Sonocrystallisation of Lactose in an Aqueous System

Although research on sonocrystallisation of lactose has been reported in the literature (yield and crystal size), the effect of ultrasound variables on nucleation and growth rate of lactose have not been studied. In this study, lactose crystallisation with ultrasound was compared with mechanical agitation using the induction time method at 22 °C. Ultrasound had a significant effect in reducing induction times and narrowing the metastable zone width but had no effect on individual crystal growth rate or morphology. A rapid decrease in induction time was observed up to 0.46 Wg-1 power density. Sonication up to 3 min decreased the induction time, but no further reduction was observed beyond 3 min. It was not possible to generate the nucleation rates achieved by sonication using agitation alone. 1 min sonication at 0.46 Wg1 power density followed by continuous stirring was found to be the optimum under the experimental conditions tested

Effect of guar gum on the physicochemical, thermal, rheological and textural properties of green edam cheese

In attempts to produce a low-fat cheese with a rheology and texture similar to that of a full-fat cheese, guar gum (within 0.0025–0.01%; w/v, final concentration) was added to low-fat milk. The obtained cheeses were characterised regarding their physicochemical, thermal, rheological and textural properties. Control cheeses were also produced with low and full-fat milk. The physicochemical properties of the guar gum modified cheeses were similar to those of the low-fat control. No significant differences were detected in the thermal properties (concerning the enthalpy and profile of water desorption) among all types of cheeses. The rheological behaviour of the 0.0025% modified cheese was very similar to the full-fat control. Overall, no trend was observed in the texture profile (hardness, cohesiveness, gumminess and elasticity) of the modified cheeses versus guar gum concentration, as well as in comparison with the control groups, suggesting that none of the studied polysaccharide concentrations simulated the textural functions of fat in Edam cheese

2-Deoxy-D-Glucose Treatment Induces Ketogenesis, Sustains Mitochondrial Function, and Reduces Pathology in Female Mouse Model of Alzheimer's Disease

Previously, we demonstrated that mitochondrial bioenergetic deficits preceded Alzheimer's disease (AD) pathology in the female triple-transgenic AD (3xTgAD) mouse model. In parallel, 3xTgAD mice exhibited elevated expression of ketogenic markers, indicating a compensatory mechanism for energy production in brain. This compensatory response to generate an alternative fuel source was temporary and diminished with disease progression. To determine whether this compensatory alternative fuel system could be sustained, we investigated the impact of 2-deoxy-D-glucose (2-DG), a compound known to induce ketogenesis, on bioenergetic function and AD pathology burden in brain. 6-month-old female 3xTgAD mice were fed either a regular diet (AIN-93G) or a diet containing 0.04% 2-DG for 7 weeks. 2-DG diet significantly increased serum ketone body level and brain expression of enzymes required for ketone body metabolism. The 2-DG-induced maintenance of mitochondrial bioenergetics was paralleled by simultaneous reduction in oxidative stress. Further, 2-DG treated mice exhibited a significant reduction of both amyloid precursor protein (APP) and amyloid beta (Aβ) oligomers, which was paralleled by significantly increased α-secretase and decreased γ-secretase expression, indicating that 2-DG induced a shift towards a non-amyloidogenic pathway. In addition, 2-DG increased expression of genes involved in Aβ clearance pathways, degradation, sequestering, and transport. Concomitant with increased bioenergetic capacity and reduced β-amyloid burden, 2-DG significantly increased expression of neurotrophic growth factors, BDNF and NGF. Results of these analyses demonstrate that dietary 2-DG treatment increased ketogenesis and ketone metabolism, enhanced mitochondrial bioenergetic capacity, reduced β-amyloid generation and increased mechanisms of β-amyloid clearance. Further, these data link bioenergetic capacity with β-amyloid generation and demonstrate that β-amyloid burden was dynamic and reversible, as 2-DG reduced activation of the amyloidogenic pathway and increased mechanisms of β-amyloid clearance. Collectively, these data provide preclinical evidence for dietary 2-DG as a disease-modifying intervention to delay progression of bioenergetic deficits in brain and associated β-amyloid burden

Role of microbial exopolysaccharides on moisture retention, texture and functionality of low-fat mozzarella cheeses

Capsular and ropy microbial exopolysaccharides (EPS) produced by selected strains of Streptococcus thermophilus were used to make low-fat mozzarella cheeses containing 6% fat in a small-scale pilot study. The effects of EPS on moisture retention and textural and functional characteristics were investigated over 28 days of storage at 4°C. Texture profile analysis (TPA), meltability, stretchability, and pizza bake performance were analysed. Control cheeses made with non-EPS strains had the lowest moisture content of 53.77%. Control cheeses exhibited poor meltability and stretchability and greater hardness, springiness and chewiness. Capsular and ropy EPS increased moisture retention in cheeses to 57.17% and 58.39%, respectively, and EPS was isolated from curd at 31.09 mg/g and 51.65 mg/g, respectively. Cheeses made with EPS were softer, showed lower degree of springiness and chewiness and exhibited better stretchability and meltability as compared to control cheeses, although meltability of capsular EPS cheeses was not significantly different to the control (p>0.05). Adhesiveness and cohesiveness were greater in EPS cheeses compared to control cheeses. Adhesiveness of the two types of EPS cheeses was similar, but cohesiveness was greater in ropy-EPS cheeses. Pizza bake performance was poor for all cheeses although those made with EPS showed greater Hunter L-values and lower a-values to signifying less scorching.link_to_subscribed_fulltex

Textural and functional changes in low-fat Mozzarella cheeses in relation to proteolysis and microstructure as influenced by the use of fat replacers, pre-acidification and EPS starter

The influence of exopolysaccharides (EPS), pre-acidification and use of two fat replacers, FR1 and FR2, on the textural and functional characteristics of Mozzarella cheeses were studied. Control cheeses made with EPS producing Streptococcus thermophilus 285 had the lowest moisture (52.84%) and yield while hardness and melt properties of these cheeses improved with storage. Addition of FR1 or FR2 and pre-acidification of milk increased the moisture content in cheeses. All cheeses were softer than the control. Cheeses made with FR1 exhibited the greatest stretch and melt; those made with FR2 showed poor stretch and melt. Each cheese showed a unique microstructure prior to, and after the hydration of the protein matrix. The rate of α- and β-casein proteolysis was greater in cheeses made with pre-acidified milk and those having higher moisture content. Pizza bake performance was improved with FR1, but FR2 cheeses had the least favourable bake characteristics. Coating cheese shreds with oil was necessary for adequate browning, melt and flow. © 2005 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Low-fat mozzarella as influenced by microbial exopolysaccharides, preacidification, and whey protein concentrate

Low-fat Mozzarella cheeses containing 6% fat were made by preacidification of milk, preacidification combined with exopolysaccharide- (EPS-) producing starter, used independently or as a coculture with non-EPS starter, and preacidification combined with whey protein concentrate (WPC) and EPS. The impact of these treatments on moisture retention, changes in texture profile analysis, cheese melt, stretch, and on pizza bake performance were investigated over 45 d of storage at 4°C. Preacidified cheeses without EPS (control) had the lowest moisture content (53.75%). These cheeses were hardest and exhibited greatest springiness and chewiness. The meltability and stretchability of these cheeses increased most during the first 28 d of storage. The moisture content in cheeses increased to 55.08, 54.79, and 55.82% with EPS starter (containing 41.18 mg/g of EPS), coculturing (containing 28.61 mg/g of EPS), and WPC (containing 44.23 mg/g of EPS), respectively. Exopolysaccharide reduced hardness, springiness, and chewiness of low-fat cheeses made with preacidified milk in general and such cheeses exhibited an increase in cohesiveness and meltability. Although stretch distance was similar in all cheeses, those containing EPS were softer than the control. Cocultured cheeses exhibited the greatest meltability. Cheeses containing WPC were softest in general; however, hardness remained unchanged over 45 d. Cheeses made with WPC had the least increase in meltability over time. Incorporation of WPC did not reduce surface scorching or increase shred fusion of cheese shreds during pizza baking; however, there was an improvement in these properties between d 7 and 45. Coating of the cheese shreds with oil was necessary for adequate browning, melt, and flow characteristics in all cheese types. © American Dairy Science Association, 2005.link_to_subscribed_fulltex

Texture characteristics and pizza bake properties of low-fat Mozzarella cheese as influenced by pre-acidification with citric acid and use of encapsulated and ropy exopolysaccharide producing cultures

Low-fat Mozzarella cheeses containing 6% fat were made by pre-acidification of milk with citric acid to pH 6.1 and using encapsulated ropy or non-ropy exopolysaccharide (EPS) producing Streptococcus thermophilus. Moisture retention, changes in texture profile analysis (TPA), meltability and stretchability of cheese, and changes in colour, surface scorching and shred fusion were analysed after baking over 90 days (d). Control cheeses and those made from pre-acidified milk without EPS cultures had the lowest moisture content at 54.84% and 55.28%, respectively. Control cheeses were hardest and their meltability and stretchability were initially low. Hardness was reduced and the melt and stretch distances increased with time. When baked, control cheeses showed incomplete shred fusion. Pre-acidification reduced hardness and increased meltability. Capsular- and ropy-EPS were quantified at 30.42 and 30.55 mg g-1 of cheese, respectively, and increased moisture retention in pre-acidified cheese to 56.67% and 56.21%, respectively. These cheeses were softer and exhibited lower springiness. Greater meltability was observed initially but became similar to control cheeses after 90 d of storage. When baked after 45 d of storage, cheeses containing EPS producing cultures showed improved shred fusion, meltability and a reduction in surface scorching. © 2006 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Effects of pH, temperature, supplementation with whey protein concentrate, and adjunct cultures on the production of exopolysaccharides by Streptococcus thermophilus 1275

Effects of pH, temperature, supplementation with whey protein concentrate (WPC), and non-EPS culture on the exopolysaccharide (EPS) production by Streptococcus thermophilus 1275 were studied. The organism was grown in 10% reconstituted skim milk (RSM) in a Biostat B fermenter for 24 h at various pH (4.5, 5.5 and 6.5) and temperatures (30, 37, 40, and 42°C), and supplementation with WPC 392, and non-EPS producing S. thermophilus 1303 and the amount of EPS produced were determined. Bacterial counts were enumerated and the concentrations of lactic acid, lactose, glucose, and galactose were also determined. A maximum of 406 mg/L of EPS was produced in RSM at 37°C after 24 h of fermentation at pH 4.08 when the pH was not controlled. A pH of 5.5 and temperature of 40°C were found to be optimal for EPS production by S. thermophilus 1275, yielding 458 mg/L. The EPS production increased when RSM was supplemented with WPC 392. At optimum pH and at 37°C with WPC supplementation, the level of EPS increased to 1029 mg/L. Co-culturing S. thermophilus 1275 with non-EPS S. thermophilus 1303 increased EPS production at 37°C and pH 5.5 to 832 mg/L. High temperature (42°C) reduced the amount of EPS production, and EPS production ceased at pH 4.5 when maintained constantly at this pH. The level of lactose utilization and lactic acid production depended on growth conditions of the organism. No glucose was detected, while galactose was found to accumulate in the medium.link_to_subscribed_fulltex

High power ultrasound processing in milk and dairy products

Ultrasound has been known to create material changes through physical and chemical reactions. The homogenization effect of ultrasound is one of the most recognizable traits of the technology. This chapter explores the dairy applications in response to ultrasound treatment in a more descriptive manner. The efficiency of ultrasonic sonication is driven by several other important factors in addition to frequency, such as power. Membrane technology is currently used in the dairy industry for a variety of applications, such as separation of milk components, concentration of protein levels for spray drying and more. The chapter focuses on the effects of ultrasound on bulk physical and functional properties of casein-containing systems and their respective secondary dairy products. Controlling the viscosity of dairy streams with ultrasound is one of the most promising applications to have recently emerged. The thermal stability of whey proteins during heating is a major continuing processing issue

Application of ultrasound to reduce viscosity and control the rate of age thickening of concentrated skim milk

Concentrated skim milk was treated with high intensity low frequency ultrasound (20 kHz) to lower viscosity through a process of acoustic cavitation. Batch sonication for 1 min at 40-80 W, and continuous treatment delivering an applied energy density of 4-7 J mL-1, reduced the viscosity of medium-heat skim milk concentrates containing 50-60% solids. Viscosity was reduced by approximately 10%, but this improved to >17% in highly viscous age thickened material. Sonication also changed the shear thinning behaviour at shear rates below 150 s-1. Although ultrasound lowered the viscosity of skim milk concentrated to ≥50% solids, the treatment could only delay the rate of thickening once the ageing process was established. It was only when ultrasound was activated during concentration that sonication prevented the viscosity of skim milk concentrates from increasing rapidly