Rheological and Microstructural Characteristics of Canola Protein Isolate−Chitosan Complex Coacervates

Wastage of byproducts such as canola meal is a pressing environmental concern, and canola protein isolate (CPI)?chitosan (Ch) coacervates have a good potential to utilize and convert the wastes into a high value added product. Yet so far, there is very limited rheological and microstructural information to assist in proper utilization of CPI ‐Ch complex coacervates. The rheological and microstructural properties of the complex coacervates formed from CPI and chitosan Ch at various CPI‐to‐Ch mixing ratios (1:1, 16:1, 20:1, and 30:1) and pH values (5.0, 6.0, and 7.0) were therefore investigated. These CPI?Ch complex coacervate phases were found to exhibit elastic behavior as evidenced by significantly higher elastic modulus (G?) compared to viscous modulus (G″) in all the tested ratios and pH ranges. They also exhibited shear‐thinning behavior during viscous flow. The complex coacervates formed at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0 demonstrated the highest G?, G″, and shear viscosity, which correlated well with the high strength of electrostatic interaction and thick‐walled, sponge‐like, less‐porous microstructure at this condition. The higher shear viscosity of the coacervate at pH 6.0 was most likely induced by stronger attractive electrostatic interactions between CPI and Ch molecules, due to the formation of a rather densely packed complex coacervate structure. Hence, it can be concluded that the microstructural observations of denser structure correlated well with the rheological findings of stronger intermolecular bonds at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0. The complex coacervate phase formed at a CPI‐to‐Ch ratio of 16:1 and pH of 6.0 also showed glassy consistency at low temperatures and rubbery consistency above its glass‐transition temperature. This study identified the potential for the newly developed CPI–Ch complex coacervate to be used as an encapsulating material due to its favorable strength. This would drastically reduce the wastage of byproducts, provide a solution to tackle the pressing global issue of wastage of byproducts, and bring about a more environmentally friendly paradigm.     

Effect of dietary supplementation with heat-treated canola meal on ruminal nutrient metabolism in lactating dairy cows

An experiment was conducted to quantify the effects of incremental levels of heat-moisture-treated canola meal (TCM) fed to dairy cows on the relationship between ruminal nutrient digestion and milk production. Experimental diets were fed to 4 multiparous rumen-cannulated Nordic Red cows, averaging (mean ± standard deviation) 681 ± 54.8 kg of body weight, 111 ± 16 d in milk, and 29.1 ± 9.1 kg of milk/d at the start of the study, in a Latin square design with four 21-d periods. The 4 experimental dietary treatments consisted of a basal diet of grass silage and crimped barley, and 3 diets in which the crimped barley was replaced with TCM, giving 3 incremental levels of protein supplementation. Nutrient flow was quantified by the omasal sampling technique using 3 markers (Cr, Yb, and indigestible neutral detergent fiber). Continuous infusion of ¹⁵N was used to label bacterial crude protein. Additionally, ruminal sampling and evacuations and measurements of total-tract digestibility were conducted. The experimental diets provided 132, 148, 164, and 180 g of crude protein/kg of dry matter. The increased level of TCM linearly increased dry matter intake from 15.1 to 16.6 kg/d and energy-corrected milk yield from 21.0 to 25.6 kg/d. The increased proportion of TCM when substituting barley with TCM was associated with greater total-tract digestibility of neutral detergent fiber and potentially digestible neutral detergent fiber, which could be explained by increased digestion rate of potentially digestible neutral detergent fiber. Omasal flow of nonammonia N naturally increased with greater dietary TCM inclusion, but the increased intestinal supply of rumen-undegradable protein was partly offset by diminished microbial protein synthesis when feeding more TCM. This was also reflected in a decreased proportion of milk protein from ruminal bacterial protein when TCM supplementation increased.     

Incorporation of canola proteins extracted by electroactivated solutions in gluten‐free biscuit formulation of rice–buckwheat flour blend: assessment of quality characteristics and textural properties of the product

Canola proteins extracted by electroactivated solutions were incorporated to gluten‐free biscuits made from blend of rice and buckwheat flours. Physical and textural properties were significantly influenced by these proteins. Isolates and concentrates did not behave in a similar way. A significant increase in diameter was noted for all of the supplemented samples. An increase in thickness was observed for the samples added with protein concentrate, whereas the spread ratio decreased for all the samples compared to control. The hardness of biscuits decreased with the addition of the proteins as compared to the control. The changes in biscuit hardness or fracture strength were in line with the changes in dough hardness. Biscuits containing protein concentrate had lighter, more aerated texture as shown by scanning electron microscopy with lesser amounts of gelatinised starch, indicating improved gas‐holding capacity and more stabilised structure. Protein‐supplemented biscuits have lower moisture and water activity.     

Possible causes for decreased stability of canola oil processed from green seed

Canola oil extracted from seeds with a high-chlorophyll content can contain chlorophyll derivatives in excess of 30 ppm. When processed, this oil has been observed to be less stable than oil (typically containing 5 to 25 ppm chlorophyll) processed from high-grade seed. Possible causes for this phenomenon were investigated in this study. The effect of initial pheophytin content was examined by mixing fully saturated oil (tricapryloylglycerol) with increasing amounts of pheophytin and then by subjecting the mixtures to processing conditions. When the processed oils were combined with an unsaturated oil (canola oil), the oxidative stabilities decreased as the pre-processing content of pheophytin increased. Examination of the effect of increased bleaching to remove excessive levels of pheophytin showed that oil stability decreased with increasing exposure to bleaching clay. Additionally, processing treatments did not remove secondary autoxidation products from oil that was abused prior to processing. Such a finding revealed the importance of initial oil quality on processed oil stability, i.e., the greater abuse of the crude oil (resulting in greater contents of secondary oxidation products), the lower the stability of the processed oil. Finally, previous reports by other researchers of pheophytin's pro-oxidative effect in oil stored in light were confirmed.     

An overview of the phenolics of canola and rapeseed: Chemical,sensory and nutritional significance

Utilization of rapeseed meal in human foods has been thwarted by the presence of antinutritional factors such as glucosinolates, phenolics, phytates and hulls. The content of phenolics in rapeseed flour is nearly 30 times higher than that of soybean. Phenolic compounds contribute to the dark color, bitter taste and astringency of rapeseed meals. They may also interact with amino acids, enzymes and other food components, thus influencing the nutritional value of rapeseed meal and its products. Therefore, phenolic compounds are important factors when considering rapeseed meal as a protein source in food formulations. Available literature data on phenolic compounds and tannins of rapeseed/canola are fragmentary and diverse. Furthermore, developing a standardized method for analysis and quantitation of these compounds is warranted. Interaction of rapeseed phenolics/tannins with proteins and their effects on enzymes and other food components remain to be studied.     

A laboratory study of the press effect in adsorptive bleaching

The so-called press effect is widely credited with enhancing the overall efficiency of bleaching clays in commercial operations. Laboratory bleaches are generally done with one use of bleaching clay, while plant operations often include a process in which spent clay in a filter press acts as a fixed bed to remove additional impurities from slurry-treated oil. In this study, the press effect is simulated in the laboratory by measuring the influence of a progres-sively-built filter cake on concentrations of carotenes and chlorophyll in successive batches of slurry-contacted oils. The oil used was canola; the clay tested was a commercially available acid-activated clay classified to two different average particle sizes. Conditions were chosen to simulate those used in commercial operations. Better total bleaching was seen from the first batch to the last as filter cake was built up. In addition, a significant particle size effect was seen. Presented at the 83rd AOCS Annual Meeting and Exposition, Toronto, Ontario, Canada, May 10–14, 1992.     

Physical properties of lipase‐catalyzed interesterification of palm stearin with canola oil blends

Interesterified blends of hard palm stearin (IV of 11) and canola oil (hPS/CO) in ratios of 20 : 80, 30 : 70, 40 : 60, 50 : 50, 60 : 40 and 70 : 30 were prepared using immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM). Comparison of physical properties was carried out between non‐interesterified and enzymatically interesterified products by monitoring their slip melting point (SMP), solid fat content (SFC), melting thermogram and polymorphism behavior. The Lipozyme TL IM‐catalyzed interesterification significantly modified the physical properties of the hPS:CO blends. The results showed that all the interesterified blends had lower SMP and SFC than their unreacted blends. The SMP result showed that the interesterified blends of hPS/CO 40 : 60, 50 : 50 and 60 : 40 could be useful for stick margarine and shortening applications, respectively. From the SFC analysis, the interesterified blends of hPS/CO 40 : 60 have SFC curves similar to vanaspati. The interesterified blends of hPS/CO 50 : 50 and 60 : 40 have SFC curves similar to margarines, puff pastry margarine and shortening. Interesterification had replaced the higher‐ and lower‐melting triacylglycerols by the middle‐melting triacylglycerols, yielding mixtures of lower SMP and SFC, compared to the original palm stearin. X‐ray diffraction analysis indicated the appearance of β' crystals in all the interesterified hPS/CO blends from predominantly β‐type oils.     

Sensory stability of canola oil: Present status of shelf life studies

Sensory studies on autoxidation of canola oil, stored under several variations of Schaal Oven test conditions, suggest an induction period of 2–4 d at 60–65°C. Similar induction periods have been observed between canola and sunflower oils, whereas a longer induction period has been found for soybean oil. Canola oil seems to be more stable to storage in light than cottonseed and soybean oils but is less stable than sunflower oil. Storage stability of products fried in canola oil is similar to products fried in soybean oil. Storage stability of canola and cottonseed oils that had been used in the frying of potato chips showed that canola oil was more prone to autoxidation during storage at 40°C. The presence of light aggravated the oxidative effects and was similar for both oils. Advances in our knowledge about the shelf life of canola oil would be strengthened by standardization of Schaal Oven testing conditions and by specifying the testing protocol for photooxidation studies. Methods for training of panelists and for handling and evaluating oils and fried foods require definition. Rating scales used in the evaluation of oils need to be evaluated to ensure that reliable and valid measurements are achieved. Further progress is needed in the identification of chemical indicators that can be used to predict sensory quality of oils. Presented in part at AOCS Annual Meeting in Toronto, Ontario, Canada, May 1992.     

Formation and partial characterization of canola oil sediment

The occasional development of a haze in canola oil represents a problem to the quality and acceptability of this oil. The present study examined the formation of sediment in bottled canola oil during storage at 2, 6 and 12°C over a 4-d period. Oils stored at 2°C showed the highest rate of sediment formation, followed by storage at 6°C. Removal of sediment from canola oil prior to storage by cold precipitation and filtration did not eliminate this phenomenon, which still developed rapidly at 2°C. Chemical composition and thermal properties of canola oil sediment were compared to sediment obtained from commercial winterization of this oil. The thermal properties of the purified winterization sediment (melting temperature, 74.9°C) closely resembled those of the sediment from bottled canola oil. Saponification of both sediments yielded large amounts of long-chain fatty acids and alcohols, which were identified by gas chromatography-mass spectrometry. Sediment from commercial winterization contained higher amounts of fatty acids and alcohols with more than 24 carbon atoms in the chain. Presented in part at the AOCS meeting in Toronto, Ontario, May 1992.     

Comparison of visual and automated colorimeters—An international collaborative study

Color as a fundamental quality of edible oils has been determined primarily by visual comparison methods for many decades. The automatic colorimeters introduced recently made it possible to replace the manually operated visual color instrument, which requires experience to master and is often subject to operator variabilities. A previous study with an automatic colorimeter, Colourscan, to measure the colors of refined and refined bleached cottonseed oils showed good agreement (r ²=0.99) with visual color measurements by means of the Lovibond-AOCS Color Scale. The current work is to establish a broad-scale correlation between the automated colorimeter and visual color measurements. In this international effort, factory-processed refined and refined, bleached, deodorized (RBD) canola, corn, cottonseed, peanut, sunflower and soybean oils, as well as refined palm olein, RBD palm oil, and washed, dried, filtered and deodorized tallow were used. A total of 14 laboratories from the United States and Canada, and 16 laboratories from 12 countries outside of North America, participated in this collaborative study. The results of this study, with statistical analyses, are reported.