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Determinants of wheat antigen and fungal alpha-amylase exposure in bakeries.

The study's objectives were to measure flour antigen exposure in bakeries and define the determinants of exposure. Ninety-six bakery workers, employed in seven different bakeries, participated in the study. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. The flour antigen exposure was measured as wheat antigen and fungal alpha-amylase content of the water-soluble fraction of inhalable dust, assayed via enzyme-linked immunosorbent assays. During the entire sampling period bakers were observed and information on 14 different tasks was recorded at 15-minute intervals. Other production characteristics were also recorded for each sampling day and used in statistical modeling to identify significant predictors of exposure. The mean alpha-amylase antigen exposure was 22.0 ng/m3 (ranging from below the limit of detection of 0.1 ng/m3 to 307.1 ng/m3) and the mean wheat antigen exposure was 109 micrograms/m3 (ranging from below the limit of detection of 1 microgram/m3 to 1018 micrograms/m3). Regression models that explained 74% of variability in wheat antigen and alpha-amylase antigen exposures were constructed. The models indicated that tasks such as weighing, pouring, and operating dough-brakers increased flour antigen exposure, while packing and decorating resulted in lower exposures. Croissant, puff-pastry, and bread/bun production lines were associated with increased exposure, while cake production and substitution of dusting with the use of divider oil were associated with decreased exposure. Exposure levels can be reduced by the automation of forming tasks, alteration of tasks requiring pouring of flour, and changes to the types of products manufactured.

Air Pollutants, Occupational↗

Thermal and physical properties of bakery products.

This article reviews the measurement techniques, prediction models, and data on thermo-physical properties of bakery products: specific heat, thermal conductivity, thermal diffusivity, and density. Over the last decade, investigation has focused more on thermo-physical properties of nonbread bakery products. Both commonly used and new measurement techniques for thermo-physical properties reported in the publication are presented with directions for their proper use. Data and prediction models are tabulated for the range of moisture content and temperature of the bakery products.

Bread↗

Characterization of exposure to inhalable flour dust in Swedish bakeries.

Bakery workers are at risk of developing respiratory symptoms, such as asthma and rhinitis. Exposure to inhalable flour dust in 12 Swedish bakeries was therefore determined: concentrations of airborne inhalable flour dust were measured with the IOM personal inspirable dust sampler and the particle size distribution assessed using the IOM personal inspirable aerosol spectrometer, and the fractions of alpha-amylase, water-soluble protein and total protein in flour dust were determined. A total of 129 measurements were performed of which 77 were repeated measurements. There was a clear hierarchy in geometric mean exposure among bakery workers, with in descending order doughmakers (5.46 mg m-3), bread-formers (2.69 mg m-3), oven workers (1.17 mg m-3), and packers and confectionery workers (0.53 mg m-3). The repeated measurements revealed that within each task group there were considerable differences in mean exposure among the workers: this was demonstrated by geometric standard deviations of between-worker variance of 1.63-1.77. Partitioning of the total variability of inhalable flour dust exposure showed that the task group was the principal source of variance, accounting for 61-69% of the total variability. The optimum grouping strategy was independent of whether the oven workers and the packers were assigned to the same or to different task groups. The doughmakers and the bread-formers are two clearly distinguishable exposure groups with largely overlapping exposure distributions. On average, the flour dust contained 9% total protein, 2.3% water-soluble protein and 0.03% alpha-amylase. The inhalable flour dust was characterized by a substantial proportion of particles with a d(ac) above 10 microns. It was estimated that the thoracic subfraction contributed 39% to the total mass of inhalable dust, and the respirable subfraction 19%.

Dust↗

[Enrichment of wheat flour with sunflower and soya flour for bakery products].

In order to improve the nutritive value of wheat protein, with a wheat flour, defated soybean flour and sunflower seed flour were mixed on the basis of their amino acid composition. The highest nutritive value, 86 expressed as CS, was obtained with 60% wheat flour + 28% defatted soybean flour + 12% defatted sunflower seed flour. The mixture was used to prepare: a) sea-biscuits, baked in a traditional bakery oven, and b) crackers, baked in an electric endless oven. Similar products, baked with wheat flour alone, were studied as controls. Chemical composition, total lysine, methionine, cystine, threonine and available lysine content were determine on the raw flours and mixture. Protein, fats and available lysine were determined on the bakery products. The nutritive value of the latter was assessed by their NPUop from which NPUst was calculated. The results showed an increase in the protein content of the enriched bakery products up to 60% over the controls. The nutritive value of the products was lower than the calculated figure for the raw mixture. Products b had the highest NPUst (56.4), surpassing the figures for the control (33.3) and also for product a (53.5). These values agreed with the figures for lysine availability which decreased with heat according to the cooking process. These data and the good acceptability of the crackers suggest that their enrichment with soybean and sunflowers seed concentrates asayed, could help to fulfill protein requirements in children.

Amino Acids↗

The use of dried bakery products in a free-choice feeding method for small-scale broiler production.

Waste material from bakeries is an unconventional energy feed source which is available in sufficient quantities for use in small-scale broiler production in South Africa. Small-scale broiler producers do not have access to the computer programs required to balance home-mixed rations. This investigation confirms that the use of dried bakery products (DBP) in a 2-stage, free-choice method can be used to compensate for this lack. A total of 570 day-old male broiler chickens was assigned to 3 feeding treatments: the control group was fed a 2-stage feeding programme using standard commercial starter and grower rations. The 2nd group received a commercial starter ration up to Day 7 and was thereafter given a choice of a commercial starter ration with normal salt content (0.35%) and DBP. The 3rd group was fed a commercial starter ration up to Day 7, then offered a choice of commercial starter ration with a lower salt content (0.1%) and DBP. The low salt alternative was used to test whether the higher salt percentage in DBP influenced the choice of feed by the birds. It was found that the control group consumed significantly more feed (P < 0.05) and was significantly heavier (P < 0.05) than the experimental groups. However, there was no significant difference between the 2 experimental groups, which indicated that salt content did not play a role in the choice of ration. Feed consumption by both experimental groups was about one-third less than the control group, but the profit margin, as calculated using gross margin analysis, was approximately 15 % higher. It was therefore concluded that dried bakery products can be profitably incorporated as an energy feed source, using the free-choice feeding method, in small-scale broiler enterprises.

Animal Feed↗

Effect of feeding food waste-broiler litter and bakery by-product mixture to pigs.

This study was conducted to evaluate the effects of feeding aerobically processed and vacuum-dried food waste-broiler litter and bakery by-product mixture to finishing pigs on performance, carcass characteristics, meat quality and taste panel test. A corn-soy diet (Control) was replaced with food waste mixture (FWM) at dietary levels of 25% (25% FWM) and 50% (50% FWM) on a dry matter (DM) basis. Diets were fed to a total of 45 pigs (mean body weight 69.4kg) during the eight wk of finishing period. After slaughtering, longissmus muscle at 24h postmortem was used for meat quality analysis. Restaurant food waste was high in protein (22.0%) and fat (23.9%). Supplementing a corn-soy diet with FWM increased (P<0.05) feed DM intake, did not alter (P>0.05) average daily gain, decreased (P<0.05) feed efficiency especially for 50% FWM treatment, and substantially reduced (P<0.05) feed cost, compared with feeding a corn-soy diet only. Feeding FWM up to 50% did not affect (P>0.05) carcass characteristics (carcass weight, dressing percentage, backfat thickness and carcass grade), meat fatty acid composition, meat quality (marbling score, pH, water holding capacity, drip loss, L*, a*, b* values, Warner-Bratzler shear force, cooking loss), and taste panel test (flavor, taste, tenderness, juiciness, and overall acceptance) compared with feeding a corn-soy diet. However, meat color was paler (P<0.05) for 50% FWM fed animals than a corn-soy diet fed animals. Meat color was the only limiting factor when FWM was fed to finishing pigs. In conclusion, aerobically processed and vacuum-dried food waste-broiler litter and bakery by-product mixture was similar to a corn-soy diet in feed value for finishing pigs.

Animal Feed↗

Effect of weak acid preservatives on growth of bakery product spoilage fungi at different water activities and pH values.

Inhibition of spoilage organisms from bakery products by weak acid preservatives in concentrations of 0%, 0.003%, 0.03% and 0.3% (w/v) was investigated experimentally on a substrate media with water activity (a(w)) and pH ranging from sourdough-fermented acidic rye bread to alkaline intermediate moisture sponge cake types (a(w) 0.80-0.95, pH 4.7-7.4). Initially, rye bread conditions (a(w) 0.94-0.97 and pH 4.4-4.8) in combination with calcium propionate were investigated. Results showed that the highest concentration of propionate (0.3%) at all conditions apart from high a(w) (0.97) and high pH (4.8) totally inhibited fungal growth for a 2-week period, with the exception of Penicillium roqueforti, Penicillium commune and Eurotium rubrum. Characteristically for the major spoiler of rye bread, P. roqueforti, all three isolates tested were stimulated by propionate and the stimulation was significantly enhanced at high water activity levels. The effect of propionate on production of secondary metabolites (mycophenolic acid, rugulovasine, echinulin, flavoglaucin) was also studied, and variable or isolate dependent results were found. Subsequently, a screening experiment representing a wider range of bakery products was conducted using calcium propionate, potassium sorbate and sodium benzoate. The obtained data was modelled using survival analysis to determine 'spoilage-free time' for the fungi. At the low a(w) level (0.80) only Eurotium species grew within the test period of 30 days. Higher water activity levels as well as higher pH values decreased spoilage-free times of the fungi. The preservative calcium propionate was less effective than potassium sorbate and sodium benzoate.

Acids↗

Study of benzoate, propionate, and sorbate salts as mould spoilage inhibitors on intermediate moisture bakery products of low pH (4.5-5.5).

A hurdle technology approach has been applied to control common mold species causing spoilage of intermediate moisture bakery products (Eurotium spp., Aspergillus spp., and Penicillium corylophilum), growing on a fermented bakery product analogue (FBPA). The factors studied included a combination of different levels of weak acid preservatives (potassium sorbate, calcium propionate, and sodium benzoate; 0-0.3%), pH (4.5-5.5), and water activity (a(w); 0.80-0.90). Potassium sorbate was found to be the most effective in preventing fungal spoilage of this kind of products at the maximum concentration tested (0.3%) regardless of a(w). The same concentration of calcium propionate and sodium benzoate was effective only at low a(w) levels. On the other hand, potassium sorbate activity was slightly reduced at pH 5.5, the 0.3% being only effective at 0.80 a(w). These findings indicate that potassium sorbate may be a suitable preserving agent to inhibit deterioration of a FBPA of slightly acidic pH (near 4.5) by xerophilic fungi. Further studies have to be done in order to adjust the minimal inhibitory concentration necessary to obtain a product with the required shelf life.

Acids↗

Use of a MS-electronic nose for prediction of early fungal spoilage of bakery products.

A MS-based electronic nose was used to detect fungal spoilage (measured as ergosterol concentration) in samples of bakery products. Bakery products were inoculated with different Eurotium, Aspergillus and Penicillium species, incubated in sealed vials and their headspace sampled after 2, 4 and 7 days. Once the headspace was sampled, ergosterol content was determined in each sample. Different electronic nose signals were recorded depending on incubation time. Both the e-nose signals and ergosterol levels were used to build models for prediction of ergosterol content using e-nose measurements. Accuracy on prediction of those models was between 87 and 96%, except for samples inoculated with Penicillium corylophilum where the best predictions only reached 46%.

Aspergillus↗

Risk assessment of the use of sub-optimal levels of weak-acid preservatives in the control of mould growth on bakery products.

The hurdle technology approach was used to prevent fungal growth of common contaminants of bakery products including isolates belonging to the genera Eurotium, Aspergillus and Penicillium. Several levels (0.003%, 0.03% and 0.3%) of calcium propionate, potassium sorbate and sodium benzoate were assayed on a model agar system in a full-factorial experimental design in which the other factors assayed were pH (4.5, 6 and 7.5) and a(w) (0.80, 085, 0.90 and 0.95). Potassium sorbate was found to be the more suitable preservative to be used in combination with the common levels of pH and a(w) in Spanish bakery products. Sub-optimal concentrations (0.003% and sometimes 0.03%) led to an enhancement of fungal growth. None of the preservatives had a significant inhibitory effect at neutral pH.

Antifungal Agents↗

Efficacy of sorbates on the control of the growth of Eurotium species in bakery products with near neutral pH.

The effects of sorbic acid and potassium sorbate on growth of different Eurotium isolates when added to a bakery product analogue were tested under different environmental conditions. Water activity of the products was adjusted to values in the range of 0.75-0.90, and storage temperatures were in the range of 15-30 degrees C. Preservatives were added in concentrations ranging from 0.025% to 0.2%. It was observed that 0.025% and 0.05% concentrations always enhanced the isolates growth, while 0.1% had little preservative effect. Finally, even the highest concentration (0.2%) was not suitable as it only controlled fungal growth under certain water activity and temperature levels. It was concluded that these weak-acid preservatives are not useful when added to bakery products with near to neutral pH.

Bread↗

Consecutive salmonella outbreaks traced to the same bakery.

Two consecutive community outbreaks of Salmonella enteritidis phage type 4 (PT4) traced to the same bakery occurred in Cardiff, Wales during August-September 1992. In the first outbreak, illness was associated with eating custard slices (odds ratio 23.8, 95% confidence interval 6.5-94.4, P < 0.0001), and in the second, with eating fresh cream cakes (odds ratio 15.8, 95% confidence interval 1.6-374, P = 0.004). Environmental investigations implicated cross-contamination during preparation of the cold-custard mix as the cause of the first outbreak, and inadequate cleaning and disinfection of nozzles used for piping cream in the second outbreak. S. enteritidis PT4 was isolated from fresh cream sponge cake retained by a case and from two fresh cream cakes and four environmental swabs obtained at the bakery. This incident illustrates the hazard of widespread environmental contamination with salmonella and the need for thorough environmental cleansing for any premises implicated in an outbreak of food poisoning.

Adolescent↗

Cryptic species related to Daldinia concentrica and D. eschscholzii, with notes on D. bakeri.

Daldinia macaronesica (from the Canary Islands and Madeira), D. palmensis (from the Canary Islands), D. martinii and D. raimundi (from Sicily), and D. vanderguchtiae (from Jersey, Channel Islands) spp. nov., are described, based on new combinations of teleomorphic and anamorphic characters. They all resemble the pantropical D. eschscholzii and/or the European D. concentrica with regard to teleomorphic characters and secondary metabolite profiles generated by analytical HPLC. The status of the newly described taxa was established by SEM of ascospores and microscopic studies of their anamorphs in comparison with various materials of the aforementioned known species. HPLC and SEM studies on the holotype of D. bakeri confirmed its relationships to D. fissa and D. loculata. Yellowish pigments contained in the type specimen of D. bakeri are probably artificial.

Chromatography, High Pressure Liquid↗

Antifungal activity of volatile compounds generated by essential oils against fungi commonly causing deterioration of bakery products.

AIMS: To investigate the volatile fractions of 16 essential oils for activity against the more common fungi causing spoilage of bakery products, Eurotium amstelodami, E. herbariorum, E. repens, E. rubrum, Aspergillus flavus, A. niger and Penicillium corylophilum. METHODS AND RESULTS: The study applied 50 microl of pure essential oils in a sterilized filter paper, were carried out at pH 6 and at different water activity levels (0.80-0.90). First, a wheat flour based agar medium was used, where cinnamon leaf, clove, bay, lemongrass and thyme essential oils where found to totally inhibit all microorganisms tested. These five essential oils were then tested in sponge cake analogues, but the antifungal activity detected was much more limited. CONCLUSION: Five essential oils showed potential antifungal capacity against all species tested, over a wide range of water availability. Their activity, however, seems to be substrate-dependent. More research is needed to make them work in real bakery products, as in the preliminary study limited effectiveness was found. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential of the cinnamon leaf, clove, bay, lemongrass and thyme essential oils against species belonging to Eurotium, Aspergillus and Penicillium genus has been demonstrated.

Agar↗

Occupational rhinitis: diagnostic criteria, relation to lower airway symptoms and IgE sensitization in bakery workers.

CONCLUSIONS: The use of different diagnostic criteria has considerable consequences for the prevalence estimates of occupational rhinitis. There is a strong relationship between occupational rhinitis and lower airway symptoms. Storage mites appear to be important occupational allergens in Norwegian bakeries. OBJECTIVES: To study the consequences of various diagnostic criteria on the prevalence of occupational rhinitis, assess the prevalence of IgE sensitization and explore the relationships between upper and lower airway symptoms and between symptoms and IgE sensitization. MATERIAL AND METHODS: A total of 197 employees in 6 bakeries were interviewed and completed a questionnaire. A skin prick test was performed, total and specific IgE were determined and a histamine release test was performed for relevant allergens. The criteria for the diagnosis of occupational rhinitis were based on the 1994 International Consensus Report on Rhinitis. RESULTS: The prevalence of occupational rhinitis varied between 23% and 50%, depending on the criteria used. The occurrence of nasal symptoms was found to precede the development of lower airway symptoms. Occupational rhinitis, both IgE- and non-IgE-mediated, was associated with asthma symptoms. The most frequent causes of sensitization (20%) were different species of storage mites. Storage mite sensitization was related to occupational rhinitis and work exposure.

Acaridae↗

Bioavailability of elemental iron powders to rats is less than bakery-grade ferrous sulfate and predicted by iron solubility and particle surface area.

Foods are fortified with elemental forms of iron to reduce iron deficiency. However, the nutritional efficacy of current, commercially produced elemental iron powders has not been verified. We determined the bioavailability of six commercial elemental iron powders and examined how physicochemistry influences bioavailability. Relative biological value (RBV) of the iron powders was determined using a hemoglobin repletion/slope ratio method, treating iron-deficient rats with repletion diets fortified with graded quantities of iron powders, bakery-grade ferrous sulfate or no added iron. Iron powders were assessed physicochemically by measuring iron solubility in hydrochloric acid at pH 1.0 and 1.7, surface area by nitrogen gas adsorption and surface microstructure by electron microscopy. Bioavailability from the iron powders, based on absolute iron intake, was significantly less than from FeSO4 (100%; P < 0.05) with the following rank order: Carbonyl (64%; Ferronyl, U.S.) > Electrolytic (54%; A-131, U.S.) > Electrolytic (46%; Electrolytic Iron, India) > H-Reduced (42%; AC-325, U.S.) > Reduced (24%; ATOMET 95SP, Canada) > CO-Reduced (21%; RSI-325, Sweden). Solubility testing of the iron powders resulted in different relative rankings and better RBV predictability with increasing time at pH 1.7 (R2 = 0.65 at 150 min). The prediction was improved with less time and lower pH (R2 = 0.82, pH 1.0 at 30 min). Surface area, ranging from 90 to 370 m2/kg, was also highly predictive of RBV (R2 = 0.80). Bioavailability of iron powders is less than bakery-grade ferrous sulfate and varies up to three times among different commercial forms. Solubility at pH 1.0 and surface area were predictive of iron bioavailability in rats.

Animals↗

Small bakeries--a cross-sectional study of respiratory symptoms, sensitization and dust exposure.

This cross-sectional study investigated the prevalence of respiratory symptoms and sensitization to dust components in 224 individuals in 18 small bakeries in Scotland. Each work practice in the bakeries was characterized by an assessment of dust exposure and assigned to a category with either a direct exposure to flour dust of an indirect exposure to flour dust. We found that work-related respiratory symptoms were significantly associated with specific IgE to wheat flour and amylase but not to exposure category (except for nasal/eye symptoms). However, specific IgE to wheat flour was significantly associated with exposure category. There was a higher prevalence of immunological sensitization, reporting of work-related respiratory symptoms and exposure to dust than in other studies and of the 144 personal dust sample results taken, 21 (14.6%) of the total exceeded 10 mg/m3, the substantial dust concentration as outlined by the COSHH Regulations. Follow-up of those with work-related asthma symptoms (questionnaire response) was inconclusive of the work-relatedness of their symptoms, although it did confirm respiratory morbidity.

Adult↗

Latent period for symptomatic sensitization in bakeries.

AIM: To describe the latent period for symptomatic sensitization in bread bakery workers. METHODS: Data on the latent period for symptomatic sensitization, resulting in either asthma or rhinitis, were obtained from an in-house health surveillance programme in a single large organization. RESULTS: Over a period of 10 years, 90 employees were identified with symptoms attributable to sensitization. The mean latent period was 7.3 years, with three employees describing the onset of symptoms in their first year of exposure. CONCLUSIONS: The long latent period, typically more than 1 year, suggests that health surveillance on appointment and then at annual intervals thereafter should be adequate to identify affected individuals in a bakery environment.

Asthma↗