| 1. |
- Forssén, K M, et al.
(författare)
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Folates and dairy products : a critical update.
- 2000
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Ingår i: Journal of the American College of Nutrition (Print). - 0731-5724 .- 1541-1087. ; 19:2 Suppl, s. 100S-110S
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, folates have come into focus due to their protective role against child birth defects, for example, neural tube defects. In addition, folates may have a protective role to play against coronary heart disease and certain forms of cancer. During the last few years most countries have established increased recommended intakes of folates, for example, between 300-400 microg per day for adults. This review of folates in milk and dairy products compares some recent data based on high pressure liquid chromatography (HPLC) analyses and radioprotein-binding assays, with previous data based on microbiological assays. All three methods show similar ranges for folates in cow's milk, 5-10 microg per 100 g, the variation being due to seasonal variations. Data on folates in fermented milk (buttermilk and yogurt) are also similar for these methods. Different starter cultures, however, might explain some of the variations in folate content and folate forms. Most cheese varieties contain between 10 microg and 40 microg folate per kg, with slightly higher values for whey cheese. Ripened soft cheeses may contain up to 100 microg folate per 100 g. Most previous and recent studies using HPLC indicate that 5-methyl-tetrahydrofolate (5-methyl-THF) is the major folate form in milk, but more studies are needed concerning folate forms in other, especially fermented dairy products. Relatively new data on actual concentrations in different dairy products show folate-binding proteins (FBP) to occur in unprocessed milk, but also in pasteurised milk, spray-dried skim milk powder and whey. In contrast, UHT milk, fermented milk and most cheeses only contain low levels or trace amounts.
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| 2. |
- Johannesson, Lena M, et al.
(författare)
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Folate content in strawberries - Effects of storage, ripeness and cultivar
- 2002
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Ingår i: Acta Horticulturae. ; 567, s. 809-812
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Tidskriftsartikel (refereegranskat)abstract
- Strawberries are a good dietary source of folate and are of interest because of their importance as raw material for the Swedish food industry. The aim of this study was to quantify the total folate content in strawberries, after different conditions of storage, at different grades of ripeness and in different cultivars, using a strictly controlled RPBA-kit, optimised for food analysis. In the study fresh strawberries were stored imitating commercial conditions no losses of folate could be observed. Regarding ripeness, the highest folate concentration was found in unripe strawberries, which differed significantly from ripe and overripe. A significant variation (p<0.01) was found for six different cultivars. All results are given for both fresh and dry matter in order to exclude interference from possible variations in water content.
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| 3. |
- Lingnert, H, et al.
(författare)
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Acrylamide in food: mechanism of formation and influencing factors during heating of foods
- 2002
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Ingår i: Scandinavian Journal of Food and Nutrition. - : Informa UK Limited. - 1748-2976. ; 46:4, s. 159-172
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Tidskriftsartikel (refereegranskat)abstract
- Background: In April 2002, the Swedish National Food Administration and a scientific group at the University of Stockholm jointly announced that they had shown acrylamide to be formed during the preparation of food and found it to occur in many foodstuffs. These new findings were clearly of concern to many types of industrial food processing as well as to home cooking. The Swedish Food Federation (Li) initiated and financed the formation of an expert committee to look into the chemical mechanisms. The present review is the final report of that expert committee. Design: The study identified, examined and put together facts and present knowledge on reaction routes for acrylamide formation in food and causal connections to cooking and food processing conditions. The results are based on literature surveys, examination of the analytical data published by the Swedish National Food Administration and other follow-up studies, contacts with international scientific networks, and observations from food companies. Results: The exact chemical mechanism(s) for acrylamide formation in heated foods is unknown. Several plausible mechanistic routes may be suggested, involving reactions of carbohydrates, proteins/amino acids, lipids and probably also other food components as precursors. With the data and knowledge available today it is not possible to point out any specific routes, or to exclude any possibilities. It is likely that a multitude of reaction mechanisms is involved. Acrolein is one strong precursor candidate, the origin of which could be lipids, carbohydrates or proteins/amino acids. Acrylamide is a reactive molecule and it can readily react with various other components in the food. The actual acrylamide level in a specific food product, therefore, probably reflects the balance between ease of formation and potential for further reactions in that food matrix. There are indications in support of that the Maillard reaction being an important reaction route for acrylamide formation, but lipid degradation pathways to the formation of acrolein should also be considered. Conclusions: Reliable analytical methods to measure acrylamide in foods are available. Model studies are needed to identify precursors and reaction route(s) based on current hypotheses and to elucidate possible further reactions between acrylamide and other food components. Studies are needed to optimize formulation and processing conditions to minimize acrylamide levels, taking other product quality properties into consideration.
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| 4. |
- Strålsjö, Lena M, et al.
(författare)
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Folate content in strawberries (Fragaria x ananassa) : effects of cultivar, ripeness, year of harvest, storage, and commercial processing.
- 2003
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 51:1, s. 128-133
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Tidskriftsartikel (refereegranskat)abstract
- Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day).
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| 5. |
- Arkbåge, Karin, et al.
(författare)
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Retention of vitamin B-12 during manufacture of six fermented dairy products using a validated radio protein-binding assay
- 2003
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Ingår i: International Dairy Journal. - 0958-6946 .- 1879-0143. ; 13:2-3, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to study vitamin B-12 retention during manufacture of six fermented dairy products. Careful validation of a commercial radio protein-binding kit showed this assay to be suitable after optimisation of sample pre-treatment and control of the kit for possible matrix effects. In fermented milks, vitamin B-12 concentrations decreased by 40-60%, compared with the starting milk, during storage of the final product at 4degreesC for 14 days, most likely attributed to consumption by starter cultures. In cottage cheese, hard cheeses and blue cheese, 18-56% of the vitamin B-12 originally present in the milk was retained. Removal of the whey fraction was the dominant factor reducing vitamin B-12 retention in cheeses, while the fermentation by starter cultures hardly affected vitamin B-12 concentrations.
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| 6. |
- Johansson, Madelene, et al.
(författare)
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Study of wheat breakfast rolls fortified with folic acid : The effect on folate status in women during a 3-month intervention
- 2002
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Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6207 .- 1436-6215. ; 41:6, s. 279-286
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Folate has come into focus due to its protective role against child birth defects such as neural tube defects (NTD). Swedish authorities recommend all fertile women to increase their folate intake to 400 microg/day by eating folate-rich foods. Because not all women follow these recommendations, there is a discussion today about whether Sweden should introduce folic acid fortification in wheat flour and sifted rye flour. This decision needs knowledge about the bioavailability of folic acid from fortified foods.AIM OF THE STUDY: To investigate effects of two folic acid fortification levels on folate status in healthy female volunteers and to study the folic acid stability during the baking procedure and storage of the fortified breakfast rolls.METHOD: Twenty-nine healthy women were recruited. Folic acid-fortified wheat breakfast rolls were baked with the purpose to contain 200 microg folic acid/roll (roll L) and 400 microg folic acid/roll (roll H). Fourteen women were given one roll/day of roll L (group L) and 15 one roll/day of roll H (group H) during 12 weeks of intervention. Fasting venous blood samples were collected on days 0, 30, 60 and 90. Serum homocysteine concentrations were determined using an immunoassay. Serum and erythrocyte folate concentrations were analysed using a protein-binding assay with fluorescent quantification. The folic acid concentration in the breakfast rolls was analysed by HPLC on days 0, 30, 60 and 90. Total folate concentration was measured with microbiological assay on day 45.RESULTS: Group L Group L had initially an average erythrocyte folate concentration of 577 +/- 93 nmol/L. After 90 days of intervention, an increase of 20 % (p < 0.05) was observed. At day 0, mean serum folate concentrations were 16.9 +/- 4.3 nmol/L. The mean serum folate concentrations increased by 30 % (p < 0.001) after 90 days. At day 0, mean serum homocysteine concentrations were 9.1 +/- 2.0 micromol/L, which decreased by 20 % (p < 0.01) after 30 days. Group H Group H had an initial erythrocyte folate concentration of 784 +/- 238 nmol/L. After 90 days, an increase of 26 % (p < 0.05) was observed. Serum folate increased at least 22 % after 30 days, from a level of 18.7 +/- 4.8 nmol/L at day 0. Thereafter, all women of group H had serum concentrations at or above the upper limit of quantification (23 nmol/L). At day 0, mean serum homocysteine concentrations were 8.4 +/- 1.7 micromol/L, which decreased by 16 % (p < 0.05) after 30 days. The baking procedure resulted in 20-25 % loss of fortified folic acid in the rolls used in the present study. The size of the rolls affected the retention of folic acid during baking. No significant loss was seen in folic acid concentration in the rolls during the intervention period.CONCLUSION: The present study showed that in healthy women, subjected to a 12-week intervention with breakfast rolls fortified with either 166 microg or 355 microg folic acid, serum homocysteine concentration decreased (p < 0.05) and erythrocyte folate increased (p < 0.05). The lower level of fortification seems to be sufficient to improve the folate status. Together with the average daily intake of natural folates, these women reach the recommended intake of 400 microg/day. Folic acid is stable in fortified bread for 90 days storage at -20 degrees C.
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| 7. |
- Sjödin, P, et al.
(författare)
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Effect of dietary fiber on the disposition and excretion of a food carcinogen (2-14C-labeled MeIQx) in rats
- 1992
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Ingår i: Nutrition and Cancer. - : Informa UK Limited. - 0163-5581 .- 1532-7914. ; 17:2, s. 139-151
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Tidskriftsartikel (refereegranskat)abstract
- We studied to what extent dietary fiber may affect uptake, retention, and excretion of a food carcinogen (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, MeIQx) occurring in fried meat. Four diets--one fiber-free control and three containing either insoluble dietary fiber isolated from sorghum (100 g/kg) and wheat bran (100 g/kg) or the highly soluble pectin (50 g/kg)--were investigated. The fiber diets were given in amounts of 10 g/day to rats. Thus, each rat received 1 or 0.5 g fiber and 100 micrograms 2-14C-labeled MeIQx uniformly mixed in its daily diet. A 4-day adaptation period with unlabeled MeIQx was followed by a 5-day experimental period with 14C-labeled MeIQx, during which urine and feces were collected separately for analysis of radioactivity and mutagenicity. Furthermore the composition and the fermentability of the dietary fiber were determined. The present study shows that a diet containing fiber, especially fiber isolated from sorghum and wheat bran, affects the excretion pattern of the food carcinogen MeIQx in a manner suggesting a lower uptake and a decreased transit time through the gastrointestinal tract in a more diluted form than a nonfiber diet. Furthermore, less radioactivity was retained in the kidneys with sorghum and wheat bran than with the other two diets. On the other hand, none of these types of dietary fiber affected the retention of the hepatocarcinogen MeIQx in the liver 24 hours after the last oral intake. DNA adducts were formed to a higher extent in the kidney than in the liver. The highest levels were found in animals given the wheat bran diet.
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| 8. |
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| 9. |
- Strålsjö, Lena, et al.
(författare)
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Evaluation of a radioprotein-binding assay (RPBA) for folate analysis in berries and milk
- 2002
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Ingår i: Food Chemistry. - 0308-8146 .- 1873-7072. ; 79:4, s. 525-534
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to optimise a commercial radioprotein-binding assay (RPBA), routinely used for clinical samples, for folate quantification in foods containing mainly 5-CH3-H(4)folate. The assay was modified using external calibration with 5-CH3-H(4)folate in a lower concentration range diluted in food extraction buffer, rather than the buffer with human serum albumin (HSA) provided by the kit. We evaluated the modified RBPA on some selected food products; milk, whey powder, rose hips, strawberries and European certified reference materials (CRM 421, 485) and the adjustments did not affect the assay negatively. Performance parameters included control of selectivity, absence of matrix effects, recoveries of 94-113%, precision of 1-6 CV% (intra-assay) and 5-9 CV% (inter-assay). Folate concentrations in berries and milk, obtained by the modified RPBA were also compared with other quantification methods such as HPLC and MA. The optimised RPBA was found to be a quick and inexpensive complement to HPLC methods, reliable for folate quantification in foods such as milk and berries that contain mainly 5-CH3-H(4)folate. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 10. |
- Witthöft, Cornelia M., et al.
(författare)
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Folate content and bioavailability in food using HPLC-methods and a human model
- 1999
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Ingår i: VITAMINE UND ZUSATZSTOFFE IN DER ERNAHRUNG VON MENSCH UND TIER. - Jena. ; , s. 109-114
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Konferensbidrag (refereegranskat)abstract
- Methods for the extraction, stabilization, deconjugation, purification and subsequent HPLC determination of folates from biological material were presented. All methods were externally validated by participation in European intercomparison studies. They were successfully applied to determine folate concentrations in food and human plasma for biokinetical purposes.
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