L.J. Rubin

The hexanal content as an indicator of oxidative stability and flavour acceptability in cooked ground pork

Abstract The hexanal content, flavour acceptability, and oxidative stability of meats treated with different additives were evaluated. The additives included sodium ascorbate, sodium tripolyphosphate, sodium nitrite, BHA, and TBHQ, individually or in combination. The results indicated that the hexanal content, sensory scores, and TBA numbers of treated meats were linearly interrelated. The correlation coefficient for the linear relationship between the relative hexanal content and the TBA numbers for meat cooked with different additves was 0.995. Flavour acceptability decreased as TBA numbers or hexanal content increased.

Degradation of wheat starch in a twin-screw extruder

Abstract Wheat starch was processed in a Baker-Perkins MPF-50D co-rotating twin-screw extruder, at moisture contents of 25% and 30%, screw speeds of 200 rpm and 300 rpm, feed rate of 30 kg/h, and barrel temperature settings of 100, 120, 140 and 160 °C. High performance size exclusion chromatography was used to determine the extent of degradation of starch along the extruder channel. Starch degradation was found to take place in the cooking zone. The first-order mechanodegradation models, which were developed for a single-screw extruder, were extended to the twin-screw extruder and improved by including a more accurate description of gelatinization in the model. The degradation is described by the equation: χ = 1 − {1 − exp [−k 0 exp (− (ΔE 0 − βτ) (RT) )t]} {1 − exp (−kτt + B)} where τ is the average shear stress, t is the mean residence time of the melt in the active zone of the screw channel, ΔE0 is the activation energy, R is the ideal gas constant, β is the activation volume, k and k0 are experimental constants.

Catalytic behavior of palladium in the hydrogenation of edible oils

Palladium supported on alumina was used to hydrogenate soybean and canola oil. Previous literature reports indicated that palladium forms moretrans isomers than nickel. At 750 psig, 50 ppm palladium, and at 70 C, only 9.4%trans were formed when canola oil was hydrogenated to IV 74. In general, high pressure and low temperature favored lowtrans formation with no appreciable loss in catalyst activity. The effect of pressure, temperature and catalyst concentration on reaction rate,trans formation and selectivity is presented. A survey of various catalyst supports is discussed. Apparent activation energies of 6.3 to 8.9 kcal/mol were obtained; they are in good agreement with values reported in the literature.

Effect of sequestering agents on lipid oxidation in cooked meats

Abstract To retard lipid oxidation, which affects the sensory and nutritional quality of cooked meats, a number of sequestering agents (ortho- and polyphosphates, citric acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), salicylic acid, the sodium salts of oxalic, phytic and lactic acids, glycine, cysteine, 8-hydroxy-quinoline and catechol) were added to ground pork prior to cooking. The TBA numbers of meat were evaluated after cooking (day 1) and after 7, 14, 21, 28 and 35 days of storage at 4°C by the 2-thiobarbituric acid (TBA) test. It was found that catechol, EDTA, DTPA, sodium pyrophosphate and, to a lesser extent, sodium tripolyphosphate, substantially lowered the TBA numbers while the other sequestering agents had only a marginal effect. Mixed-chelating systems composed of salicylic acid and either EDTA or DTPA did not show any synergistic effects.

Control of lipid oxidation in cooked meats by combinations of antioxidants and chelators

Abstract The degree of oxidation in cooked meats treated with phosphates or polyphosphates and sodium ascorbate (SA) or one of its related compounds was determined using the 2-thiobarbituric acid (TBA) test. Combinations of ascorbates with a polyphosphate effectively retarded lipid oxidation in cooked pork during a 5-week storage period at refrigerator temperature. Addition of a phenolic antioxidant—butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), tert -butylhydroquinone (TBHQ) or trihydroxybutyrophenone (THBP)—to the above mixtures did not affect the TBA numbers substantially (≤0·1 TBA unit). Ethylenediaminetetraacetic acid disodium salt (Na 2 EDTA) with sodium ascorbate, with or without a phenolic antioxidant, was effective in protecting cooked pork from oxidation (TBA numbers of ≤1). Commercial antioxidant systems, Tenox A and Tenox II, were also effective in retarding meat rancidity, but Ronoxan A and Ronoxan D20 were only slightly effective.

Heterogeneous catalytic hydrogenation of canola oil using palladium

The hydrogenation of canola oil was studied using palladium black as a potential catalyst for producing partially hydrogenated fats with lowtrans-isomer content. Pressure (150\s-750 psig) appeared to have the largest effect ontrans-isomer formation. At 750 psig, 90 C and 560 ppm metal concentration, a maximum of 18.7%trans isomers was obtained at IV 53. A nickel catalyst produces about 50%rans isomers at the same IV. For palladium black, the linolenate and linoleate selectivities were 1.2 and 2.7, respectively. The maximum level oftrans isomers observed ranged from 18.7% to 42.8% (150 psig). Temperature (30\s-90 C) and catalyst concentration (80\s-560 ppm) affected the reaction rate with little effect ontrans-isomer formation and selectivities. At 250 psig and 50 C, supported palladium (5% Pd/C) appeared to be twice as active as palladium black. At 560 ppm Pd, 5% Pd/C produced 30.2%trans (IV 67.5), versus 19.0%trans for palladium black (IV 68.9). Respective linoleate selectivities were 15 and 6.6, while linolenate selectivities were approximately unity. Analysis of the oil samples by neutron activation showedapproximately a 1 ppm, Pdresidue after filtration.

Preparation of Dinitrosyl Ferrohemochrome from Hemin and Sodium Nitrite

Abstract Dinitrosyl ferrohemochrome was synthesized from hemin, sodium nitrite and sodium dithionite. The purity of the pigment so obtained varied between 65 and 72%. Hemin, the precursor to this synthetic cooked cured-meat pigment was prepared from beef red blood cells using modified versions of the methods described by Schalfejeff or Labbe and Nishida. About 80-99% of the bloods hemin may be extracted using these modified methods of preparation.

The Alkanol-Ammonia-Water/Hexane Treatment of Canola

Abstract A new two-phase solvent extraction system was developed for the treatment of rapeseed (canola). The polar phase consisted of a lower alkanol containing 0-14% (w/w) of ammonia and 0-15% (v/v) of water. The non-polar phase was hexane. Of the alkanols, methanol was the most effective, followed by ethanol. Isopropanol and t-butanol were of limited usefulness. Methanol containing 5% water (v/v) and 10% ammonia (w/w) gave the best overall results at a solvent-to-seed (R) ratio of 6.7 (v/w) and a blending time of 2 min, followed by a quiescent period of 15 min. At this point hexane was added (R = 6.7) and the mixture stirred vigorously. The phases were separated by usual means. The hexane phase contained 79-89% of the oil present in the original seed. More oil could be extracted from the meal and the methanol phase. The oil-free meal was light in colour and bland in flavour. Its glucosinolate content was below the detection level of the analytical method employed.

Stabilization of meat lipids with nitrite-free curing mixtures

Several nitrite-free meat-curing mixtures have been formulated. The mixtures included salt, sugar, ascorbates, an antioxidant and/or a chelator, an antimicrobial agent and dinitrosyl ferrochemochrome (DNFH). They imparted to meat a similar oxidative stability as that of sodium nitrite. Butylated hydroxyanisole and t-butylhydroquinone were the best anti-oxidants and polyphosphates, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid were the superior chelators. The antimicrobial agents used were potassium sorbate, propryl paraben, fumarate esters and sodium hypophosphite. In the above mixtures, the added effect of (DNFH) on oxidative stability of the cooked meats was similar to the added effect of 150 ppm sodium nitrite.

A Novel Processing Approach for Rapeseed and Mustard Seed-Removal of Undesirable Constituents by Methanol-Ammonia

An overview of a novel two-phase solvent-extraction system developed for treatment of rapeseed and mustard seed in our laboratories will be presented. In this process, the polar phase consisted of a lower alkanol containing 5% water (v/v) and 10% ammonia (w/w). The non-polar phase was hexane. Of the alkanols, methanol was the most effective, followed by ethanol. Isopropanol and t-butanol were of limited usefulness. A meal with a protein content of about 50% was obtained, and there was essentially no loss of protein material. Its glucosinolate content was reduced by an order of magnitude. Over 2/3 of the phenolics were removed by CH3OH/NH3/H2O treatment; however, the phytates were not affected. The protein in the meal had lower solubility properties, but a very high fat absorption as compared with the protein in hexane-extracted meal. The oil obtained from this process was essentially free of phospholipids and may be considered as degummed.