Water vapour permeability of edible bilayer films of wheat gluten and lipids

Various formulations and methods of fabricating edible bilayer films consisting of wheat gluten as a structural layer and a thin lipid layer as a moisture barrier were investigated and examined for water vapour permeability. Solid lipids such as beeswax or paraffin wax deposited in a molten state onto the base film were the most effective water vapour barriers. A film consisting of wheat gluten, glycerol and diacetyl tartaric ester of monoglyceride as one layer, and beeswax as the other yielded a water vapour permeability of 0.0048 g mm m⁻² mmHg⁻¹ 24h⁻¹, which was less than that obtained with low density polyethylene.     

Dairy research in Canadian universities

The research activities in dairy science at the University of Guelph, Université Laval, and the University of Alberta are presented. At the University of Guelph, the Ontario dairy industry (producers and processors) and the federal government sponsor two dairy research chairs, one in dairy chemistry/technology and the other in dairy microbiology/food safety. This activity is complemented by other food science faculty with dairy research interests. At Université Laval, the dairy research group STELA, comprised of several faculty and support staff, focuses on the chemistry and technology of milk proteins, milk lipids and lactic acid fermentations. The University of Alberta also supports an active dairy research group. Dairy research is very strong at these institutions due to very proactive funding arrangements with dairy industry groups.     

VIRULENCE LEVELS OF BIOFILM-GROWN LISTERIA MONOCYTOGENES LO28 ARE LOWER THAN THOSE OF PLANKTONIC CELLS IN AN ORAL INOCULATION TEST ON MICE

The aim of this study was to produce Listeria monocytogenes biofilms suitable for virulence assays and to determine whether the released bacteria had the same virulence potential as their planktonic counterparts. Biofilms of Listeria monocytogenes LO28 strain, with or without Sphingomonas paucimobilis CCL10 strain, containing up to 7 log₁₀ cfu/cm² were produced in polypropylene syringes. The virulence of strain LO28 was analyzed in mice after intravenous, subcutaneous and oral inoculation. Its virulence level in binary cultures was not significantly different from that of monocultures. L. monocytogenes LO28 virulence in biofilms was lower than that of their planktonic counterparts after oral inoculation. Our results suggest that biofilms pose no greater health risk to the consumer than planktonic bacteria.     

Acid Milk Gel Formation as Affected by Total Solids Content

Reconstituted skim milk with varying concentrations of total solids was coagulated using glucono-δ-lactone (GDL). Microscopic, turbidimetric and rheological procedures were used to examine mineral solubilization, buffering capacity, casein dissociation and micellar solvation during gelation. Total solids of the milk affected pH of the onset of gelation attributable to differences in colloïdal calcium phosphate in the casein particles during acidification. Firmness and elasticity of the resulting gel increased with total solids from a more direct contribution of dry matter during the last stage of acid milk gel formation.     

An experimental approach for removing caseins from bovine colostrum using anionic polysaccharides

In this study, we assessed the effect of anionic polysaccharides on removing caseins from a commercial bovine colostrum solution. λ-Carrageenan and pectin were selected based on preliminary results indicating that they can produce serocolostrum. The electrophoresis profiles of the supernatants of the colostrum/polysaccharide mixtures revealed that all caseins, except κ-casein, began precipitating at a pectin concentration of 0.3%[w/v] and a λ-carrageenan concentration of 0.08%[w/v]. When the pH of the mixtures was adjusted to the initial pH of the colostrum, pectin reduced the amount of protein in serocolostrum by approximately 30% whereas it reduced the amount by 50% when the pH was not adjusted.     

Composition of Apricot Aroma: Correlations between Sensory and Instrumental Data

Volatile compounds of six apricot cultivars were isolated by vacuum distillation and separated by gas-chromatography. Eleven aromatic compounds were selected by sniffing and quantified after addition of known amounts of pure compounds. Sensory analyses were performed to rate the typicality of apricot aroma in these cultivars. Since the chemical extracts were not assessed significantly different from the raw product, statistical analyses were performed to correlate the typical sensory notes with the instrumental data. A correspondence analysis showed that cultivars could be separated into three clusters, according to their typical aroma. Hexyl acetate, γ-octalactone and γ-decalactone were shown to be key compounds for the apricot flavor whereas benzaldehyde could have a negative impact on the aroma of the less aromatic cultivars but would favorably complete the typical aroma of “Rouge du Roussillon.”     

IDENTIFYING OBJECTIVE CHARACTERISTICS THAT PREDICT CLUSTERS PRODUCED BY SENSORY ATTRIBUTES IN COOKED RICE

From eight samples of raw-milled, 10 samples of parboiled and 2 samples of canned rice, appearance, texture and flavour were determined sensorily and related to instrumental parameters and clusters of different types of rice having common sensory perceptions were identified. The physico-chemical characteristics, enthalpy of amylose-lipid complex I, protein content, length of raw grain, elastic recovery, water uptake and the viscoelastic index, varied widely between rice samples. The most discriminatory sensory attributes were appearance and texture characteristics such as 'brown', 'elastic', 'long', 'firm' and 'shiny'. The instrumental measurements were highly correlated with sensory parameters. Parboiled rice samples, characterised by a brown colour, an elastic—firm—smooth texture and a broth flavour, were different from the raw-milled rice samples described as 'juicy', 'melting', 'shiny', 'aggregated and swollen grains', 'starch and milk' flavour. Canned rice samples were distinguished by a 'jute and earth' flavour, 'bitterness' and the presence of 'foreign matter'. Five clusters of types of rice could be distinguished which were characterised by a soft texture for the first, by a sticky-pasty texture for the second, by a brioche flavour and medium intensity characteristics of sticky and melting texture for the third, by the length of grain and a slight crunchy texture for the fourth, and by the firmness and elasticity for the last cluster. Five instrumental determined characteristics, enthalpy of amylose-lipid complex I, thickness of cooked grain, water uptake, browness index and protein content classed each rice into one of these 5 clusters with an error of 4%.