Terje Tamme

Polycyclic aromatic hydrocarbons (PAHs) in meat products and estimated PAH intake by children and the general population in Estonia

The concentrations of benzo[a]pyrene and 11 other polycyclic aromatic hydrocarbons (PAHs) were analysed from 322 commercial, cured meat products and 14 home-grilled meat samples as part of the Estonian food safety monitoring programme during 2001–2005. The maximum acceptable concentration of 5 µg kg−1 for benzo[a]pyrene was exceeded in 3.4% of samples. The highest PAH concentrations were detected in home-grilled pork samples. Using of disposable grilling unit resulted in 1.6 times higher PAH concentrations compared to the traditional wood-burning grill. The average intake of benzo[a]pyrene and sum of 12 PAHs from meat products was estimated for children (age 1–16 years) on the basis of an individual food consumption questionnaire and, for the general population, based on national food consumption data. The highest total PAH concentrations detected were 16 µg kg−1 in smoked meat and ham, 19 µg kg−1 in smoked sausage and 6.5 µg kg−1 in smoked chicken samples. Since smoking and grilling are prevalent meat-cooking methods in Estonia, the impact of meat products is assessed to be significant in overall PAH intake.

Nitrates and nitrites in vegetables and vegetable-based products and their intakes by the Estonian population

The content of nitrates were determined in 1349 samples of vegetables and ready-made food in 2003–2004 as a part of the Estonian food safety monitoring programme and the Estonian Science Foundation grant research activities. The results of manufacturers’ analyses carried out for internal monitoring were included in the study. The highest mean values of nitrates were detected in dill, spinach, lettuce and beetroot. The mean concentrations were 2936, 2508, 2167 and 1446 mg kg−1, respectively. The content of nitrites in samples was lower than 5 mg kg−1. In total, the mean intake of nitrates by the Estonian population was 58 mg day−1. The mean content of nitrates in vegetable-based infant foods of Estonian origin was 88 mg kg−1. The average daily intake of nitrates by children in the age group of 4–6 years was 30 mg. The infants’ average daily intake of nitrates from consumption of vegetable-based foods was 7.8 mg.

Nitrites, nitrates and N-nitrosoamines in Estonian cured meat products: Intake by Estonian children and adolescents

The contents of nitrate, nitrite and N-nitrosoamines in commercial cured meat products on the Estonian market were determined for 2000–01 and 2003–04 as part of the Estonian food safety monitoring programme and the Estonian Science Foundation grant research activities. The maximum permitted levels of residual nitrites and nitrates were not exceeded in the samples analysed. However, a great variation in the content of nitrate, nitrite and N-nitrosoamines was found for all the products. The concentrations of these compounds in domestic cured meat products showed a decrease from year to year. The mean intake of nitrate, nitrite and N-nitrosoamines by Estonian children (n = 346) from cured meat products was calculated on the basis of individual intake data. The mean daily intake of nitrates was 1.7 mg, that of nitrites was 0.83 mg and that of N-nitrosoamines was 0.073 µg. In the 2000–01 study, the calculated nitrite intake exceeded the acceptable daily intake by up to 140% for 1–6-year-old children and up to 105% in 2003–04.

High level of antimicrobial resistance in Campylobacter jejuni isolated from broiler chickens in Estonia in 2005 and 2006.

The development of antimicrobial resistance in Campylobacter jejuni and Campylobacter coli is a matter of increasing concern. Because campylobacteriosis is transmitted to humans usually via food of animal origin, the presence of antimicrobial-resistant campylobacters in broiler chickens has important public health implications. The aim of our study was to analyze resistance patterns of C. jejuni isolated from fecal samples collected at a large Estonian chicken farm, from cecal contents collected at slaughterhouses, and from meat samples collected at the retail establishments in 2005 and 2006. A total of 131 C. jejuni isolates were collected over a 13-month period and tested by the broth microdilution VetMIC method (National Veterinary Institute, Uppsala, Sweden) to determine the MICs of various antimicrobials. Resistance to one or more antimicrobials was detected in 104 (79.4%) of the 131 isolates. High proportions of the isolates were resistant to enrofloxacin (73.3%) and nalidixic acid (75.6%). Multidrug resistance (resistance to three or more unrelated antimicrobials) was detected in 36 isolates (27.5%), all of which were resistant to enrofloxacin. Multidrug resistance was significantly associated with enrofloxacin resistance (P < 0.01), and the use of enrofloxacin may select for multiresistant strains.

Nitrates and Nitrites in Vegetables: Occurrence and Health Risks

Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.

Dynamics of nitrate and nitrite content during storage of home-made and small-scale industrially produced raw vegetable juices and their dietary intake

The influence of storage conditions on nitrate and nitrite contents, pH, and total viable bacterial count of raw vegetable juices was studied. Three different types of juices from an Estonian small-scale producer and five different types of home-made juices were analysed. Analyses were performed immediately after opening the commercial juice packages and immediately after preparation of a home-made juice. Additionally, samples were taken after open storage of a juice at the refrigerator and ambient temperatures during 24 and 48 h. The biggest changes in nitrate and nitrite contents were found during storage of carrot, beetroot and radish juices. During 48 h of storage at ambient temperature, the mean increases of nitrite content in home-made carrot, beetroot and radish juices were from 0.1 to 187, from 2.1 to 578, and from 0.5 to 259 mg l−1, respectively. In the case of commercial lightly pasteurized products, the biggest increase of nitrite content, from 3.2 to 11 mg l−1, was found in red beetroot juice. After 48 h of storage at refrigerator temperature, the changes of nitrite and nitrate were smaller. In the case of consumption of 300 ml of home-made carrot juice, with a nitrate and nitrite content of 64 and 110 mg l−1, respectively, stored for 24 h at ambient temperature, the average intake was 8% and 846% of the acceptable daily intake of nitrates and nitrites, respectively. After consumption of 50 ml of the same carrot juice by children (1–2 years of age) the average intake of nitrates and nitrites was 7% and 733% of the acceptable daily intake, respectively.

Nitrate in leafy vegetables, culinary herbs, and cucumber grown under cover in Estonia: content and intake

The content of nitrate in leafy vegetables, culinary herbs, and cucumber was determined during the years 2006–2008. All samples of Estonian origin, except white cabbage, were grown under cover. Seasonal differences in nitrate concentrations were observed in lettuce and spinach. Nitrate concentrations in lettuce were 22% and those in spinach were 24% higher in winter crops compared with samples collected in summer. The mean nitrate level was 3023 mg kg–1 for fresh lettuce and 2337 mg kg–1 for spinach. On average, 11.6% of fresh lettuce and spinach samples nitrate concentration exceeded the maximum level specified in European Commission Regulation No. 1881/2006. The mean levels were 999 mg kg–1 for imported iceberg lettuce and 1287 mg kg–1 for frozen spinach, which are below the maximum European Commission limits. Parsley, dill, basil, thyme, and rucola contained high concentrations of nitrate from mean levels of 2134 mg kg–1 for parsley up to 8150 mg kg–1 for rucola. Mean nitrate concentrations ranged from 382 to 1115 mg kg–1 for white cabbage and Chinese cabbage, respectively. The per capita mean daily intake of nitrates related to the consumption of leafy vegetables, culinary herbs, and cucumber for the whole Estonian population was 31.3 mg day–1, which comprised 14.2% of the acceptable daily intake (ADI).

Nitrates and Nitrites in Vegetables

Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.

Impact of Food Processing and Storage Conditions on Nitrate Content in Canned Vegetable-Based Infant Foods

The nitrate and nitrite contents were determined in canned vegetable-based infant foods of five varieties. Furthermore, changes in nitrate content during industrial processing were studied. Samples were taken from raw materials, homogenized mixtures, and final products after sterilization, and then analyzed for nitrate and nitrite content by high-pressure liquid chromatography. Processing steps preceding heat treatment, such as vegetable peeling and washing, decreased the nitrate concentrations in the range of 17 to 52%. During processing, the nitrate content in canned infant foods decreased 39 to 50%, compared with nitrate concentration in the raw-vegetable mixture. The final nitrate concentration in infant foods depends mainly on the initial nitrate content of the raw-vegetable mixture. The effect of storage time (24 and 48 h) and temperature (4 to 6 degrees C and 20 to 22 degrees C) on nitrate and nitrite content in opened canned infant-food samples was studied. After 24 h of storage at refrigerated and room temperatures, the mean nitrate content increased on average by 7 and 13%, and after 48 h of storage by 15 and 29%, respectively. The nitrite content in all analyzed samples was below the quantification limit. Storage requirements of industrial manufacturers must be followed strictly. Opened can foods, stored under refrigerated conditions, have to be consumed within 2 days, as recommended by manufacturers. The infant-food producers must pay more attention to the quality of raw materials. Nitrate content analyses should be added as compulsory tests to the quality assurance programs.

Chapter 21 – Nitrates and Nitrites in Vegetables: Occurrence and Health Risks

Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.Publisher Summary The gaseous form of nitrogen makes up 78% of the troposphere. Its incorporation into terrestrial nitrogenous compounds takes place via different pathways, including microorganisms, plants, and human industrial and agricultural activities. Nitrogen taken from the air is converted to ammonia by nitrogen-fixing bacteria. In most soils, ammonium is rapidly oxidized to nitrite and, consequently, into nitrate in a nitrification process by the action of the aerobic bacteria, such as Nitrosomonas and Nitrobacter. The nitrate ion is the stable form of nitrogen for oxygenated systems. Nitrate is very soluble and, unless intercepted or taken up by plant roots, leaches down into the soil along with irrigation or rainwater or is carried away by runoff. Nitrate and nitrite occur in drinking water mainly as a result of intensive agricultural activities. Nitrate-containing compounds present in soil are generally soluble and readily migrate into groundwater. Contamination of soil with nitrogen-containing fertilizers, including anhydrous ammonia, as well as animal or human natural organic wastes, can raise the concentration of nitrate in water. As nitrite is easily oxidized to nitrate, nitrite levels in water are usually low, and nitrate is the compound predominantly found in groundwater and surface waters. Being an essential element for plant growth, nitrogen is absorbed by plants in the form of ammonium or nitrate from soil water. Nitrates accumulated in plants form a nitrogen reserve, which is needed for amino acid and protein synthesis. All nitrates absorbed by plant roots are reduced once inside the plant to form ammonia, which serves as a precursor for protein synthesis. Every reduction step is catalyzed by a certain enzyme-reductase.