In vitro β‐Carotene Bioaccessibility and Lipid Digestion in Emulsions: Influence of Pectin Type and Degree of Methyl‐Esterification

Citrus pectin (CP) and sugar beet pectin (SBP) were demethoxylated and fully characterized in terms of pectin properties in order to investigate the influence of the pectin degree of methyl‐esterification (DM) and the pectin type on the in vitro β‐carotene bioaccessibility and lipid digestion in emulsions. For the CP based emulsions containing β‐carotene enriched oil, water and pectin, the β‐carotene bioaccessibility, and lipid digestion were higher in the emulsions with pectin with a higher DM (57%; “CP57 emulsion”) compared to the emulsions with pectin with a lower DM (30%; “CP30 emulsion”) showing that the DM plays an important role. In contrast, in SBP‐based emulsions, nor β‐carotene bioaccessibility nor lipid digestion were dependent on pectin DM. Probably here, other pectin properties are more important factors. It was observed that β‐carotene bioaccessibility and lipid digestion were lower in the CP30 emulsion in comparison with the CP57, SBP32, and SBP58 emulsions. However, the β‐carotene bioaccessibility of CP57 emulsion was similar to that of the SBP emulsions, whereas the lipid digestion was not. It seems that pectin type and pectin DM (in case of CP) are determining which components can be incorporated into micelles. Because carotenoids and lipids have different structures and polarities, their incorporation may be different. This knowledge can be used to engineer targeted (digestive) functionalities in food products. If both high β‐carotene bioaccessibility and high lipid digestion are targeted, SBP emulsions are the best options. The CP57 emulsion can be chosen if high β‐carotene bioaccessibility but lower lipid digestion is desired.     

Microencapsulated Lactobacillus rhamnosus GG powders: relationship of powder physical properties to probiotic survival during storage

Freeze-dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion-based formulation stabilized by whey protein and resistant starch and either spray-dried or freeze-dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined. Particle size analysis and scanning electron microscopy showed that spray-dried LGG microcapsules (SDMC) were small spherical particles, whereas freeze-dried LGG microcapsules (FDMC) were larger nonspherical particles. Moisture sorption isotherms obtained using dynamic vapor sorption showed a slightly higher water uptake in spray-dried microcapsules. The effect of water mobility, as measured by nuclear magnetic resonance (NMR) spectroscopy, at various water activities (a(w) 0.32, 0.57, and 0.70) and probiotic viability during storage at 25 °C was also examined. Increasing the relative humidity of the environment at which the samples were stored caused an increase in water mobility and the rate of loss in viability. The viability data during storage indicated that SDMC had better storage stability compared to FDMC. Although more water was adsorbed for spray-dried than freeze-dried microcapsules, water mobility was similar for corresponding storage conditions because there was a stronger water-binding energy for spray-dried microcapsule. This possibly accounted for the improved survival of probiotics in spray-dried microcapsules.     

Application of Kluyveromyces marxianus, Lactobacillus delbrueckii ssp. bulgaricus and L. helveticus for sourdough bread making

The application of Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) as starter cultures for sourdough bread making was examined. Production of lactic and acetic acids, bread rising, volatile composition, shelf-life and organoleptic quality of the sourdough breads were evaluated. The amount of starter culture added to the flour, the dough fermentation temperature and the amount of sourdough used were examined in order to optimise the bread making process. The use of mixed cultures led to higher total titratable acidities and lactic acid concentrations compared to traditionally made breads. Highest acidity (3.41 g lactic acid/kg of bread) and highest resistance to mould spoilage were observed when bread was made using 50% sourdough containing 1% K. marxianus and 4% L. delbrueckii ssp. bulgaricus. The use of these cultures also improved the aroma of sourdough breads, as shown by sensory evaluations and as revealed by GC–MS analysis.     

“Probability transforms” of digital pictures

Let g be any local property (e.g., gray level or gradient magnitude) defined on a digital picture. Let p_g(z) be the relative frequency with which g has value z. At each point (x,y) of the picture we can display p_g[g(x,y)], appropriately scaled; the result is called the p_g transform of the picture. Alternatively, we can use joint or conditional frequencies of pairs of local properties to define transforms. This note gives examples of such transforms for various gs and discusses their possible uses and limitations.     

Responses of Dairy Cows to Exogenous Bovine Growth Hormone Administered During Early Lactation

Bovine growth hormone was administered to eight Holstein cows during two 10-d periods (commencing 20 and 60 d postpartum). Treatments involved daily subcutaneous injection of excipient (control) or of 50 IU growth hormone. Feed intake and yields of milk and milk components were measured during the last 5 d of treatment. In the first injection period, milk yield of treated cows was 6% greater than that of controls (36.2 kg/d). Fat content of milk was increased by treatment with the result that fat yield was elevated by 25%. Protein content was not altered. In the second period, milk yield increased by 12%, but composition of milk was not changed. As a result, milk energy secretion was increased by a similar amount in each treatment period (4.4 versus 4.5 Mcal/d). Feed intake was not changed in either period. During early lactation the ability of cows to increase milk yield in response to exogenous growth hormone may be limited by the supply of glucose for lactose synthesis rather than by ability to mobilize body reserves in support of lactation.     

Enhancement of contrast in living and fixed specimens by the use of fibre optics

A method is described which enhances the contrast of living and fixed specimens examined with the stereomicroscope. It consists of immersing the ends of flexible fibre optic light sources together with the specimen in the fluid used for examination. It is reported that not only does this method increase the contrast of living specimens but that it may also be applied to specimens being prepared as thin sections or freeze fracture surfaces for examination with the transmission electron microscope. A further method of enhancement of contrast is suggested which involves the fitting of light filters of complementary colours, one to each of the fibre optic light sources, before immersion with the specimen.     

Antioxidant Capacity of Fruit Extracts of Blackberry (Rubus sp.) Produced in Different Climatic Regions

A range of blackberry genotypes harvested in different seasons and regions in Mexico (Michoacan) and in the United States (Pacific Northwest) were collected to determine their antioxidant capacity using oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays. Total acidity, ascorbic acid, soluble solids, total phenols, and total anthocyanins, as well as the correlation between all these parameters, were determined for all treatments. Total acidity ranged from 4.22% in wild blackberry from Patzcuaro, Mexico, to 1.02% in ‘Evergreen’ from Woodburn, Oreg. These treatments were also the outliers in terms of ascorbic acid content. Cultivar ‘Brazos’ did not exhibit any significant differences in acidity or ascorbic acid as a consequence of the geographic origin or harvest season. The highest concentration of soluble solids was recorded for ‘Evergreen’ from Woodburn and relatively low soluble solids levels were recorded for all the Mexican treatments. Wild blackberry from Patzcuaro exhibited the highest values for ORAC, FRAP, total phenolic and anthocyanin content. Other relatively high antioxidant capacity values were detected for ‘Marion’ and ‘Evergreen’, both produced in Oregon. Different cultivars grown in the same region/season consistently showed differences in antioxidant capacity. There was little effect of harvest season on phenolic levels. We conclude that levels of total acidity, ascorbic acid, soluble solids, antioxidant capacity, and polyphenols mainly depended on the genotype and not on the climate or the season. ORAC and FRAP values were both highly correlated with each other, and with total phenols and anthocyanin content.     

Prevalence of Salmonella enterica, Listeria monocytogenes, and Escherichia coli virulence factors in bulk tank milk and in-line filters from U.S. dairies

The zoonotic bacteria Salmonella enterica, Listeria monocytogenes, and Escherichia coli are known to infect dairy cows while not always causing clinical signs of disease. These pathogens are sometimes found in raw milk, and human disease outbreaks due to these organisms have been associated with the consumption of raw milk or raw milk products. Bulk tank milk (BTM) samples (536) and in-line milk filters (519) collected from dairy farms across the United States during the National Animal Health Monitoring System's Dairy 2007 study were analyzed by real-time PCR for the presence of S. enterica and pathogenic forms of E. coli and by culture techniques for the presence of L. monocytogenes. S. enterica was detected in samples from 28.1% of the dairy operations, primarily in milk filters. Salmonella was isolated from 36 of 75 PCR-positive BTM samples and 105 of 174 PCR-positive filter samples, and the isolates were serotyped. Cerro, Kentucky, Muenster, Anatum, and Newport were the most common serotypes. L. monocytogenes was isolated from 7.1% of the dairy operations, and the 1/2a complex was the most common serotype, followed by 1/2b and 4b (lineage 1). Shiga toxin genes were detected in enrichments from 15.2% of the BTM samples and from 51.0% of the filters by real-time PCR. In most cases, the cycle threshold values for the PCR indicated that toxigenic strains were not a major part of the enrichment populations. These data confirm those from earlier studies showing significant contamination of BTM by zoonotic bacterial pathogens and that the consumption of raw milk and raw milk products presents a health risk.     

Microstructure and nutrient composition of hairless canary seed and its potential as a blending flour for food use

Canary seed is a true cereal with unique composition. The current study employed light and fluorescence microscopy to visualise starch, protein, phenolics and phytate in hairless canary seed (CDC Maria), a cultivar developed potentially for food use. Macronutrients, minerals and vitamins were evaluated in the developed cultivar and compared with a commercial hairy canary seed, cv. Keet. A control common wheat, cv. Katepwa, was grown adjacent to the canary seed varieties. The compositions of the two canary seed varieties were found to be similar with an average of 55.8 g/100 g of starch, 23.7% g/100 g of protein, 7.9% of crude fat, 7.3 g/100 g of total dietary fibre, 1.8 g/100 g of soluble sugar and 2.3 g/100 g of total ash in the whole grain. Regardless of the milling fraction (whole grain flour, white flour or bran), canary seed had more protein and crude fat and less starch, total dietary fibre and soluble sugar than had wheat. It also had higher concentrations of several minerals and vitamins than did wheat. The structure of the canary seed grain exhibited compound starch granules and protein bodies embedded in a protein matrix similar to that of the oat kernel. Baking tests showed that bread made with 100% hairless canary seed flour was significantly lower in loaf volume and crust and crumb colour than was wheat bread. However, bread with loaf volume, specific volume and crust colour comparable to those of the bread control was achieved by using up to 25% of hairless canary seed or 15% of roasted canary seed flour, thus demonstrating its potential for food applications.     

Introduction of sulfhydryl groups and disulfide linkage to mungbean 8Sα globulin and effects on physicochemical and functional properties

Sulfhydryl groups and disulfide bond were introduced in mungbean's major storage protein, 8Sα globulin, by protein engineering to improve structural stability and functional properties. Five modified proteins or mutants (F59C, I99C, A213C, one free sulfhydryl group; I99C/A213, one disulfide bridge; F59C/I99C/A213C, one free sulfhydryl group and one disulfide linkage) were expressed in Escherichia coli at a yield similar to that of the unmodified protein or wild type (WT) in soluble form (38%). The number of introduced groups in the mutants was confirmed by Ellman analysis. Mutant and WT proteins exhibited similar elution patterns on gel filtration indicating their trimeric native conformation. Mutants had 2 to 3.8 °C higher T_m values than WT and were digested by chymotrypsin at 52–58% in 60 min but exhibited different digestion patterns. All mutants showed greater hardness of heat-induced gels than WT, especially I99C/A213C and F59C/I99C/A213C. Results indicate the improved structural stability of the modified 8Sα globulin.