Protein cross-linking with oxidative enzymes and transglutaminase : Effects in meat protein systems

The effects of tyrosinase, laccase and transglutaminase (TG) were studied in different meat protein systems. The study was focused on the effects of the enzymes on the gel formation properties of myofibrils, and on the textural and water-holding properties of the heated meat systems. The cross-linking efficiency of a novel Trichoderma reesei tyrosinase was compared to that of the commercial Agaricus bisporus tyrosinase. Trichoderma tyrosinase was found to be superior compared to the Agaricus enzyme in its protein cross-linking efficiency and in the incorporation of a small molecule into a complex proteinaceous substrate. Tyrosinase, laccase and TG all polymerised myofibrillar proteins, but laccase was also found to cause protein fragmentation. A positive connection between covalent cross-link and gel formation was observed with tyrosinase and TG. Laccase was able to increase the gel formation only slightly. With an excessive laccase dosage the gel formation declined due to protein fragmentation. Tyrosinase, laccase and TG had different effects on the texture and water-holding of the heated chicken breast meat homogenates. Tyrosinase improved the firmness of the homogenate gels free of phosphate and with a low amount of meat. TG improved the firmness of all studied homogenates. Laccase weakened the gel firmness of the low-meat, low-salt and low-salt/phosphate homogenates and maintained the firmness on the control level in the homogenate free of phosphate. Tyrosinase was the only enzyme capable of reducing the weight loss in the homogenates containing a low amount of meat and a low amount of NaCl. TG was the only enzyme that could positively affect the firmness of the homogenate gel containing both low NaCl and phosphate amounts. In pilot scale the test products were made of coarsely ground chicken breast fillet with a moderate amount of salt. Increasining the amount of meat, salt and TG contents favoured the development of firmness of the test products. The evaporation loss decreased slightly along with increasing TG and NaCl amounts in the experimental conditions used, indicating a positive interaction between these two factors. In this work it was shown that tyrosinase, laccase and TG affected the same myofibrillar proteins, i.e. myosin and troponin T. However, these enzymes had distinguishable effects on the gel formation of a myofibril system as well as on the textural and water-holding properties of the finely ground meat homogenates, reflecting distinctions at least in the reaction mechanisms and target amino acid availability in the protein substrates for these enzymes.

Glycogen debranching enzyme activity in the muscles of meat producing animals

Muscle glycogen exists in two forms: low molecular weight pro-glycogen and high molecular weight macro-glycogen. The degradation of glycogen to glucose 1 phosphate and free glucose is catalysed by glycogen phosphorylase together with glycogen debranching enzyme (GDE). The process in which glycogen is broken down via anaerobic pathways to lactate, results in the acidification of the muscles and has a great influence on meat quality. Thus, the overall aim of this thesis was to characterise the post mortem action of GDE in muscles of meat production animals (pigs, cattle and chickens). Interest was focused on the differences in GDE activity between fast twitch glycolytic muscles and slow twitch oxidative muscles. The effects of pH, temperature, RN genotype (PRKAG3 gene), and of time post mortem on GDE activity were also investigated. This thesis showed that there are differences in GDE activity between animal species and between different muscles of an animal. It was shown that in pigs and cattle, higher GDE activity and phosphorylase activity exists in the fast twitch glycolytic muscles than in slow twitch oxidative muscles of the same animal. Thus, the high activity of these enzymes enables a faster rate of glycogenolysis in glycolytic M. longissimus dorsi compared to oxidative M. masseter. In chicken muscles, the GDE activity was low compared to pig or cattle muscles. Furthermore, the GDE activity in the glycolytic M. pectoralis superficialis was lower than in more oxidative M. quadriceps femoris despite the high phosphorylase activity in the former. The relative ratios between phosphorylase and GDE activity were higher in fast twitch glycolytic muscles than in slow twitch oxidative muscles of all studied animals. This suggests that the relatively low GDE activity compared to the phosphorylase activity in fast twitch glycolytic muscles may be a protection mechanism in living muscle against a very fast pH decrease. Chilling significantly decreased GDE activity and below 15 C porcine GDE was almost inactive. The effect of pH on GDE activity was only minor at the range normally found in post mortem muscles (pH 7.4 to 5.0). The GDE activity remained level for several hours after slaughter. During the first hours post mortem, GDE activity was similar in RN- carrier pigs and in wild type pigs. However, the GDE activity declined faster in M. longissimus dorsi from wild type pigs than in the RN carrier pigs, the difference between genotypes was significant after 24 h post mortem. Pro-glycogen and macro-glycogen contents were higher, pH decrease was faster and ultimate pH was lower in RN- carrier pigs than in wild type pigs. In the RN- carriers, the prolonged high GDE activity level may enable an extended pH decrease and lower ultimate pH in their muscles. In conclusion, GDE is not the main factor determining the rate or the extent of post mortem glycogenolysis, but under certain conditions, such as in very fast chilling, the inhibition of GDE activity in meat may reduce the rate of pH decrease and result in higher ultimate pH. The rate and extent of pH decrease affects several meat quality traits.

Inhibitory effects of wood extracts on the spoilage flora of marinated poultry meat

Polyphenolic compounds occurring naturally in knotwood of plants are known to have antimicrobial effects. The knots (i.e. the branch bases inside tree stems) and outer branches in pine trees contain a remarkably high concentration of phenolic stilbenes, while lignans are the major phenolic constituents of spruce knots. Large amount of these phenolic compounds can be extracted from wood knots at pulp and paper mills where their presence is undesirable. In Finland, marinating of broiler meat is done not only to increase or add value to the meat, but also to enhance the safety and shelf-life. These products are usually packed under a modified atmosphere for further protection against spoilage microorganisms. However, studies have revealed that addition of marinades to poultry products do not have an inhibitory effect on either some psychrotrophic anaerobic bacteria, such as Brochothrix thermosphacta or lactic acid bacteria associated with spoilage. Also, the activity of pathogenic Campylobacter jejuni is not affected by marinating. The objective of this study was to investigate the inhibitory and lethal activities of extracts from spruce (Picea spp.) and pine (Pinus spp.) knotwood and outer branches that are dissolved in ethanol against the spoilage microorganisms in modified atmosphere packaged marinated broiler products. Modified atmosphere packaged broiler products were separately inoculated with ‘normal’ marinades, marinades with 70% ethanol, marinades with a mixture of spruce and pine extracts dissolved in 70% ethanol or mixture of spruce and pine extracts in powder form. The bacterial colony forming units per gram obtained from each of the samples were analysed on de Man Rogosa and Sharpe agar at days 1, 6, 12 and 15. The results showed that there were significant differences in bacterial colony forming units per gram (P <0.05) between packages with ‘normal’ marinades and packages with extracts added to their marinades on the 12th and 15th day. It can be concluded that the addition of extracts from spruce and pine knotwood to marinades significantly retarded growth of spoilage microorganisms during the 15 day test period. However further research is warranted to characterise and establish the safety and suitability of the compound(s) in spruce and pine knotwood extracts that are responsible for inhibitory or lethal activity against the microbes that may be present in marinated poultry meat.

Nuori konservatiivi : Tuure Junnila ja hänen poliittinen toimintansa vuoteen 1956

Tuure Junnila, PhD (1910-1999) was one of Finland's most renowned conservative politicians of the post-war period. Junnila is remembered primarily as a persistent opponent of Urho Kekkonen, a long-term Member of Parliament, a conspicuous opposition member and a prolific political writer. Junnila's ideologies and political views were conservative, and he is one of the most outstanding figures in the history of the National Coalition Party. Junnila also made an extensive career outside of politics, first as an economist and then as an executive of Finland's leading commercial bank Kansallis-Osake-Pankki. The Young Conservative is a partial biography written using traditional historical research methods, which examines Junnila's personal history and his activity in public life up to 1956. The study begins by investigating Junnila's background through his childhood, school years, university studies and early professional career. It also looks at Junnila's work as an economist and practical banker. Particular attention is paid to Junnila's political work, constantly focusing on the following five often overlapping areas: (1) economic policy, (2) domestic policy, (3) foreign and security policy, (4) Junnila and Urho Kekkonen, (5) Junnila, the Coalition Party and Finnish conservatism. In his economic policy, Junnila emphasised the importance of economic stability, opposed socialisation and the growth of public expenditure, defended the free market system and private entrepreneurship, and demanded tax cuts. This policy was very popular within the Coalition Party during the early 1950s, making Junnila the leading conservative economic politician of the time. In terms of domestic policy, Junnila demanded as early as the 1940s that a "third force" should be established in Finland to counterbalance the agrarian and labour parties by uniting conservative and liberal ideologies under the same roof. Foreign and security policy is the area of Junnila's political activity which is most clearly situated after the mid-1950s. However, Junnila's early speeches and writings already show a striving towards the unconditional neutrality modelled by Switzerland and Sweden and a strong emphasis on Finland's right to internal self-determination. Junnila, as did the Coalition Party as a whole, adopted a consistently critical approach towards Urho Kekkonen between 1951 and 1956, but this attitude was not as bluntly negative and all-round antagonistic as many previous studies have implied. Junnila was one of the leading Finnish conservatives of the early 1950s and in all essence his views were analogous to the general alignment of the Coalition Party at the time: conservative in ideology and general policy, and liberal in economic policy.

Järjestö jäänmurtajana : Suomen merimiesunioni työmarkkinaosapuolena ja suomalaisten laivatyöntekijöiden turvallisuuden vankentajana 1944-1980

Like an Icebreaker: The Finnish Seamen s Union as collective bargaining maverick and champion of sailors social safety 1944-1980. The Finnish Seamen's Union (FSU), which was established on a national basis in 1920, was one of the first Finnish trade unions to succeed in collective bargaining. In the early 1930s, the gains made in the late 1920s were lost, due to politically based internal rivalries, the Great Depression, and a disastrous strike. Unexpectedly the FSU survived and went on promoting the well-being of its members even during World War II. After the war the FSU was in an exceptionally favorable position to exploit the introduction of coordinated capitalism, which was based on social partnership between unions, employers and government. Torpedoes, mines and confiscations had caused severe losses to the Finnish merchant marine. Both ship-owners and government alike understood the crucial importance of using the remaining national shipping capacity effectively. The FSU could no longer be crushed, and so, in 1945, the union was allowed to turn all ocean-going Finnish ships into closed shops. The FSU also had another source of power. After the sailors of the Finnish icebreaker fleet also joined its ranks, the FSU could, in effect, block Finnish foreign trade in wintertime. From the late 1940s to the 1960s the union started and won numerous icebreaker strikes. Finnish seamen were thus granted special pension rights, reductions on income taxes and import duties, and other social privileges. The FSU could neither be controlled by union federations nor intimidated by employers or governments. The successful union and its tactically clever chairperson, Niilo Välläri, were continuously but erroneously accused of syndicalism. Välläri did not aim for socialism but wanted the Finnish seamen to get all the social benefits that capitalism could possibly offer. Välläri s policy was successfully followed by the FSU until the late 1980s when Finnish ship-owners were allowed to flag their vessels outside the national registry. Since then the FSU has been on the defensive and has yielded to pay cuts. The FSU members have not lost their social benefits, but they are under constant fear of losing their jobs to cheap foreign labor.

"Secoituxesta järjettömäin luondocappalden canssa" : Perversiot, oikeuselämä ja kansankulttuuri 1700-luvun Suomessa

Bestiality was in the 18th century a more difficult problem in terms of criminal policy in Sweden and Finland than in any other Christian country in any other period. In the legal history of deviant sexuality, the phenomenon was uniquely widespread by international comparison. The number of court cases per capita in Finland was even higher than in Sweden. The authorities classified bestiality among the most serious crimes and a deadly sin. The Court of Appeal in Turku opted for an independent line and was clearly more lenient than Swedish courts of justice. Death sentences on grounds of bestiality ended in the 1730s, decades earlier than in Sweden. The sources for the present dissertation include judgment books and Court of Appeal decisions in 253 cases, which show that the persecution of those engaging in bestial acts in 18th century Finland was not organised by the centralised power of Stockholm. There is little evidence of local campaigns that would have been led by authorities. The church in its orthodoxy was losing ground and the clergy governed their parishes with more pragmatism than the Old Testament sanctioned. When exposing bestiality, the legal system was compelled to rely on the initiative of the public. In cases of illicit intercourse or adultery the authorities were even more dependent on the activeness of the local community. Bestiality left no tangible evidence, illegitimate children, to betray the crime to the clergy or secular authorities. The moral views of the church and the local community were not on a collision course. It was a common view that bestiality was a heinous act. Yet nowhere near all crimes came to the authorities' knowledge. Because of the heavy burden of proof, the legal position of the informer was difficult. Passiveness in reporting the crime was partly because most Finns felt it was not their place to intervene in their neighbours' private lives, as long as that privacy posed no serious threat to the neighbourhood. Hidden crime was at least as common as crime more easily exposed and proven. A typical Finnish perpetrator of bestiality was a young unmarried man with no criminal background or mental illness. The suspects were not members of ethnic minorities or marginal social groups. In trials, farmhands were more likely to be sentenced than their masters, but a more salient common denominator than social and economical status was the suspects' young age. For most of the defendants bestiality was a deep-rooted habit, which had been adopted in early youth. This form of subculture spread among the youth, and the most susceptible to experiment with the act were shepherds. The difference between man and animal was not clear-cut or self-evident. The difficulty in drawing the line is evident both in legal sources and Finnish folklore. The law that required that the animal partners be slaughtered led to the killing of thousands of cows and mares, and thereby to substantial material losses to their owners. Regarding bestiality as a crime against property motivated people to report it. The belief that the act would produce human-animal mongrels or that it would poison the milk and the meat horrified the public more than the teachings of the church ever could. Among the most significant aspects in the problems regarding the animals is how profoundly different the worldview of 18th century people was from that of today.

Teollisuuden ja yhteiskunnan palveluksessa : Arkkitehti Bertel Liljequist (1885 - 1954) tuotantolaitosten suunnittelijana maailmansotien välisenä aikana

My thesis concerns the plans drawn up by architect Bertel Liljequist (1885 1954) for an industrial corporation and a city in Finland during the interwar years. These were two quite different clients: the Kymi Company operating in Kuusankoski and the City of Helsinki. My study includes the micro-examination of the wider social issues involved. That the industrial community and factories in Kuusankoski be constructed correctly in a way supporting corporate strategy was of primary importance for the company s operations. Through the planning process for Helsinki s abattoirs, I show how a city dealt with the twin problems of hygiene and increasing demand for food resulting from a growth in population. I clarify how society and its economic, political and class structures affected the practice of architecture and its expression in the built environment. I analyse how the different backgrounds and starting points of the clients affected the construction projects under study and architect Bertel Liljequist s work. In studying Liljequist as an industrial designer, I have considered it vital to ascertain the client s intentions and objectives within the framework of the prevailing social situation. I examine the meanings the client wished the architecture to express and also to communicate to those working in the factory and the area as well as to the workers living on company land. The social outlook of the owners and management of Kymi Company implicitly affected the appearance of the factory. A brick fairface for the factories was a safe and natural material at the beginning of the 1920s when taking into consideration the events of the 1918 Civil War. To have built a White factory in the style of a defence building would have been provocative. Outside the factory gates, however, the company supported White architecture. The company used the factory buildings to manifest its power and the dwellings to bind the workers and make them loyal to the company. Architecture was thus one way in which the company manifested its position as the higher and undisputed authority. The role of the City of Helsinki within the planning process was for its officials to provide expert opinions but also to arrange study trips for the architect and the abattoir s general manager. The city also decided on the standard of the design. The city s responsibility for the health of its inhabitants and the requirements of modern meat production can be seen in the minimal architecture and clear functionality of the plant. The architecture left no doubt about the trustworthiness of the modern city. Translation: Michael Wynne-Ellis

Campylobacter Infections of Domestic Origin in Finland

Campylobacter jejuni and C. coli are the leading causes of human bacterial gastroenteritis in developed countries. Most human Campylobacter infections are sporadic and a seasonal peak in the distribution of infections can be seen in the summer months in several countries, including Finland. A variety of risk factors for Campylobacter infections have been identified; handling and eating poultry, drinking unpasteurized milk, contact with domestic animals, and travelling abroad. However, the relative importance of the different risk factors in sporadic cases of Campylobacter infection remains unknown. In most cases, the infection is self-limiting and no specific treatment is required. Campylobacter enteritis can cause a wide range of complications, including reactive arthritis (ReA) that is reported in 1-5% of the cases. Seven clinical microbiology laboratories serving different geographical areas of Finland, participated in this multi-centre study, conducted during a seasonal peak in 2002. In a matched case-control study, domestically-acquired sporadic Campylobacter infections from three geographical areas were collected. The final study comprised 100 cases and 137 controls. Risk factors for sporadic domestically-acquired Campylobacter infections were identified on the basis of a questionnaire; swimming in natural waters was found to be a novel risk factor for Campylobacter infection. Other independent risk factors were tasting or eating raw or undercooked meat and drinking untreated water from a dug well. The role of bacterial strain and host characteristics are not fully understood in Campylobacter infections. Exposure factors, demographical characteristics, and the serotype of the Campylobacter isolate may affect the severity of the enteritis. This cross-sectional study comprised 114 patients with C. jejuni enteritis, diagnosed in three clinical microbiology laboratories; most of the patients had participated in the previous case-control study. Swimming was associated with age ≤ 5 years and serotype Pen 6,7 was found significantly more often among patients reporting swimming. The geographical distribution among serotypes varied; serotype Pen 4-complex appeared more often in patients from urban areas and serotype Pen 21 among patients from more rural areas. Thus, risk factors and sources of infection for C. jejuni infection may vary among individuals depending on age and geographical location. The in vitro susceptibilities of C. jejuni and C. coli strains isolated from patients infected abroad (85 strains) or domestically (393 strains) revealed that susceptibility to erythromycin is still high, even among isolates of foreign origin. However, the novel antimicrobial agent telithromycin did not offer any advantage over erythromycin; isolates with high minimal inhibitory concentrations (MICs) for erythromycin also showed reduced susceptibility to telithromycin. Reduced susceptibility to fluoroquinolones was detected almost exclusively among isolates of foreign origin and half of these isolates with high MICs for fluoroquinolones also showed elevated MICs for doxycycline. Questionnaires concerning complications associated with C. jejuni enteritis were sent to patients two months after becoming ill; 201 patients from seven different geographical areas were included in the study. Musculoskeletal complications after C. jejuni infection were commonly reported by patients (39%). The incidence of classical ReA was 4% and that of Achilles enthesopathy and/or heel pain 9%. Other C. jejuni-associated reactive joint symptoms were commonly reported, however, due to their milder nature seldom seen and diagnosed by a physician. The severity of the enteritis may predict further complications; stomach ache during enteritis was connected to the development of later joint pain. Early antimicrobial treatment, within two days from the start of symptoms, shortened the duration of diarrhoea by two days but did not prevent later musculoskeletal complications. Campylobacter is an important human enteropathogen and causes a significant burden of illness. As the incidence of Campylobacter infections is high, the importance of the infection and the occurrence of complications will increase. This stresses the importance of understanding the risk factors for acquiring Campylobacter infection and how bacterial strain and host characteristics may affect the risk for infection. The role of antimicrobial treatment for acute Campylobacter enteritis seems to be marginal and should be used restrictively.

Fuel conditions and fire behavior characteristics of managed Picea abies and Pinus sylvestris forests in Finland

The objectives of this study were to analyze the impact of structural stand characteristics on ignition potential, surface fuel moisture, and fire behavior in Pinus sylvestris L. and Picea abies (L.) Karst stands in Finland and to explain stand-specific fire danger using the Canadian Fire Weather Index System and the Finnish Fire Risk Index. Additionally, the study analyzes the relationship between observed fire activity and fire weather indices at different stages of growing season. Field experiments were carried out in Pinus sylvestris or Picea abies dominated stands during fire seasons 2001 and 2002. Observations on ignition potential, fuel moisture, and fire behavior were analyzed in relation to stand structure and the outputs of the Finnish and Canadian fire weather indices. Seasonal patterns of fire activity were examined based on national fire statistics 1996 2003, effective temperature sum, and the fire weather indices. Point fire ignition potential was highest in Pinus clear-cuts and lowest in closed Picea stands. Moss-dominated surface fuels were driest in clear-cut and sapling stage stands and presented the highest moisture content under closed Picea canopy. Pinus sylvestris stands carried fire under a wide range of fire weather conditions under which Picea abies stands failed to sustain fire. In the national fire records, the daily number of reported ignitions presented its highest value during late fire season whereas the daily area burned peaked most substantially during early season. The fire weather indices correlated significantly with ignition potential and fuel moisture but were unable to explain fire behavior in the experimental fires. During the initial and final stages of the growing season, fire activity was disconnected from weather-based fire danger ratings. Information on stand structure and season stage would benefit the assessment of fire danger in Finnish forest landscape for fire suppression and controlled burning purposes.

Effect of phenolic-rich plant materials on protein and lipid oxidation reactions

The antioxidant activity of natural plant materials rich in phenolic compounds is being widely investigated for protection of food products sensitive to oxidative reactions. In this thesis plant materials rich in phenolic compounds were studied as possible antioxidants to prevent protein and lipid oxidation reactions in different food matrixes such as pork meat patties and corn oil-in water emulsions. Loss of anthocyanins was also measured during oxidation in corn oil-in-water emulsions. In addition, the impact of plant phenolics on amino acid level was studied using tryptophan as a model compound to elucidate their role in preventing the formation of tryptophan oxidation products. A high-performance liquid chromatography (HPLC) method with ultraviolet and fluorescence detection (UV-FL) was developed that enabled fast investigation of formation of tryptophan derived oxidation products. Byproducts of oilseed processes such as rapeseed (Brassica rapa L.), camelina (Camelina sativa) and soy meal (Glycine max L.) as well as Scots pine bark (Pinus sylvestris) and several reference compounds were shown to act as antioxidants toward both protein and lipid oxidation in cooked pork meat patties. In meat, the antioxidant activity of camelina, rapeseed and soy meal were more pronounced when used in combination with a commercial rosemary extract (Rosmarinus officinalis). Berry phenolics such as black currant (Ribes nigrum) anthocyanins and raspberry (Rubus idaeus) ellagitannins showed potent antioxidant activity in corn oil-in-water emulsions toward lipid oxidation with and without β-lactoglobulin. The antioxidant effect was more pronounced in the presence of β-lactoglobulin. The berry phenolics also inhibited the oxidation of tryptophan and cysteine side chains of β-lactoglobulin. The results show that the amino acid side chains were oxidized prior the propagation of lipid oxidation, thereby inhibiting fatty acid scission. In addition, the concentration and color of black currant anthocyanins decreased during the oxidation. Oxidation of tryptophan was investigated in two different oxidation models with hydrogen peroxide (H2O2) and hexanal/FeCl2. Oxidation of tryptophan in both models resulted in oxidation products such as 3a-hydroxypyrroloindole-2-carboxylic acid, dioxindolylalanine, 5-hydroxy-tryptophan, kynurenine, N-formylkynurenine and β-oxindolylalanine. However, formation of tryptamine was only observed in tryptophan oxidized in the presence of H2O2. Pine bark phenolics, black currant anthocyanins, camelina meal phenolics as well as cranberry proanthocyanidins (Vaccinium oxycoccus) provided the best antioxidant effect toward tryptophan and its oxidation products when oxidized with H2O2. The tryptophan modifications formed upon hexanal/FeCl2 treatment were efficiently inhibited by camelina meal followed by rapeseed and soy meal. In contrast, phenolics from raspberry, black currant, and rowanberry (Sorbus aucuparia) acted as weak prooxidants. This thesis contributes to elucidating the effects of natural phenolic compounds as potential antioxidants in order to control and prevent protein and lipid oxidation reactions. Understanding the relationship between phenolic compounds and proteins as well as lipids could lead to the development of new, effective, and multifunctional antioxidant strategies that could be used in food, cosmetic and pharmaceutical applications.

Properties of intramuscular connective tissue in pork and poultry with reference to weakening of structure

The most common connective tissue research in meat science has been conducted on the properties of intramuscular connective tissue (IMCT) in connection with eating quality of meat. From the chemical and physical properties of meat, researchers have concluded that meat from animals younger than physiological maturity is the most tender. In pork and poultry, different challenges have been raised: the structure of cooked meat has weakened. In extreme cases raw porcine M. semimembranosus (SM) and in most turkey M. pectoralis superficialis (PS) can be peeled off in strips along the perimysium which surrounds the muscle fibre bundles (destructured meat), and when cooked, the slices disintegrate. Raw chicken meat is generally very soft and when cooked, it can even be mushy. The overall aim of this thesis was to study the thermal properties of IMCT in porcine SM in order to see if these properties were in association with destructured meat in pork and to characterise IMCT in poultry PS. First a 'baseline' study to characterise the thermal stability of IMCT in light coloured (SM and M. longissimus dorsi in pigs and PS in poultry) and dark coloured (M. infraspinatus in pigs and a combination of M. quadriceps femoris and M. iliotibialis lateralis in poultry) muscles was necessary. Thereafter, it was investigated whether the properties of muscle fibres differed in destructured and normal porcine muscles. Collagen content and also solubility of dark coloured muscles were higher than in light coloured muscles in pork and poultry. Collagen solubility was especially high in chicken muscles, approx. 30 %, in comparison to porcine and turkey muscles. However, collagen content and solubility were similar in destructured and normal porcine SM muscles. Thermal shrinkage of IMCT occurred at approximately 65 °C in pork and poultry. It occurred at lower temperature in light coloured muscles than in dark coloured muscles, although the difference was not always significant. The onset and peak temperatures of thermal shrinkage of IMCT were lower in destructured than in normal SM muscles, when the IMCT from SM muscles exhibiting ten lowest and ten highest ultimate pH values were investigated (onset: 59.4 °C vs. 60.7 °C, peak: 64.9 °C vs. 65.7 °C). As the destructured meat was paler than normal meat, the PSE (pale, soft, exudative) phenomenon could not be ruled out. The muscle fibre cross sectional area (CSA), the number of capillaries per muscle fibre CSA and per fibre and sarcomere length were similar in destructured and normal SM muscles. Drip loss was clearly higher in destructured than in normal SM muscles. In conclusion, collagen content and solubility and thermal shrinkage temperature vary between porcine and poultry muscles. One feature in the IMCT could not be directly associated with weakening of the meat structure. Poultry breast meat is very homogenous within the species.

Diet, cell signalling, and tumourigenesis in multiple intestinal neoplasia mice

The incidence of colon cancer is high in Western societies, and in Finland it is among the three most common cancer types in both females and males. Environmental factors, including diet, affect colon cancer development. During the last few years, a vast amount of new, functional foods have been introduced to the consumers. Several products are already available that are marketed as promoting intestinal health. To be able to reliably call a dietary compound a chemopreventive substance it is of fundamental importance to understand the mechanism by which it affects tumour formation and the integrity of the epithelial cells. In this thesis, three different dietary compounds were studied in an experimental model of colon cancer. Inulin is a non-digestible fibre found naturally in chicory roots, artichokes and onions, amongst others. Nowadays it is widely used as an added dietary fibre in several food products. Conjugated linoleic acid (CLA) is a conjugated form of the fatty acid linoleic acid. CLA is formed by bacterial fermentation of linoleic acid in the rumen of cows and other ruminants. Concomitantly, it can naturally be found in milk and meat of ruminants. White currant is a colourless berry low in phenolic compounds that are believed to prevent cancer formation. Contrary to what was expected, inulin and the conjugated linoleic acid isomer trans-10, cis-12, were tumour growth promoting dietary constituents when fed to Min mice. Both diets decreased the NF-kappaB levels in the mucosa, but physiological adenoma development did not affect NF-kappaB. Diet altered beta-catenin and p53 signalling in the adenomas, confirming their involvement in adenoma growth. White currant, on the other hand, was chemopreventive, despite its low contents of phenolic compounds. The chemopreventive effect was accompanied by increased p53 levels in the mucosa, and decreased beta-catenin and NF-kappaB levels in the adenoma. This could explain the reduced adenoma number and size. The results underline the importance of carefully testing new dietary compounds in different settings to reliably confirm their health benefits. In this study two compounds that are consumed and believed to add to our health proved to be cancer promotive. A berry with low phenolic contents, on the other hand, was chemopreventive.

Assessment and control of Bacillus cereus emetic toxin in food

Despite of improving levels of hygiene, the incidence of registered food borne disease has been at the same level for many years: there were 40 to 90 epidemics in which 1000-9000 persons contracted food poisoning through food or drinking water in Finland. Until the year 2004 salmonella and campylobacter were the most common bacterial causes of food borne diseases, but in years 2005-2006 Bacillus cereus was the most common. Similar developement has been published i.e. in Germany already in the 1990´s. One reason for this can be Bacillus cereus and its emetic toxin, cereulide. Bacillus cereus is a common environmental bacterium that contaminates raw materials of food. Otherwise than salmonella and campylobacter, Bacillus cereus is a heat resistant bacterium, capable of surviving most cooking procedures due to the production of highly thermo resistant spores. The food involved has usually been heat treated and surviving spores are the source of the food poisoning. The heat treatment induces germination of the spore and the vegetative cells then produce toxins. This doctoral thesis research focuses on developing methods for assessing and eliminating risks to food safety by cereulide producing Bacillus cereus. The biochemistry and physiology of cereulide production was investigated and the results were targeted to offer tools for minimizing toxin risk in food during the production. I developed methods for the extraction and quantitative analysis of cereulide directly from food. A prerequisite for that is knowledge of the chemical and physical properties of the toxin. Because cereulide is practically insoluble in water, I used organic solvents; methanol, ethanol and pentane for the extraction. For extraction of bakery products I used high temperature (100C) and pressure (103.4 bars). Alternaties for effective extraction is to flood the plain food with ethanol, followed by stationary equilibration at room temperature. I used this protocol for extracting cereulide from potato puree and penne. Using this extraction method it is also possible also extract cereulide from liquid food, like milk. These extraction methods are important improvement steps for studying of Bacillus cereus emetic food poisonings. Prior my work, cereulide extraction was done using water. As the result, the yield was poor and variable. To investigate suspected food poisonings, it is important to show actual toxicity of the incriminated food. Many toxins, but not cereulide, inactivate during food processing like heating. The next step is to identify toxin by chemical methods. I developed with my colleague Maria Andesson a rapid assay for the detection of cereulide toxicity, within 5 to 15 minutes. By applying this test it is possible to rapidly detect which food was causing the food poisoning. The chemical identification of cereulide was achieved using mass spectrometry. I used cereulide specific molecular ions, m/z (+/-0.3) 1153.8 (M+H+), 1171.0 (M+NH4+), 1176.0 (M+Na+) and 1191.7 (M+K+) for reliable identification. I investigated foods to find out their amenability to accumulate cereulide. Cereulide was formed high amounts (0.3 to 5.5 microg/g wet wt) when of cereulide producing B. cereus strains were present in beans, rice, rice-pastry and meat-pastry, if stored at non refrigerated temperatures (21-23C). Rice and meat pastries are frequently consumed under conditions where no cooled storage is available e.g. picnics and outdoor events. Bacillus cereus is a ubiquitous spore former and is therefore difficult to eliminate from foods. It is therefore important to know which conditions will affect the formation of cereulide in foods. My research showed that the cereulide content was strongly (10 to 1000 fold differences in toxin content) affected by the growth environment of the bacterium. Storage of foods under nitrogen atmosphere (> 99.5 %) prevented the production of cereulide. But when also carbon dioxide was present, minimizing the oxygen contant (< 1%) did not protect the food from formation of cereulide in preliminary experiments. Also food supplements affected cereulide production at least in the laboratory. Adding free amino acids, leucine and valine, stimulated cereulide production 10 to 20 fold. In peptide bonded form these amino acids are natural constituents in all proteins. Interestingly, adding peptide bonded leucine and valine had no significant effect on cereulide production. Free amino acids leucine and valine are approved food supplements and widely used as flawour modifiers in food technology. My research showed that these food supplements may increase food poisoning risk even though they are not toxic themselves.