Camelina sativa oil (CO) is characterized by a high content (up to 40 wt %) of essential a-linolenic acid and characteristic odour and flavour. Deodorization of highly unsaturated oils requires great attention as the refining process involves thermal treatment which affects oil integrity. In the present study RSM and principal component analysis (PCA) were used to optimize bench-scale deodorization of CO. Mathematical models were generated through multiple regressions with backward elimination, describing the effects of process parameters (temperature, steam flow, time) on oil quality indicators [peroxide value (PV), p-anisidine value (p-AV), g-tocopherol (g-T) and oxidative stability (OS)]. Additionally, sensory evaluation was performed. RSM analysis showed a significant effect of deodorization temperature and to a lesser extent, deodorization steam flow and time on removal of oxidative compounds, flavour and odour. PCA of chemical and sensory results showed that deodorization temperature affected the sensory properties in the samples. The best conditions for removing undesirable flavour and odour were achieved by using a deodorization temperature of 195-2108C.
Camelina sativa oil is characterized by its high content (up to 40 wt%) of a-linolenic acid and its unique flavor. It is considered to have beneficial health properties and is suitable for food and cosmetic uses. In the present study, response surface methodology was used to optimize processing parameters for bench-scale deodorization of camelina oil. The mathematical models generated described the effects of process parameters (temperature, steam flow, time) on several deodorization quality indicators: free fatty acids (FFA), trans fatty acids (TFA), color, and polymerized triglycerides (PTG). These newly established models can be used as a tool to identify optimum deodorization process conditions within chosen constraints. Based on the optimization of minimum retained FFA with the constraint of a maximum allowable TFA, deodorization parameters can be defined. At a constant steam flow rate of 42 ml/h, a temperature range of 210-220°C, and deodorization time of 70-120 min were defined. 220°C appears to be a critical upper temperature limit; above this temperature, isomerization rates significantly increase.
In this study, two different groups of fat samples were prepared in a way that samples of each group had different trans fatty acid (TFA) composition but similar solid fat content (SFC). Samples of the first group (named group A) had TFA between 0.0 and 56.23 %, while the samples of the second group (group B) contained trans isomers ranging from 0.0 to 44.4 %. A polarized microscope was used to monitor the differences between the samples in terms of crystal size and crystal number during isothermal crystallization. In general, increasing TFA resulted in formation of larger crystals in a shorter time. Similar findings were also observed when small deformation time and frequency sweep experiments were conducted. A higher TFA content led to higher complex modulus values during isothermal crystallization. On the other hand, when the samples were stored at 4 °C for 48 h, the samples with the lower trans isomer had higher hardness values.
In this study, the degree of inhomogeneity in crystallized fat samples was evaluated in terms of texture, solid fat content, microstructure, and triacylglycerol (TAG) composition. Four different cocoa butter alternatives based on symmetric or asymmetric monounsaturated TAGs and with different contents of palmitic acid (a POP-rich fat and a PPO-rich fat) and steric acid (a SOS-rich fat and a PSO-rich fat) were studied. Significant differences (P < 0.001) in hardness between top and bottom was observed for all fats except the PSO-rich fat. The inhomogeneous consistency was shown to be a consequence of microstructural variation within the crystallized fats. No differences in solid to liquid ratio, melting points, or polymorphic behavior between top and bottom of fats were found. Sedimentation during the crystallization process could explain the observed inhomogeneity. Although sedimentation most likely is limited to the early stages of the crystallization process due to network formation, sedimented crystals influence the crystallization kinetics and thus introduce microstructural variations. This hypothesis is supported by findings of a higher amount of trisaturated TAGs in the bottom compared with the top of crystallized fats. The PSO-rich fat crystallizes fast compared with the other evaluated fats, which explains the more homogeneous texture of the PSO-rich fat compared with the other evaluated fats.Practical applications: Fat crystallization plays an important role for the texture of many food products such as chocolates, confectioneries, margarine, and butter. Correct analysis of texture is thus critical when evaluating fats for the food industry. This study emphasizes that inhomogeneity in the consistency could be of practical importance for evaluation of the mechanical and textural properties of crystallized fats for instance by compression tests or small deformation rheological testing of fat samples prepared in molds or with needle penetration tests, which only include the top of a fat sample.
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