Abstract: Objectives/Hypotheses: The adverse health effect potential of dietary lipid oxidation products (LOPs) has evoked much clinical interest. Therefore, we employed a 1H NMR-linked Principal Component Regression (PCR) chemometrics modelling strategy to explore relationships between data matrices comprising (1) aldehydic LOP concentrations generated in culinary oils/fats when exposed to laboratory-simulated shallow frying practices, and (2) the prior saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acid (PUFA) contents of such frying media (FM), together with their heating time-points at a standard frying temperature (180 oC). Methods: Corn, sunflower, extra virgin olive, rapeseed, linseed, canola, coconut and MUFA-rich algae frying oils, together with butter and lard, were heated according to laboratory-simulated shallow-frying episodes at 180 oC, and FM samples were collected at time-points of 0, 5, 10, 20, 30, 60, and 90 min. (n = 6 replicates per sample). Aldehydes were determined by 1H NMR analysis (Bruker AV 400 MHz spectrometer). The first (dependent output variable) PCR data matrix comprised aldehyde concentration scores vectors (PC1* and PC2*), whilst the second (predictor) one incorporated those from the fatty acid content/heating time variables (PC1-PC4) and their first-order interactions. Results: Structurally complex trans,trans- and cis,trans-alka-2,4-dienals, 4,5-epxy-trans-2-alkenals and 4-hydroxy-/4-hydroperoxy-trans-2-alkenals (group I aldehydes predominantly arising from PUFA peroxidation) strongly and positively loaded on PC1*, whereas n-alkanals and trans-2-alkenals (group II aldehydes derived from both MUFA and PUFA hydroperoxides) strongly and positively loaded on PC2*. PCR analysis of these scores vectors (SVs) demonstrated that PCs 1 (positively-loaded linoleoylglycerols and [linoleoylglycerol]:[SFA] content ratio), 2 (positively-loaded oleoylglycerols and negatively-loaded SFAs), 3 (positively-loaded linolenoylglycerols and [PUFA]:[SFA] content ratios), and 4 (exclusively orthogonal sampling time-points) all powerfully contributed to aldehydic PC1* SVs (p 10-3 to < 10-9), as did all PC1-3 x PC4 interaction ones (p 10-5 to < 10-9). PC2* was also markedly dependent on all the above PC SVs (PC2 > PC1 and PC3), and the interactions of PC1 and PC2 with PC4 (p < 10-9 in each case), but not the PC3 x PC4 contribution. Conclusions: NMR-linked PCR analysis is a valuable strategy for (1) modelling the generation of aldehydic LOPs in heated cooking oils and other FM, and (2) tracking their unsaturated fatty acid (UFA) triacylglycerol sources therein.
Abstract: A feeding experiment was conducted to determine the
optimum dietary protein and lipid levels for juvenile fancy carp. Eight
experimental diets were formulated to contain four protein levels (200,
300, 400 and 500 g kg-1) with two lipid levels (70 and 140 g kg-1).
Triplicate groups of fish (initial weight, 12.1±0.2 g fish-1) were
hand-fed the diets to apparent satiation for 8 weeks. Fish growth
performance, feed utilization and feed intake were significantly
(P0.05). Weight gain and feed efficiency ratio tended to
increase as dietary protein level increased up to 400 and 500 g kg-1,
respectively. Daily feed intake of fish decreased with increasing
dietary protein level and that of fish fed diet contained 500 g kg-1
protein was significantly lower than other fish groups. The protein
efficiency ratio of fish fed 400 and 500 g kg-1 protein was lower than
that of fish fed 200 and 300 g kg-1 protein. Moisture, crude protein and
crude lipid contents of muscle and liver were significantly affected by
dietary protein, but not by dietary lipid level (P>0.05). The increase in
dietary lipid level resulted in an increase in linoleic acid in liver and
muscle paralleled with a decrease in n-3 highly unsaturated fatty acids
content in muscle of fish. In considering these results, it was concluded
that the diet containing 400 g kg-1 protein with 70 g kg-1 lipid level is
optimal for growth and efficient feed utilization of juvenile fancy carp.