hampered by the absence of a proper biochemical characterization, essential to identify the bioactive compounds present. The leaves from five species endemic to the Macaronesian islands with recognized ethnobotanical applications were analysed: Apollonias barbujana (Cav.) Bornm., Ocotea foetens (Ainton) Baill, Prunus azorica (Mouill.) Rivas-Mart., Lousã, Fern. Prieto, E. Días, J. C. Costa & C. Aguiar,
Rumex maderensis Lowe and Plantago arborescens Poir. subsp. maderensis (Dcne.) A. Hans. et Kunk. Since oxidative stress is a common feature of most diseases traditionally treated by these plants, it is important to assess their antioxidant capacity and determine the molecules responsible for this capacity. In this study, the antioxidant capacity of these plants against two of the most important reactive species in human body (hydroxyl and peroxyl radicals) was determined. To trace the antioxidant origin total phenol and flavonoid contents as well as the polyphenolic profile and the amount of trace elements were determined. There was a wide variation among the species analysed in what concerns their total leaf phenol and flavonoid contents. From the High Performance Liquid Chromatography (HPLC) electrochemically detected peaks it was possible to attribute to flavonoids the antioxidant capacity detected in A. barbujana, O. foetens, R. maderensis and P. azorica extracts. These potential reactive flavonoids were identified for A. barbujana, R. maderensis and P. azorica. For R. maderensis a high content (7 mg g-1 dry weight) of L-ascorbic acid, an already described antioxidant phytomolecule, was found. A high content in selenomethionine (414.35 μg g-1 dry weight) was obtained for P. ar borescens subsp. maderensis extract. This selenocompound is already described as a hydroxyl radical scavenger is reported in this work as also possessing peroxyl radical scavenging capacity. This work is a good illustration of different phytomolecules (flavonoids, organic acids and selenocompounds), presents in leaves of the five traditional medicinal plants endemic to Macaronesia, all exhibiting antioxidant properties.
Nutritional and sensory quality during refrigerated storage of fresh-cut mints (Mentha x piperita and M. spicata).
Curutchet, A., Dellacassa, E., Ringuelet, J. A., Chaves, A. R. & Viña, S. Z. (2014). Food Chemistry, 143, 231-238.
The effect of storage time on quality attributes of refrigerated fresh-cut mints (Mentha × piperita and M. spicata) was studied. Atmosphere composition, respiratory activity, weight loss, surface colour, total chlorophyll, carotenoids, browning potential, total phenols, flavonoids, radical-scavenging activity, ascorbic acid and essential oil yield and composition were analysed. Respiratory activity of peppermint and spearmint samples diminished moderately (42% and 28%, respectively) after 21 days at 0°C. A slight modification of the internal atmosphere was achieved. Surface colour, chlorophyll, carotenoid and antioxidant compounds remained almost constant. The yield of essential oil did not change or it showed an apparent increase after 21 days at 0°C, depending on plant growth stage. The characteristic flavour components of peppermint (menthone and menthol) increased, while the contents of the main constituents of spearmint essential oil showed minor variations after storage. The conditions assayed for packaging and storing fresh-cut mints were adequate to achieve a relatively long shelf life and they retained their antioxidant properties.
A high‐grain protein content locus on barley (Hordeum vulgare) chromosome 6 is associated with increased flag leaf proteolysis and nitrogen remobilization.
Jukanti, A. K. & Fischer, A. M. (2008). Physiologia Plantarum, 132(4), 426-439.
Leaf senescence and nitrogen remobilization from senescing tissues are two important factors determining grain protein content (GPC) in cereals. We compared near-isogenic barley (Hordeum vulgare L.) germplasm varying in the allelic state of a major GPC quantitative trait locus on chromosome 6, delineated by molecular markers HVM74 and ABG458 and explaining approximately 46% of the variability in this trait. High GPC was consistently associated with earlier whole-plant senescence. SDS–PAGE and immunoblot analysis of flag leaf proteins indicated earlier leaf protein [including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)] degradation in high-GPC germplasm. This was accompanied by enhanced availability of ammonium and glutamine in developing kernels, suggesting increased phloem retranslocation of nitrogen. Based on previous microarray analysis, we performed a detailed expression study of six leaf genes, tentatively involved in plastidial proteolysis, vacuolar proteolysis, intermediary N metabolism and N transport. All of these were upregulated in high-GPC barley, mostly around 21 to 28 days past anthesis, prior to or around the time demonstrating maximal differences in leaf protein (including Rubisco) levels. Therefore, these genes represent potential targets to manipulate grain protein accumulation. It appears likely that their functional analysis will enhance our understanding of whole-plant N recycling. Additionally, earlier leaf (photosynthetic) protein degradation may lead to reduced N carbon assimilation in high-GPC germplasm, explaining past studies demonstrating a negative correlation between GPC and yield.
A mutation in GDP-mannose pyrophosphorylase causes conditional hypersensitivity to ammonium, resulting in Arabidopsis root growth inhibition, altered ammonium metabolism, and hormone homeostasis.
Barth, C., Gouzd, Z. A., Steele, H. P., & Imperio, R. M. (2010). Journal of Experimental Botany, 61(2), 379-394.
Ascorbic acid (AA) is an antioxidant fulfilling a multitude of cellular functions. Given its pivotal role in maintaining the rate of cell growth and division in the quiescent centre of the root, it was hypothesized that the AA-deficient Arabidopsis thaliana mutants vtc1-1, vtc2-1, vtc3-1, and vtc4-1 have altered root growth. To test this hypothesis, root development was studied in the wild type and vtc mutants grown on Murashige and Skoog medium. It was discovered, however, that only the vtc1-1 mutant has strongly retarded root growth, while the other vtc mutants exhibit a wild-type root phenotype. It is demonstrated that the short-root phenotype in vtc1-1 is independent of AA deficiency and oxidative stress. Instead, vtc1-1 is conditionally hypersensitive to ammonium (NH4+). To provide new insights into the mechanism of NH4+ sensitivity in vtc1-1, root development, NH4+ content, glutamine synthetase (GS) activity, glutamate dehydrogenase activity, and glutamine content were assessed in wild-type and vtc1-1 mutant plants grown in the presence and absence of high NH4+ and the GS inhibitor MSO. Since VTC1 encodes a GDP-mannose pyrophosphorylase, an enzyme generating GDP-mannose for AA biosynthesis and protein N-glycosylation, it was also tested whether protein N-glycosylation is affected in vtc1-1. Furthermore, since root development requires the action of a variety of hormones, it was investigated whether hormone homeostasis is linked to NH4+ sensitivity in vtc1-1. Our data suggest that NH4+ hypersensitivity in vtc1-1 is caused by disturbed N-glycosylation and that it is associated with auxin and ethylene homeostasis and/or nitric oxide signalling.
Reduction of acrylamide formation by vanadium salt in potato French fries and chips.
Kalita, D. & Jayanty, S. S. (2013). Food Chemistry, 138(1), 644-649.
The effects of vanadyl sulphate on the formation of acrylamide have been studied in fried potato products, such as French fries and chips. Acrylamide formation was inhibited by 30.3%, 53.3% and 89.3% when the sliced potato strips were soaked in 0.001, 0.01 and 0.1 M vanadyl sulphate (VOSO4) solutions, respectively, for 60 min before frying. Moreover, 57.7%, 71.4% and 92.5% inhibition of acrylamide formation was observed when chips were soaked in the respective vanadyl sulphate solution before frying. In a separate model reaction, a solution containing an equimolar concentration of L-asparagine and D-glucose showed a significant inhibition of acrylamide formation when heated at 150°C for 30 min in the presence of vanadyl sulphate (VOSO4). The results indicate that the binding of VO2+ to asparagine and the decrease in the pH of the potato samples resulted in a significant reduction of acrylamide formation in fried potato products.
Role of polyphenols in acrylamide formation in the fried products of potato tubers with colored flesh.
Kalita, D., Holm, D. G. & Jayanty, S. S. (2013). Food Research International, 54(1), 753-759.
The levels of asparagine, reducing sugars and total phenolics in some potato cultivars and advanced selections with distinctive flesh color (white, yellow, red and purple) and their potential in acrylamide formation in French fries and potato chips have been investigated in this study. The range of asparagine and reducing sugars were 1.8–9.0 and 1.35–11.7 mg/g respectively. There was no significant correlation of asparagine and reducing sugars with flesh color of the potato tubers. Tubers with red and purple flesh had higher levels of total phenolics than the white and yellow ones. The amount of acrylamide formed in French fries and chips were ranged from 128.1 to 1651.3 μg/kg and from 2104.3 to 2978.5 μg/kg respectively. The levels of asparagine and reducing sugars were positively correlated with acrylamide formation while total phenolics and chlorogenic acid correlated negatively.
cMyc increases cell number through uncoupling of cell division from cell size in CHO cells.
Kuystermans, D. & Al-Rubeai, M. (2009). BMC Biotechnology, 9(76).
Background: Over the past decades, the increase in maximal cell numbers for the production of mammalian derived biologics has been in a large part due to the development of optimal feeding strategies. Engineering of the cell line is one of probable approaches for increasing cell numbers in bioreactor. Results: We have demonstrated that the over-expression of the c-myc gene in immortalised CHO cells can increase proliferation rate and maximal cell density in batch culture compared to the control. The changes were attributed to a rapid transition into S-phase from a shortened duration of G1 phase and to the uncoupling of cell size from cell proliferation. To achieve the >70% increase in maximal cell density without additional supply of nutrients the cells underwent an overall reduction of 14% in size as well as a significant decrease in glucose and amino acid consumption rate. Consequently, the total biomass accumulation did not show a significant change from the control. The amount of hSEAP-hFc activity of the over expressing c-myc cell line was found to be within 0.7% of the control.Conclusion: It is shown that the manipulation of cell cycle kinetics and indirectly cell metabolism gives higher cell densities in CHO batch cultures. The unaltered apoptotic rate supported the proposition that the increase in cell number was a result of enhance cell cycle kinetics and cellular metabolism rather than increasing viability. Production of hSEAP-hFc from a constitutive c-myc over-expressing cell line did not increase with the increase in cell number.