Effect of pH on the functional behaviour of pea protein isolate–gum Arabic complexes

The functional behaviour (solubility, emulsifying and foaming properties) of pea protein isolate (PPI) and gum Arabic (GA) mixtures were investigated as a function of pH (4.30–2.40) within a region dominated by complex coacervation. Emulsion stability was also investigated using a one- and two-step emulsification approach. Complex coacervation was monitored by turbidimetric acid titration at a 2:1 PPI–GA ratio to reveal the formation of soluble (pH 4.23) and insoluble (pH 3.77) complexes, maximum biopolymer interactions (pH 3.60), and dissolution of complexes (pH 2.62). Emulsion stability was greater for mixed systems relative to PPI alone at pHs between 3.10 and 4.00, and in those prepared using the one-step method. Foam expansion was independent of both biopolymer content and pH, whereas foam stability was improved for the mixed system between pH 3.10 and 4.00. The pH-solubility minimum was broadened relative to PPI to more acidic pHs. Findings suggest that admixtures of PPI and GA under complexing conditions could represent a new blended food and/or biomaterial ingredient.     

Technical note: Development of a challenge model for Streptococcus uberis mastitis in dairy heifers

A challenge model for experimentally inducing Streptococcus uberis mastitis in bred dairy heifers was developed. Qualifying heifers (n = 7) exhibited antibody titers of < 1:10,000 against Strep. uberis antigens and were free of intramammary infections (IMI). Two contralateral quarters of each heifer were assigned to receive an infusion of Strep. uberis (1,000 to 2,000 cfu); remaining quarters served as unchallenged controls. For a successful challenge and infection, 3 of 4 consecutive mammary secretion samples had to culture positive for Strep. uberis. Six of the 7 heifers were challenged successfully in both infused quarters with a mean dose of 1,080 cfu; once confirmed, infections were treated with a one-time infusion of nonlactating cow therapy. Before challenge, mammary secretion leukocyte counts averaged 8.4 × 10⁶/mL in all quarters. At 24 h after challenge, leukocyte count increased to 18.4 × 10⁶/mL in challenged quarters, peaking on d 5 at 24.3 × 10⁶/mL; unchallenged quarters remained at ≤ 10.4 × 10⁶/mL, but increased to 15.2 × 10⁶/mL on d 7 and then decreased. Before challenge, macrophages predominated (81%) in mammary secretions followed by lymphocytes (15.3%) and neutrophils (3.7%). By 24 h after challenge, neutrophils increased in challenged quarters and predominated for the duration of the trial (65.3 to 70%), whereas macrophages predominated in unchallenged control quarters (65.2 to 75.2%). The challenge model was successful in establishing Strep. uberis IMI in 85.7% of animals, and IMI were controlled (100% cure) by administering nonlactating cow therapy. All heifers calved free of IMI and antimicrobial residues, with milk production similar to that of herd mates and with somatic cell counts (SCC) < 200,000 cells/mL.     

Food proteins: A review on their emulsifying properties using a structure–function approach

Proteins are of great interest due to their amphiphilic nature, which allows them to reduce the interfacial tension at the oil–water interface. The incorporation of proteins at the oil–water interface has allowed scientists to utilise them to form emulsions (O/W or W/O), which may be used in food formulations, drug and nutrient delivery. The systematic study of the proteins at the interface and the factors that affect their stability (i.e., conformation, pH, solvent conditions, and thermal treatment) has allowed for a broader use of these emulsions tailored for various applications. In this review, the factors affecting the stability of emulsions using food proteins will be discussed. The use of polysaccharides to complex with proteins will also be explored in relation to enhancing emulsion stability.     

Efficacy of .18% iodine teat dip against Staphylococcus aureus and Streptococcus agalactiae

Effective postmilking teat dip products with lower iodine concentrations are being formulated as concern increases about iodine residues in milk. Increased free iodine concentration with greater germicidal activity in teat dip products is also possible with special formulation procedures. Low iodine concentration dips are cheaper and have reduced teat irritation. A concentrated iodine teat dip containing .18% iodine and 8 ppm free iodine upon dilution was evaluated under experimental bacterial challenge to determine efficacy for prevention of new intramammary infections. The undiluted product also contained 15% collagen protein emollient as a teat skin conditioner. Efficacy of the teat dip was 93.6 and 51. 7% for Staphylococcus aureus (Newbould 305) and Streptococcus agalactiae (McDonald 44). No adverse effects of the dip on teat skin were noted.     

Data reduction techniques and hypothesis testing for analysis of benchmarking data

This paper proposes a data reduction and hypothesis testing methodology that can be used to perform hypothesis testing with data commonly collected in benchmarking studies. A reduced-form performance vector and reduced-form set of decision variables are constructed using the multivariate data reduction techniques of principal component analysis and exploratory factor analysis. Reductions in dependent and exogenous variables increase the available degrees of freedom, thereby facilitating the use of standard regression techniques. We demonstrate the methodology with data from a semiconductor production benchmarking study.     

Multi-continuum analysis of thermally induced matrix cracking

Matrix micro-cracking due to thermal loading is a major concern in composite cryogenic tanks because it presents permeation paths for the stored fluids and gases. Accurate prediction of composite damage due to micro-crack initiation is thus an important aspect of tank analysis and design. In the research presented, failure criteria are applied at both the composite (macro-) and constituent (micro-) scale in an effort to assess the most effective analysis techniques for predicting composite damage. Constituent scale information is developed using multi-continuum theory, a classic strain decomposition approach. Numerical predictions are correlated against experimental results.     

Null hypothesis significance testing: A review of an old and continuing controversy.

Null hypothesis significance testing (NHST) is arguably the most widely used approach to hypothesis evaluation among behavioral and social scientists. It is also very controversial. A major concern expressed by critics is that such testing is misunderstood by many of those who use it. Several other objections to its use have also been raised. In this article the author reviews and comments on the claimed misunderstandings as well as on other criticisms of the approach, and he notes arguments that have been advanced in support of NHST. Alternatives and supplements to NHST are considered, as are several related recommendations regarding the interpretation of experimental data. The concluding opinion is that NHST is easily misunderstood and misused but that when applied with good judgment it can be an effective aid to the interpretation of experimental data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinct mechanisms for the induction and maintenance of allograft tolerance with CTLA4-Fc treatment

A murine CTLA4/Fc gamma2a heavy chain (mCTLA4-Fc) chimeric fusion molecule was used in B6AF1 recipients of BALB/c pancreatic islet allografts to study the induction and maintenance of tolerance following inhibition of the CD28-B7 pathway for T cell activation. Donor-specific tolerance was achieved by administering 100 microg of mCTLA4-Fc on alternate days for 14 days (8 total doses) or a single 500 microg dose of mCTLA4-Fc on day 2 after transplant. Tolerance was mediated by long-lived peripheral lymphocytes and showed features of organ and alloantigen specificity. Whereas tolerance could not be established in allograft recipients receiving simultaneous mCTLA4-Fc and rIL-2, previously tolerant animals did not reject their grafts when given IL-2, suggesting that the induction and maintenance phases of tolerance were distinct and separate. The maintenance of donor-specific tolerance was an active immunologic process that was CD4+ T cell dependent and could be adoptively transferred to naive lymphocytes, but could not be explained by apoptosis or deletion of alloreactive T cells. Although an IL-2-sensitive mechanism such as anergy may contribute toward the induction of tolerance, its maintenance involves active suppression.