Browsing by Subject "pH"

The literature review deals with water distribution in meat, the structure of the myofibrillar matrix, and the aspects related to the water-protein interaction. Special focus was given to the large water accessible area of myosin S1 units, surface hydrophobicity of proteins and factors affecting the hydrophobicity. Also the possible mechanisms of water-holding in meat were briefly introduced. The aim of the thesis was to study the effect of different ions and pH values on the surface hydrophobicity of the myosin S1 units, adding knowledge to the understanding of the interaction between myosin S1 units and water. Myosin S1 units were prepared from porcine longissimus dorsi muscle 48 h postmortem. Obtained myosin S1 units were subjected to 0.2 M, 0.4 M and 0.6 M ionic strength of NaCl and KCl and to pH 5.0, 5.5, 6.0, 6.5 and 7.0. The surface hydrophobicity of myosin S1 units was measured by fluorescent molecular probe (cis-Parinaric acid) method. The method of purifying myosin S1 units from porcine longissimus dorsi muscle 48 h postmortem was established under the conditions of our laboratory. Surface hydrophobicity was found to increase with increasing ionic strength of both KCl and NaCl. Concerning the different ions studied, only at 0.6 M, significantly higher surface hydrophobicity of myosin S1 units was measured in KCl compared to NaCl. This phenomenon is in accordance with chaotropic effect of K+ and Cl- and kosmotropic effect of Na+. Regarding the effect of pH, within KCl samples, more hydrophobicity myosin S1 unit was detected towards to the more acidic direction pH values than pH 6.0. For NaCl samples, at pH 5.5 and 6.0, surface hydrophobicity was significantly higher than at pH 5.0, 6.5 and 7.0. Differences may have been induced by the changes in the net charges of protein, and further in protein conformation. Considering the property of the protein surface, more hydrophobic protein results in less water-protein interaction. However, to look at the whole scenario of the interaction between myosin S1 units and water, changes of net charges of myosin S1 units and water structure at vicinity of them should be further studied.

Poultry meat has become popular in human diet and to secure the growing demand of poultry meat, breeders have developed broilers with fast growth and high breast muscle yield. Because of this genetic selection modern broilers are suffering from various quality defects in their breast muscles, one of which is called WB myopathy. The aim of the thesis was to study whether exercise, WB status or age have effects on ultimate pH and glycolytic potential (sum of total glucose and lactic acid content, given as lactate) in M. pectoralis major of modern broilers chickens. A total of 154 post-rigor breast muscle samples of male broilers of hybrid Ross 308 were used in this study. Broilers were divided randomly into three groups (A-C). Group A birds were not subjected to any exercise during the experiment. Group B birds lived 25 days exactly like group A but after that the drinking water dispensers was elevated to a higher level. Group C birds had their drinking water dispensers elevated to a 5 cm higher level after three days, and it was risen stepwise to 25 cm during the study. Broilers were slaughtered randomly from different groups at 20, 30 or 41 days old. Group B results were disregarded due to technical problems. Initial and ultimate pH, total glucose, free and in glycogen, and lactic acid contents for glycolytic potential, were determined from the breast muscle samples. The results showed that there were no differences between groups A and C (p > 0.05). There were differences between normal and WB cases in ultimate pH (pHu; p = 0.000), total glucose content (p = 0.000), lactate content (p = 0.007) and glycolytic potential (p = 0.000), but the pH values 5 minutes after death showed no significance (pH5; p = 0.190). There were differences in pHu, total glucose and glycolytic potential (p = 0.000), and lactate (p = 0.007), between ages 20, 30 and 41 days old birds. As the severity of WB increased in the breast muscle, the pHu increased and total glucose, lactate content and glycolytic potential decreased. The correlations showed significant relationships between WB score and all the above variables (p < 0.000). The results of the current study show that exercise does not have an effect on the levels of carbohydrates in M. pectoralis major of modern broiler chickens, but WB status and increasing slaughter age result a decrease in glycolytic potential and increase in ultimate pH.

Loppijärvi on Kanta-Hämeessä sijaitseva matala humusjärvi, jonka rehevöityminen on edennyt poikkeuksellisen nopeasti viimeisen kymmenen vuoden aikana. Useista hoito- ja kunnostustoimista huolimatta järven rehevöityminen on jatkunut voimakkaana ja tilannetta pidetään huolestuttavana. Järven veden laadussa tapahtuneista muutoksista vesikasvillisuudesta ja kalastosta on saatavilla paljon tutkittua tietoa. Sen sijaan järven pohjasedimentistä tiedetään hyvin vähän. Tämän pro gradu -tutkielman tavoitteena oli kartoittaa järven pohjasedimentin tilaa, luoda yleiskuva järven rehevöitymiseen vaikuttavista fysikaalis-kemiallisista ominaisuuksista sekä arvioida sedimentin kuormituspotentiaaliin vaikuttavien ilmiöiden merkitystä. Tutkimus koostui kahdesta osasta. Ensimmäisessä tutkittiin järven pohjasedimentin ominaisuuksia järven eri osista otettujen sedimenttinäytteiden ja niistä määritettyjen raudan, alumiinin, kalsiumin ja fosforin kokonaispitoisuuksien avulla. Toinen osa koostui muhituskokeesta, jossa tarkasteltiin sedimentin happitilan ja järvikunnostuksessa yleisesti käytetyn alumiinikloridin vaikutuksia sedimentin sisältämän fosforin pidättymiseen ja jakautumiseen sekä arvioitiin sen soveltumista järvikunnostukseen laboratoriomittakaavassa. Sedimenttitutkimuksen perusteella Loppijärven nykyinen rehevöitymiskehitys johtuu sisäisestä kuormituksesta, eikä järveen kohdistu kuormitusta pistemäisistä lähteitä. Loppijärven sedimentin Fe:P-suhde vaihteli välillä 15–30. Sedimentin fosforipitoisuus oli noin 2,1 g P kg-1 koko sedimenttiprofiilin syvyydellä ja Fe:P-suhteen vaihtelu johtui pääasiassa sedimentin rautapitoisuudesta. Tulosten perusteella sedimentin fosforinpidätyskyky ei vastannut Fe:Psuhdetta, mikä viittaa muiden tekijöiden vaikuttavan raudan kykyyn pidättää fosforia. Muhituskokeen perusteella alumiinikloridikäsittely ei soveltunut sitomaan fosforia alumiinin aiheuttaman happamoitumisen takia. Alumiinikloridikäsittelyn vaikutus fosforin käyttäytymiseen vaihteli näytteiden hapetustilasta riippuen. Tulosten perusteella rauta sääteli fosforin vapautumista sedimentistä ja paras tulos kunnostustavoitteiden kannalta saatiin hapellisissa olosuhteissa ilman alumiinikloridikäsittelyä. Sedimenttitutkimuksen perusteella kemikaalikäsittelyt voivat auttaa kunnostustavoitteiden saavuttamisessa, mutta rehevöitymisen pysäyttäminen vaatii toimenpiteitä, jotka vaikuttavat sedimentissä vallitseviin olosuhteisiin tai sisäistä kuormitusta sääteleviin prosesseihin.

The current trend in the food and forest industries is to utilize sustainable and renewable products. One such product is galactoglucomannans (GGM), water-soluble hemicelluloses covering 25–35 % of the dry wood mass. GGM can be extracted from spruce sawdust or branches using a safe and environmentally friendly pressurized hot water extraction (PHWE) method. Deacetylation of GGM happening during extraction and concentration by membrane filtration at alkali conditions possibly enables gel formation. This thesis aims to observe if low acetyl GGM has the ability to form a gel and which factors have an impact on its gelation and gel properties. Low acetyl PHWE GGM powders were provided by the Natural Resources Institute of Finland (Luke). The GGM solutions at different pH values (4, 7, and 10) and solid concentration levels (5, 10, and 15 %) were prepared using a magnetic stirring rod and then ultrasonicated (50% amplitudes for 5 min). Viscosity, rheological properties, water holding capacity (WHC), hardness, and adhesiveness were measured on days 1, 2, 3, and 5 during storage at room temperature (22 °C). The results showed that GGM was able to form a gel at all investigated conditions, except for the samples at pH 4 and a solid concentration of 5 %. GGM solutions at high pH (7–10) and solid concentrations (10–15%) formed gels without ultrasonication. All GGM gels had high WHC (≥ 90 %). Gel viscosity increased with prolonging of storage time and increased solid concentration. The frequency sweep analyses showed that all investigated samples had a gel-like behavior. Gel hardness and adhesiveness increased in all the samples during storage and increased solid concentration. The thesis demonstrated that low acetyl GGM could form a gel, which could be used as a gelling agent, where solid concentration and pH impacted to gel structure. Thus, the study could widen industrial applications of GGM or at least engage interest.

Tiivistelmä - Referat – Abstract Acid sulfate soils are formed from sediment deposits containing sulfides, in which sulfur is present in the form of iron sulfides. In contact with air, the sulfur layer initiates a long-chain of biochemical and chemical reactions that increase the acidity of the soil and the amount of sulfate. Excessive acidity restricts plant development and growth. In acid soil, the aluminum solubility reaches a high level of toxicity for roots and slows down the microbiological degradation of organic matters, resulting in a reduction of nitrogen mineralization. Previous research results have shown that important liming has the potential to raise the pH of sulphate soils, and thereby reduce its acidity. With a high pH, the concentrations of ammonium and nitrate in the soil increase, facilitating nitrogen uptake and thereby also improving the efficiency of nitrogen uptake by plants. It has been speculated that, by increasing the nitrogen uptake efficiency and nitrogen utilization in plants, it will improve nitrogen use efficiency and so will reduce denitrification in sulphate soils and the resulting N2O emissions. However, to date, the studies on the effect of liming on plant nitrogen uptake (UPE) and utilization efficiency (UTE) and, consequently, on plant nitrogen utilization efficiency (NUE) have been minimal. The purpose of this study is to investigate how liming affects the yield formation and nitrogen uptake efficiency for barley (Hordeum vulgare L.) in unfertilized and fertilized acid sulfate soils. The field trial was established in Viikki, Helsinki, in the spring 2018. It followed split-plot design, in which the main plots were combinations of plant and nitrogen fertilization treatments (0 or 100 kg of nitrogen per hectare of fertilized barley (Kaarle) or unfertilized fallow) and lime treatments (0; 7,7; 15,3 t/ha) in four replicates. Liming raised the soil pH as expected and also increased nitrogen mineralization during the growing season, which is reflected in the nitrogen uptake. The effect of liming and fertilization on crop formation was small for barley biomass, yield component and grain yield. On the other hand, the liming effect reduced the nitrogen absorption efficiency and the nitrogen utilization efficiency and thereby the efficiency of nitrogen use. Fertilization also increased nitrogen uptake, but also decreased nitrogen utilization efficiency and nitrogen harvest index. The combined effect of liming and fertilization increased nitrogen mineralization. Liming treatment clearly increased nitrogen mineralization more in unfertilized soils than fertilized (there was no difference between liming levels). The drought in June and the low moisture limited the mobilization of nitrogen released from fertilizer in the soil, which would explain the effect of the nitrogen fertilizer treatment remaining relatively small. The drought also limited the development of the roots and thus the uptake of nitrogen and other nutrients. Lime treatment did not change NUE, UPE and UTE, but increased nitrogen mineralization and nitrogen uptake during the growing season, suggesting that under more favorable conditions the liming treatment could improve the efficiency and therefore improve the profitability and ecology of the barley crop. Further studies are needed as the results of studies performed elsewhere may not be valid under boreal conditions.

Tämä syventävien opintojen tutkielma sisältää kirjallisuuskatsauksen ja tutkimusosan. Kirjallisuskatsauksessa käsitellään kalkkunan kehitystä massiiviseksi lihantuotantoeläimeksi, kalkkunan sairauksia sekä perehdytään lihaksen rakenteeseen, toimintaan ja biokemiallisiin muutoksiin teurastuksen jälkeen. Lisäksi on käsitelty siipikarjanlihan laatuun ja pH-arvon muutoksiin vaikuttavia tekijöitä. Tutkimusosassa käsitellään kalkkunoista teurastuksen jälkeen mitattuja pH-arvoja. Tarkoituksena oli määrittää kalkkunan ruhon pH-arvo teurastuksen jälkeen sekä tutkia taustamuuttujien vaikutusta ph-muutoksiin. Rinta- ja jalkalihaksesta mitattiin pH-arvo heti teurastuksen jälkeen ja vuorokauden kuluttua. Taustamuuttujina olivat-kalkkunan ikä, laatuluokka, kasvattaja, kuljetusaika, makroskooppiset muutokset sekä vuodenaika. Rintalihaksen pH-arvoksi saatiin 6.7+-0.3, 15-20minuuttia teurastuksesta. Jalkalihaksen pH-arvo oli 6.7+-0.2. Vuorokauden kuluttua teurastuksesta rintalihaksen pH-arvo oli 5.8+-0.1 ja jalkalihaksen 6.0+-0.1. Taustamuuttuja ryhmissä oli vain vähäisiä eroja pH-arvojen välillä. Kalkkunan iällä ja kuljetusajalla havaittiin suurin vaikutus teurastuksen jälkeiseen pH-arvoon. Tutkimuksen mukaan pH-arvoa ei voi käyttää jaotteluperusteena luokiteltaessa kalkkunoita makroskooppisten muutosten mukaisiin laatuluokkiin.

Eight active farms participated in the OSMO-project between years 2015 and 2018. Each farm had unique soil health related challenges. The aim of this work was to identify factors related to soil manganese concentration and mobility and develop tools and materials to help farmers better to understand manganese related soil health issues. Manganese cycling and mobility in soils was analysed through soil structure, electric conductivity (EC), SOM, pH and soil iron concentration. Soil manganese concentration was evaluated with three indicators: pH-corrected acid ammonium acetate + EDTA extractable manganese, acid ammonium acetate + EDTA extractable manganese and the amount of manganese available to plants based on the volume of soil available for root growth. Foliar fluorescence measurement to evaluate manganese deficiency in plant tissues is shortly discussed. Soil manganese concentrations and mobility in soil profiles varied because of soil chemical and biological properties but also because of farming practices and changes in physical soil properties. To improve manganese availability in arable farming, soil health analysis through multiple indicators together with consistent soil health improvement and crop rotation is recommended for all active farms. When using fluorescence measurements to evaluate the need for foliar manganese fertilisation, the use of control solution is necessary for reliable results. More research is needed on manganese efficient crops and crop rotation and its effects on manganese cycle and availability in soils. To improve scientific understanding on soil processes, more research is needed about soil redox-reactions, electric conductivity, pH and how the dynamic change in soil Eh-pH environment relates to soil health.

Tiivistelmä gradun pdf-tiedostossa.

Lepidurus arcticus (Pallas, 1793) is a keystone species in High Arctic ponds, which are exposed to a wide range of environmental stressors. This thesis provides information on the ecology of this little studied species by paying particular focus on the sensitivity of L. arcticus to acidification and climate change. Respiration, reproduction, olfaction, morphology, salinity and pH tolerance of the species were studied in the laboratory and several environmental parameters were measured in its natural habitats in Arctic ponds. Current global circulation models predict 2–2.4 °C increase in summer temperatures on Spitsbergen, Svalbard, Norway. The L. arcticus respiration activity was tested at different temperatures (3.5, 10, 16.5, 20, 25 and 30 °C). The results show that L. arcticus is clearly adapted to live in cold water and have a temperature optimum at +10 °C. This species should be considered as stenothermal, because it seems to be able to live only within a narrow temperature range. L. arcticus populations seem to have the capacity to respond to the ongoing climate change on Spitsbergen. Changes can be seen in the species' reproductive capacity and in the individuals' body size when comparing results with previous studies on Spitsbergen and in other Arctic areas. Effective reproduction capacity was a unique feature of the L. arcticus populations on Spitsbergen. L. arcticus females reached sexual maturity at a smaller body size and sexual dimorphism appeared in smaller animals on Spitsbergen than anywhere else in the subarctic or Arctic regions. L. arcticus females were able to carry more eggs (up to 12 eggs per female) than has been observed in previous studies. Another interesting feature of L. arcticus on Spitsbergen was their potential to grow large, up to 39.4 mm in total length. Also cannibalistic behaviour seemed to be common on Spitsbergen L. arcticus populations. The existence of different colour morphs and the population-level differences in morphology of L. arcticus were unknown, but fascinating characteristic of this species. Spitsbergen populations consisted of two major (i.e. monochrome and marbled) and several combined colour morphs. Third interesting finding was a new disease for science which activated when the water temperature rose. I named this disease to Red Carapace Disease (RCD). This High Arctic crustacean lives in ponds between the Arctic Ocean and glaciers, where the marine environment has a strong impact on the terrestrial and freshwater ecosystems. The tolerance of L. arcticius to increased water salinity was determined by a LC50 -test. No mortality occurred during the 23 day exposure at low 1–2 ‰ water salinity. A slight increase in water salinity (to 1 ‰) speeded up the L. arcticus shell replacement. The observations from natural populations supported the hypothesis that the size of the animals increases considerably in low 1.5 ‰ salt concentrations. Thus, a small increase in water salinity seems to have a positive impact on the growth of this short-lived species. Acidification has been a big problem for many crustaceans, invertebrates and fishes for several decades. L. arcricus does not make an exception. Strong acid stress in pH 4 caused a high mortality of mature L. arcticus females. The critical lower limit of pH was 6.1 for the survival of this acid sensitive species. Thus, L. arcticus populations are probably in danger of extinction due to acidification of three ponds on Spitsbergen. A slight drop (0.1–1.0) in pH values can wipe out these L. arcticus populations. The survival of L. arcticus was strongly related to: (1) the water pH, (2) total organic carbon (TOC) and pH interaction, (3) the water temperature and (4) the water salinity. Water pH and TOC values should be monitored in these ponds and the input of acidifying substances in ponds should be prevented.