Quality Attributes of Ultra-High Temperature-Treated Model Beverages Prepared with Faba Bean Protein Concentrates.

The objective of this research was to develop a model faba bean drink with a high concentration of protein (>4% w/w). The protein molecular weights and frequency for both faba and soy were assessed using SDS-PAGE. Results showed similarities in the protein molecular weight of both faba and soy (mainly 11S globulin ~Glycinin and 7S globulin ~ß-conglycinin). Thus, faba can be considered as a potential soy replica in plant-based milk beverages. Oil-in-water emulsions (5-8% w/w available protein) were prepared using faba bean protein concentrate (FPC), 1% sunflower oil, and 0.2% sunflower lecithin. These emulsions were used as model beverages and were further investigated for UHT processibility, stability, and physicochemical properties. The physicochemical properties of emulsions at various processing stages viz., coarse emulsification, homogenisation, and UHT, were measured. An increase in the protein concentration and thermal treatment resulted in an increased oil droplet size, coalescence and flocculation, and protein aggregation. Lower protein concentrations viz., 5-6%, showed greater negative ζ-potential, and thereby, high dispersibility through enhanced electrostatic repulsions than those of higher concentrations (7-8%). Furthermore, an increase in protein concentration and UHT treatment resulted in an increased creaming index. In total, 21 different volatile compounds were detected and quantified, representing different chemical classes, namely alcohols, aldehydes, ketones, esters, furan, and acids. These volatiles have major consequences for the overall flavour chemistry of the model beverage product. Overall, this study showed the potential for application of faba bean as a protein source in UHT-treated legume-based beverages and identified areas for further development.

The Assessment of Brain Functional Changes in the Temporal Lobe Epilepsy Patient with Cognitive Impairment by Resting-state Functional Magnetic Resonance Imaging.

OBJECTIVES: The objective of the study was to detect functional changes in the brain of cognitive impairment-temporal lobe epilepsy (CI-TLE) patient and to sort out the possible mechanism involved in CI in CI-TLE patients using resting-state functional magnetic resonance imaging (RS-fMRI). MATERIAL AND METHODS: Fifty-eight TLE cases were included, which was divided into 44 TLE patients without CI (cognitive not impairment [CNI]-TLE) and 14 TLE patients with CI (CI-TLE). The normal control (NC) group consisted of 40 participants. RS-fMRI data preprocessing was carried out in statistical parametric mapping (SPM) software. The data were realigned, coregistered, normalized, and finally smoothened and then were taken for amplitude of low-frequency fluctuation (ALFF) calculation in RS-fMRI data analysis toolkit (REST) software. For data analysis, voxel-wise two-sample t-test was carried out between TLE group and NC group; CI-TLE group and cognitive not impairment-TLE (CNI-TLE) group in SPM software, a cluster >10 voxels and P < 0.01 was considered to be significant. RESULTS: Compared to NC, the TLE patients showed increased ALFF activation mostly in parahippocampal gyrus (PG), frontal lobe, midbrain, pons, insula, inferior temporal gyrus, and anterior cingulate gyrus (ACG) while decreased ALFF value was seen in posterior cingulate gyrus, cuneus, cerebellum posterior lobe, inferior parietal lobule (IPL), and superior temporal gyrus. Compared to CNI-TLE, CI-TLE patients showed increased ALFF in middle temporal gyrus (MTG), cuneus, ACG, IPL, middle frontal gyrus (MFG), superior frontal gyrus (SFG), cerebellum posterior lobe, and decreased ALFF cluster in the corpus callosum and MFG. CONCLUSION: Between TLE and NC, we found increased ALFF activation in PG, frontal lobe, thalamus, insula, midbrain, and pons in TLE patient. Between CI and CNI TLE, area of executive control network and default model network, especially in MTG, ACG, IPL, MFG, and SFG, had increased ALFF value in CI-TLE patient. Activation of these areas should be because of the decompensation mechanism.

Engineering Trienoic Fatty Acids into Cottonseed Oil Improves Low-Temperature Seed Germination, Plant Photosynthesis and Cotton Fiber Quality.

Alpha-linolenic acid (ALA, 18:3Δ9,12,15) and γ-linolenic acid \ (GLA, 18:3Δ6,9,12) are important trienoic fatty acids, which are beneficial for human health in their own right, or as precursors for the biosynthesis of long-chain polyunsaturated fatty acids. ALA and GLA in seed oil are synthesized from linoleic acid (LA, 18:2Δ9,12) by the microsomal ω-3 fatty acid desaturase (FAD3) and Δ6 desaturase (D6D), respectively. Cotton (Gossypium hirsutum L.) seed oil composition was modified by transforming with an FAD3 gene from Brassica napus and a D6D gene from Echium plantagineum, resulting in approximately 30% ALA and 20% GLA, respectively. The total oil content in transgenic seeds remained unaltered relative to parental seeds. Despite the use of a seed-specific promoter for transgene expression, low levels of GLA and increased levels of ALA were found in non-seed cotton tissues. At low temperature, the germinating cottonseeds containing the linolenic acid isomers elongated faster than the untransformed controls. ALA-producing lines also showed higher photosynthetic rates at cooler temperature and better fiber quality compared to both untransformed controls and GLA-producing lines. The oxidative stability of the novel cottonseed oils was assessed, providing guidance for potential food, pharmaceutical and industrial applications of these oils.

The Diagnostic Ability of rs-DWI to Detect Subtle Acute Infarction Lesion in the Different Regions of the Brain and the Comparison between Different b-Values.

OBJECTIVE: To evaluate the diagnostic ability of rs-DWI to detect subtle acute infarction lesion in the different regions of the brain in comparison to routine DWI and the comparison between different b-values. METHOD: 35 acute brain infarction patients were included. The subtle acute infarction lesions in ss-DWI and rs-DWI sequence were evaluated in 9 anatomical regions of the brain, and the ss-EPI DWI was also acquired with different b-values of 0, 1000, 2000, and 3000s/mm2. The McNemar test was performed for comparing the diagnostic ability of ss-DWI and rs-DWI and different b-values. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the whole brain and in each anatomical region were calculated. RESULT: A total of 406 subtle acute infarction lesions were confirmed. The ss-DWI detected 338 subtle lesions, out of which 318 were true positive and 20 were false positive lesions. The rs-DWI detected 386 subtle lesions, out of which 385 were true positive lesions and 1 was true negative lesion. Sensitivity, specificity, positive predictive value, and negative predictive value in rs-DWI were better than ss-DWI in all anatomical regions of the brain. In the comparison of different b-values, b2000 was found better among b1000, b2000, and b3000. CONCLUSION: The rs-DWI offers a useful alternative to routine DWI for detecting the subtle acute infarctions, especially in the regions that are susceptible to distortion as in frontal cortex. In addition, high b-value can also provide benefit by increasing diffusion weighting but further raising can deteriorate image quality as SNR is decreased.

Genomic and metabolic characterization of spoilage-associated Pseudomonas species.

Pseudomonas are common spoilage agents of aerobically stored fresh foods. Their ability to cause spoilage is species- and may be strain-specific. To improve our understanding of the meat and milk spoilage agents Pseudomonas fragi and Pseudomonas lundensis, we sequenced the genomes of 12 P. fragi and seven P. lundensis isolates. These genomes provided a dataset for genomic analyses. Key volatile organic compounds (VOCs) produced or metabolised by the isolates were determined during their growth on a beef paste and where possible, metabolic activity was associated with gene repertoire. Genome analyses showed that the isolates included in this work may belong to more than two Pseudomonas species with possible spoilage potential. Pan-genome analyses demonstrated a high degree of diversity among the P. fragi and genetic flexibility and diversity may be traits of both species. Growth of the P. lundensis isolates was characterised by the production of large amounts of 1-undecene, 5-methyl-2-hexanone and methyl-2-butenoic acid. P. fragi isolates produced extensive amounts of methyl and ethyl acetate and the production of methyl esters predominated over ethyl esters. Some of the P. fragi produced extremely low levels of VOCs, highlighting the importance of strain-specific studies in food matrices. Furthermore, although usually not considered to be denitrifiers, all isolates generated molecular nitrogen, indicating that at least some steps of this pathway are intact.

Effect of ultrasound-enhanced fat separation on whey powder phospholipid composition and stability.

Fat from freshly pasteurized liquid whey was partially separated by gravity for 5, 10, and 30min, with and without simultaneous application of ultrasound. Ultrasound treatments were carried out at 400 and 1,000 kHz at different specific energy inputs (23-390 kJ/kg). The fat-enriched top layers (L1) and the fat-depleted bottom layers (L2) were separately removed and freeze-dried. Nonsonicated and sonicated L2 powders were stored for 14d at ambient temperature to assess their oxidative stability. Creaming was enhanced at both frequencies and fat separation increased with higher ultrasonic energy, extended sonication, or both. The oxidative volatile compound content decreased in defatted whey powders below published odor detection threshold values for all cases. Sonication had a minor influence on the partitioning of phospholipids with fat separation. The current study suggested that ultrasonication at high frequency enhanced fat separation from freshly pasteurized whey while improving whey powder oxidative stability.

Cavitation and non-cavitation regime for large-scale ultrasonic standing wave particle separation systems--In situ gentle cavitation threshold determination and free radical related oxidation.

We here suggest a novel and straightforward approach for liter-scale ultrasound particle manipulation standing wave systems to guide system design in terms of frequency and acoustic power for operating in either cavitation or non-cavitation regimes for ultrasound standing wave systems, using the sonochemiluminescent chemical luminol. We show that this method offers a simple way of in situ determination of the cavitation threshold for selected separation vessel geometry. Since the pressure field is system specific the cavitation threshold is system specific (for the threshold parameter range). In this study we discuss cavitation effects and also measure one implication of cavitation for the application of milk fat separation, the degree of milk fat lipid oxidation by headspace volatile measurements. For the evaluated vessel, 2 MHz as opposed to 1 MHz operation enabled operation in non-cavitation or low cavitation conditions as measured by the luminol intensity threshold method. In all cases the lipid oxidation derived volatiles were below the human sensory detection level. Ultrasound treatment did not significantly influence the oxidative changes in milk for either 1 MHz (dose of 46 kJ/L and 464 kJ/L) or 2 MHz (dose of 37 kJ/L and 373 kJ/L) operation.

Chronic administration of a microencapsulated probiotic enhances the bioavailability of orange juice flavanones in humans.

Orange juice (OJ) flavanones are bioactive polyphenols that are absorbed principally in the large intestine. Ingestion of probiotics has been associated with favorable changes in the colonic microflora. The present study examined the acute and chronic effects of orally administered Bifidobacterium longum R0175 on the colonic microflora and bioavailability of OJ flavanones in healthy volunteers. In an acute study volunteers drank OJ with and without the microencapsulated probiotic, whereas the chronic effects were examined when OJ was consumed after daily supplementation with the probiotic over 4 weeks. Bioavailability, assessed by 0-24h urinary excretion, was similar when OJ was consumed with and without acute probiotic intake. Hesperetin-O-glucuronides, naringenin-O-glucuronides, and hesperetin-3'-O-sulfate were the main urinary flavanone metabolites. The overall urinary excretion of these metabolites after OJ ingestion and acute probiotic intake corresponded to 22% of intake, whereas excretion of key colon-derived phenolic and aromatic acids was equivalent to 21% of the ingested OJ (poly)phenols. Acute OJ consumption after chronic probiotic intake over 4 weeks resulted in the excretion of 27% of flavanone intake, and excretion of selected phenolic acids also increased significantly to 43% of (poly)phenol intake, corresponding to an overall bioavailability of 70%. Neither the probiotic bacterial profiles of stools nor the stool moisture, weight, pH, or levels of short-chain fatty acids and phenols differed significantly between treatments. These findings highlight the positive effect of chronic, but not acute, intake of microencapsulated B. longum R0175 on the bioavailability of OJ flavanones.

Influence of heat and shear induced protein aggregation on the in vitro digestion rate of whey proteins.

Protein intake is essential for growth and repair of body cells, the normal functioning of muscles, and health related immune functions. Most food proteins are consumed after undergoing various degrees of processing. Changes in protein structure and assembly as a result of processing impact the digestibility of proteins. Research in understanding to what extent the protein structure impacts the rate of proteolysis under human physiological conditions has gained considerable interest. In this work, four whey protein gels were prepared using heat processing at two different pH values, 6.8 and 4.6, with and without applied shear. The gels showed different protein network microstructures due to heat induced unfolding (at pH 6.8) or lack of unfolding, thus resulting in fine stranded protein networks. When shear was applied during heating, particulate protein networks were formed. The differences in the gel microstructures resulted in considerable differences in their rheological properties. An in vitro gastric and intestinal model was used to investigate the resulting effects of these different gel structures on whey protein digestion. In addition, the rate of digestion was monitored by taking samples at various time points throughout the in vitro digestion process. The peptides in the digesta were profiled using SDS-polyacrylamide gel electrophoresis, reversed-phase-HPLC and LC-MS. Under simulated gastric conditions, whey proteins in structured gels were hydrolysed faster than native proteins in solution. The rate of peptides released during in vitro digestion differed depending on the structure of the gels and extent of protein aggregation. The outcomes of this work highlighted that changes in the network structure of the protein can influence the rate and pattern of its proteolysis under gastrointestinal conditions. Such knowledge could assist the food industry in designing novel food formulations to control the digestion kinetics and the release of biologically active peptides for desired health outcome.

Sequential low and medium frequency ultrasound assists biodegradation of wheat chaff by white rot fungal enzymes.

The consequences of ultrasonic pre-treatment using low (40 kHz) and medium (270 kHz) frequency (40 kHz followed by 270 kHz) on the degradation of wheat chaff (8 g 100ml(-1) acetate buffer, pH 5) were evaluated. In addition, the effects of the ultrasonic pre-treatment on the degradation of the wheat chaff when subsequently exposed to enzyme extracts from two white rot fungi (Phanerochaete chrysosporium and Trametes sp.) were investigated. Pre-treatment by sequential low and medium frequency ultrasound had a disruptive effect on the lignocellulosic matrix. Analysis of the phenolic-derived volatiles after enzymatic hydrolysis showed that biodegradation with the enzyme extract obtained from P. chrysosporium was more pronounced compared to that of the Trametes sp. The efficacy of the ultrasonic pre-treatment was attributed to increased enzyme accessibility of the cellulose fibrils due to sonication-induced disruption of the plant surface structure, as shown by changes in the microstructure.

In vitro transport and satiety of a beta-lactoglobulin dipeptide and beta-casomorphin-7 and its metabolites.

Understanding the digestive behaviour and biological activities of dairy proteins may help to develop model dairy products with targeted health outcomes including increased satiety and healthy weight maintenance. Caseins and whey proteins constitute over 95% of milk proteins with consumption of these proteins associated with increased satiety and a decreased prevalence of metabolic disorders. To investigate the in vitro digestive behaviour and satiety of dairy proteins at the intestinal epithelium, the in vitro transport and hydrolysis of 500-2000 µM ß-casomorphin-7 (YPFPGPI or ß-CM7) and a ß-lactoglobulin (ß-Lg) dipeptide (YL) was measured using Caco-2 cell monolayers grown on transwells as a model of the intestinal epithelium. Transport of YL was concentration dependent and ranged from 0.37-5.26 × 10(-6) cm s(-1), whereas transport of ß-CM7 was only detected at 2000 µM and was significantly lower at 0.13 × 10(-6) cm s(-1). Rapid hydrolysis of ß-CM7 in the apical chamber by the Caco-2 cells produced three peptide metabolites: YP, GPI and FPGPI. All of these metabolites were detected in the basolateral chamber after 30 min with both the YP and GPI peptides transporting at a higher rate than intact ß-CM7. In vitro satiety was indicated by the secretion of cholecystokinin [26-33] (CCK-8) and glucagon-like peptide 1 (GLP-17-36NH2) in the STC-1 enteroendocrine cell model. CCK-8 secretion was highest in response to ß-CM7 followed by the ß-CM7 metabolite FPGPI. CCK-8 secretion however was not significantly stimulated by the tri- or dipeptides. Secretion of GLP-1 was not significantly stimulated by ß-CM7 or YL. These in vitro results suggest that dairy peptide size enhances CCK-8 secretion, whilst limiting transport across Caco-2 monolayers.

Production of particulates from transducer erosion: implications on food safety.

The formation of metallic particulates from erosion was investigated by running a series of transducers at various frequencies in water. Two low frequency transducer sonotrodes were run for 7.5h at 18kHz and 20kHz. Three high frequency plates operating at megasonic frequencies of 0.4MHz, 1MHz, and 2MHz were run over a 7days period. Electrical conductivity and pH of the solution were measured before and after each run. A portion of the non-sonicated and treated water was partially evaporated to achieve an 80-fold concentration of particles and then sieved through nano-filters of 0.1µm, 0.05µm, and 0.01µm. An aliquot of the evaporated liquid was also completely dried on strips of carbon tape to determine the presence of finer particles post sieving. An aliquot was analyzed for detection of 11 trace elements by Inductively Coupled Plasma Mass Spectroscopy (ICPMS). The filters and carbon tapes were analyzed by FE-SEM imaging to track the presence of metals by EDS (Energy Dispersive Spectroscopy) and measure the particle size and approximate composition of individual particles detected. Light microscopy visualization was used to calculate the area occupied by the particles present in each filter and high resolution photography was used for visualization of sonotrode surfaces. The roughness of all transducers before and after sonication was tested through profilometry. No evidence of formation of nano-particles was found at any tested frequency. High amounts of metallic micron-sized particles at 18kHz and 20kHz formed within a day, while after 7day runs only a few metallic micro particles were detected above 0.4MHz. Erosion was corroborated by an increase in roughness in the 20kHz tip after ultrasound. The elemental analysis showed that metal leach occurred but values remained below accepted drinking water limits, even after excessively long exposure to ultrasound. With the proviso that the particles measured here were only characterized in two dimensions and could be nanoparticulate in terms of the third dimension, this research suggests that there are no serious health implications resulting from the formation of nanoparticles under the evaluation conditions. Therefore, high frequency transducer plates can be safely operated in direct contact with foods. However, due to significant production of metallic micro-particulates, redesign of lower frequency sonotrodes and reaction chambers is advised to enable operation in various food processing direct-contact applications.

Synergism between ultrasonic pretreatment and white rot fungal enzymes on biodegradation of wheat chaff.

Lignocellulosic biomass samples (wheat chaff) were pretreated by ultrasound (US) (40kHz/0.5Wcm(-2)/10min and 400kHz/0.5Wcm(-2)/10min applied sequentially) prior to digestion by enzyme extracts obtained from fermentation of the biomass with white rot fungi (Phanerochaete chrysosporium or Trametes sp.). The accessibility of the cellulosic components in wheat chaff was increased, as demonstrated by the increased concentration of sugars produced by exposure to the ultrasound treatment prior to enzyme addition. Pretreatment with ultrasound increased the concentration of lignin degradation products (guaiacol and syringol) obtained from wheat chaff after enzyme addition. In vitro digestibility of wheat chaff was also enhanced by the ultrasonics pretreatment in combination with treatment with enzyme extracts. Degradation was enhanced with the use of a mixture of the enzyme extracts compared to that for a single enzyme extract.

Lipid oxidation volatiles absent in milk after selected ultrasound processing.

Ultrasonic processing can suit a number of potential applications in the dairy industry. However, the impact of ultrasound treatment on milk stability during storage has not been fully explored under wider ranges of frequencies, specific energies and temperature applications. The effect of ultrasonication on lipid oxidation was investigated in various types of milk. Four batches of raw milk (up to 2L) were sonicated at various frequencies (20, 400, 1000, 1600 and 2000kHz), using different temperatures (4, 20, 45 and 63°C), sonication times and ultrasound energy inputs up to 409kJ/kg. Pasteurized skim milk was also sonicated at low and high frequency for comparison. In selected experiments, non-sonicated and sonicated samples were stored at 4°C and were drawn periodically up to 14days for SPME-GCMS analysis. The cavitational yield, characterized in all systems in water, was highest between 400kHz and 1000kHz. Volatile compounds from milk lipid oxidation were detected and exceeded their odor threshold values at 400kHz and 1000kHz at specific energies greater than 271kJ/kg in raw milk. However, no oxidative volatile compounds were detected below 230kJ/kg in batch systems at the tested frequencies under refrigerated conditions. Skim milk showed a lower energy threshold for oxidative volatile formation. The same oxidative volatiles were detected after various passes of milk through a 0.3L flow cell enclosing a 20kHz horn and operating above 90kJ/kg. This study showed that lipid oxidation in milk can be controlled by decreasing the sonication time and the temperature in the system depending on the fat content in the sample among other factors.

Impact of ultrasound treatment on lipid oxidation of Cheddar cheese whey.

Ultrasound (US) has been suggested for many whey processing applications. This study examined the effects of ultrasound treatment on the oxidation of lipids in Cheddar cheese whey. Freshly pasteurized whey (0.86 L) was ultrasonicated in a contained environment at the same range of frequencies and energies for 10 and 30 min at 37°C. The US reactor used was characterized by measuring the generation of free radicals in deionized water at different frequencies (20-2000 kHz) and specific energies (8.0-390 kJ/kg). Polar lipid (PL), free and bound fatty acids and lipid oxidation derived compounds were identified and quantified before and after US processing using high performance liquid chromatography equipped with an evaporative light scattering detector (HPLC-ELSD), methylation followed by gas chromatography flame ionized detector (GC-FID) and solid phase micro-extraction gas chromatography mass spectrometry (SPME-GCMS), respectively. The highest concentration of hydroxyl radical formation in the sonicated whey was found between 400 and 1000 kHz. There were no changes in phospholipid composition after US processing at 20, 400, 1000 and 2000 kHz compared to non-sonicated samples. Lipid oxidation volatile compounds were detected in both non-sonicated and sonicated whey. Lipid oxidation was not promoted at any tested frequency or specific energy. Free fatty acid concentration was not affected by US treatment per se. Results revealed that US can be utilized in whey processing applications with no negative impact on whey lipid chemistry.

Regulation of milk protein solubility by a whey-derived proline-rich peptide product.

The effects of a bovine whey peptide product enriched in proline (wPRP) on the solubility of milk proteins were tested under ambient conditions or following heat treatment at 75 and 100 °C, for 1 and 15 min, followed by post-incubation storage at either ambient temperature or 4 °C for up to 7 d. wPRP promoted solubilisation of milk proteins in a concentration-dependent manner without heat treatment and also after heat treatment at 75 and 100 °C, and the effect was enhanced after storage under either ambient or refrigerated storage conditions. Interactions of wPRP and milk proteins were monitored by particle size analysis and tryptic digestion and specifically linked with solubilisation of αS1 casein (αS1-Cn), which supported observed changes in milk protein solubility. The results suggested that wPRP preferably prevented or reversed physical versus covalent protein aggregation, with the relaxation of hydrophobic interactions at 4 °C providing an additive effect. This application of wPRP represents a novel approach to stabilisation of dairy proteins following thermal processing with industrial usefulness yet to be explored.

Sheepmeat flavor and the effect of different feeding systems: a review.

Lamb has a unique flavor, distinct from other popular red meats. Although flavor underpins lamb's popularity, it can also be an impediment to consumer acceptance. Lack of familiarity with sheepmeat flavor itself can be a barrier for some consumers, and undesirable feed-induced flavors may also compromise acceptability. Against the backdrop of climate uncertainty and unpredictable rainfall patterns, sheep producers are turning to alternatives to traditional grazing pasture systems. Historically, pasture has been the predominant feed system for lamb production in Australia and around the world. It is for this reason that there has been a focus on "pastoral" flavor in sheep meat. Pasture-associated flavors may be accepted as "normal" by consumers accustomed to meat from pasture-fed sheep; however, these flavors may be unfamiliar to consumers of meat produced from grain-fed and other feed systems. Over the past few decades, studies examining the impacts of different feeds on lamb meat quality have yielded variable consumer responses ranging from "no effect" to "unacceptable", illustrating the diverse and sometimes inconsistent impacts of different forages on sheepmeat flavor. Despite considerable research, there is no consensus on which volatiles are essential for desirable lamb aroma and how they differ compared to other red meats, for example, beef. In contrast, comparatively little work has focused specifically on the nonvolatile taste components of lamb flavor. Diet also affects the amount of intramuscular fat and its fatty acid composition in the meat, which has a direct effect on meat juiciness and texture as well as flavor, and its release during eating. The effect of diet is far from simple and much still needs to be learned. An integrated approach that encompasses all input variables is required to better understand the impact of the feed and related systems on sheepmeat flavor. This review brings together recent research findings and proposes some novel approaches to gain insights into the relationship between animal diet, genetics, and sheepmeat quality.

Tocopherol and ascorbate have contrasting effects on the viability of microencapsulated Lactobacillus rhamnosus GG.

The antioxidants, sodium ascorbate and tocopherol, have contrasting effects on the viability of microencapsulated Lactobacillus rhamnosus GG (LGG) spray-dried powders during storage (4 and 25 °C; 32, 57, and 70% relative humidity). The addition of tocopherol improved probiotic viability during storage, while the incorporation of Na-ascorbate alone or in combination with tocopherol had detrimental effects on probiotic survival. The beneficial effect of tocopherol is a consequence of its chemical antioxidative action. The reduced viability in Na-ascorbate containing microcapsule formulations is hypothesized to be due primarily to the production of acetic acids arising from chemical degradation reactions and the catabolism of ascorbate by LGG. This study highlights the importance of considering the detrimental consequences of degradative chemical reactions and the metabolic fate of additives on the viability of probiotics when designing probiotic encapsulant formulations.

Production and sensory characterization of a bitter peptide from beta-casein.

Peptide beta-casein fragment 193-209 (beta-CN f193-209) was isolated and purified for detailed sensory analysis in different matrices. The purity of the peptide was >98%. The mass of the peptide was 1882.51 Da, which coincided with the expected mass of beta-CN f193-209. N-Terminal analysis confirmed that the peptide started at residue 193 on the published sequence of beta-casein. Detection thresholds were 0.03, 0.06, and 0.63% (w/w) for water, milk, and cheese, respectively. Descriptive sensory analysis confirmed that the peptide exhibited a bitter taste, which increased with increasing concentrations, with minimal other flavors or tastes detected. The beta-CN f193-209 can contribute to bitterness in cheeses.