Eight cereal products ranging from a fat-free ready- to-eat (RTE) cereal (frosted flakes) to a full-fat high- ratio cake mix were subjected to analyte separation by anhydrous diethyl ether extraction (EE), acid hydrolysis/mixed ether extraction (AH), solid-phase extraction (SPE), and supercritical fluid extraction (SFE) with CO2 and with CO2 modified with 15% ethanol (SFEmod). Gravimetric analyses of extracts indicated higher (P ≤ 0.05) crude fat values by AH than by EE, SFE, or SFEmod. Extractions followed by fatty acid methyl ester analysis also produced higher (P ≤ 0.05) triglyceride means by AH than by other methods used for heat-treated RTE cereals and for ready-to-cook (RTC) cream of wheat. Therefore, for labeling purposes, AH seems most appropriate because in most cases it achieves higher triglyceride values than extraction with solvent(s) alone. SFE and SPE, on the other hand, yield fat values similar to those obtained by EE and offer the advantages of reduced solvent volume, short extraction times, and ease of laboratory automation.
Acrolein (2-propenal) and other low molecular weight aldehydes (LMWAs) formed by degradation of the frying medium (triglycerides) were monitored by liquid chromatography (LC) during preparation of fried items. LMWA contents of coatings from codfish and of doughnuts and their volatiles that codistill with steam are monitored by trapping the vapors and distillate from the food matrix in a 2,4-dinitrophenylhydrazine solution. The resulting hydrazones are partitioned from the aqueous phase, first into isooctane and then into acetonitrile for LC analysis. The hydrazones are separated and quantified on a C18 reversed-phase column with acetonitrile-water as the mobile phase. LMWAs are confirmed by gas chromatography/mass spectrometry. No difference was found in LMWA content in coatings from fish fillets fried at 182 or 204°C. Cake doughnuts were higher in acrolein content than yeast-raised doughnuts prepared under similar conditions. Freshness of the frying medium, frying time, and batch size did not seem to influence LMWA production from doughnuts. Results indicated that most of the LMWAs formed codistilled with steam during frying rather than remaining with the food item.
Relationship between viscosity and pickup (percent coating weight) of a fish and chip batter was examined with respect to the following parameters: (1) protein content of wheat flour used, (2) batter temperature, and (3) batter holding time. Results obtained indicated that a statistically significant (P < 0.001) correlation existed between viscosity and: (1) wheat flour protein content (r = 0.96), (2) percent pickup (r = 0.90), and (3) batter temperature (r = -0.62). Results also indicated that protein content of the wheat flour ingredient and batter temperature may be used as indicators of batter viscosity and, subsequently, percent pickup in the operation of battering portion-controlled codfish fillets.
The effects of two thermal processes and two cooking methods (broiling and microwave) on natural residues of DDT and its metabolites in beef were studied. Residue analysis was performed by aluminum oxide cleanup of fat and electron capture gas chromatography. Similar residue losses resulted from broiling, microwave preparation, and processing beef at 104°C for 342 min. Less residue loss occurred when beef was processed at 127°C for 66 min.
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