LIPID OXIDATION AND SENSORY CHARACTERISTICS OF FRESH AND CURED SAUSAGES FROM α-LINOLENIC ACID ENRICHED PORK

Forty-eight female piglets were raised with four levels of α-linolenic acid (0, 1.5, 2.5, 3.5%) to determine the effect of dietary fat on the fatty acid composition, sensory and storage stability of pork products. The degree of polyunsaturation in neutral lipids and phospholipids were increased significantly by the dietary LNA. The thiobarbituric acid reactive substances (TBARS) vaues of freshly prepared breakfast sausages with vacuum packaging remained low, but those of the loosely packaged, i. e., nonvacuumized, sausages increased more than 3 times during the 48 h storage period. The TBARS values of breakfast sausages frozen-stored for 3 months showed extensive lipid oxidation. The dietary LNA treatments and packaging had significant effects on the susceptibility of breakfast sausages to lipid oxidation. However, the oxidative stability of cured products was not affected by the dietary treatments. The results indicated that the pork enriched with polyunsaturated fatty acids could be used in cured products or uncured meat products protected by ‘hot vacuum packaging’without any sensory or quality deterioration due to lipid oxidation.     

THE EFFECTS OF DIETARY α-TOCOPHEROL AND SURFACE APPLICATION OF OLEORESIN ROSEMARY ON LIPID OXIDATION AND CHOLESTEROL OXIDE FORMATION IN COOKED RAINBOW TROUT (Oncorhynchus mykiss) MUSCLE

The inhibitory effect of dietary α-tocopherol supplementation (100 and 500 mg α-tocopheryl acetate/kg diet) and an oleoresin rosemary dip on lipid and cholesterol oxidation in cooked rainbow trout ( Oncorhynchus mykiss ) during storage at 4C for 48 h was investigated. The 2-thiobarbituric acid-reactive substances (TBARS) values of cooked fish muscle increased during storage for all treatments. Dietary α-tocopherol supplementation partially inhibited lipid oxidation. Surface application of oleoresin rosemary further enhanced this protective effect. Cholesterol oxides were formed in all the samples following cooking and storage. The major cholesterol oxidation products (COPS) were identified as 7 β-hydroxycholesterol, α- and β-epoxides, and 7-ketocholesterol. Formation of COPS was reduced by dietary supplementation with α-tocopherol and surface application of oleoresin rosemary. Statistical analysis revealed a highly significant (p < 0.01) inhibitory effect of oleoresin rosemary on COPS formation.     

INFLUENCE OF DIETARY MENHADEN FISH OIL ON FATTY ACID COMPOSITION OF THE EGG

The influence of menhaden fish oil and other oils on the fatty acid composition of the egg was studied. Diets containing 1.5% menhaden oil, 1.5% corn oil and no oil added were fed to 50 hens. The menhaden oil diet increased the composition of C_14:0, C_16:1, C_18:1, C_18:3w3, C_20:5w3 and C_22:6w3 in the eggs but decreased C_18:2w6 and C_20:4w6 compared with the corn oil diet. The concentration of C_20:5w3 was greater than C_22:6w3 in menhaden oil, but more C_22:6w3 was found in eggs than C_22:6w3. A significant increase in total w-3 PUFAs (polyunsaturated fatty acids) occurred in the eggs after feeding the menhaden oil diet for 5 days and the concentration continued to increase through day 15. Dietary fats tend to produce a fatty acid pattern in eggs similar to that of the diet and varies with the oil source concentration. Most fatty acid profiles in egg yolks were altered within 15 days after hens began to consume test diets.     

THE EFFECTS OF TBHQ AND α-TOCOPHEROL ON QUALITY CHARACTERISTICS OF REFINED-BLEACHED AND DEODORIZED PALM OLEIN (RBDPO) DURING DEEP-FAT FRYING

The changes in quality characteristics of refined, bleached and deodorized palm olein (RBDPO) during deep-fat frying for 5h/day for 5 consecutive days in four systems were compared. The four systems were RBDPO without antioxidant (system 1); RBDPO with 200 ppm TBHQ (system 2); RBDPO with 100 ppm TBHQ + 100 ppm α-tocopherol (system 3); and RBDPO with 200 ppm a-tocopherol (system 4). The addition of the antioxidants reduced peroxide value, anisidine value, free fatty acids, polar components, polymer content, the rate of the changes in iodine value and the rate of oxidation of C18:2. Adding antioxidants, however, caused darkening of the oil and increased the formation of foam during deep-fat frying.     

EFFECTS OF LACTIC ACID IN PROCESSING WATERS ON THE INCIDENCE OF SALMONELLAE ON BROILERS1

Commercial broilers were inoculated with 10⁵-10⁶/mL Salmonella typhimurium in the drinking water at 14, 10, 7, 4, and 2 days prior to processing. At 49 days of age, broilers were processed in a pilot processing facility. In additional trials, commercially-obtained pre- and post-chill carcasses were subjected to microbiological testing. Lactic acid (LA) (1%) was added to the scald and/or chill waters or to pre- (2%) or post-chill (1%) dips to reduce microbial contamination on ready-to-cook carcasses. In each trial, 12 carcasses per treatment were sampled for the presence of salmonellae (inoculated serotype and/or indigenous organisms) using a whole carcass rinse technique. The dip applications evaluated included 1 and 2% LA at various temperatures and exposure periods. Two control treatments which were not subjected to LA but were processed and handled similar to treated carcasses were evaluated for each trial conducted. Treatments that consistently resulted in reduced levels of salmonellae on carcasses included LA treatment (1%) in the chill water, a pre-chill dip (2% for 2 min at 37 C), 1% LA as a post-chill dip (≥60 s at 1.1 C), and 2% LA as a pre-chill dip (60 s at 37 C). All picked carcasses treated with LA exhibited mild skin discoloration, particularly in the highly pigmented areas.     

PREPARATION AND CHARACTERIZATION OF α-AMYLASE IMMOBILIZED ON COLLAGEN MEMBRANES

Crystalline pancreatic α-amylase was codispersed with hide collagen at pH 4.0 and tanned to form a membrane which degraded starch. The optimum pH for the codispersed membrane preparation was at pH 7.0 in contrast to the soluble enzyme which was as active at pH 8.0 as at pH 7.0. The immobilized enzyme responded maximally to 0.22M chloride whereas 0.02M chloride gave optimum rates for the soluble enzyme. The immobilized enzyme resisted thermal inactivation better than the soluble α-amylase. Raising the temperatures from 30 ° to 50 °C produced a 500% increase in rate for the bound enzyme. It was also demonstrated that membranes retained greater activity when stored in starch solution than in water. The effect of glutaraldehyde concentration on membrane activity was also studied.     

EFFECTS OF α-CHACONINE ON BRAIN BIOGENIC AMINES, ELECTROENCEPHALOGRAM, CARDIAC RATES AND RESPIRATORY RESPONSE IN RATS

Effects of various doses of α-chaconine were examined in the central nervous system by electrophysiological tests and by determining levels of several neurotransmitters. Assays of acetylcholine, norepinephrine, dopamine, serotonin, and the serotonin metabolite, 5-hydroxyindoleacetic acid, failed to show significant trends following intraperitoneal injections of up to 20 mg/kg α-chaconine. Symptoms observed at relatively low doses (8 or 10 mg/kg) included sedation, respiratory impairment, and constriction of abdominal muscles. At the same dosage the electroencephalogram pattern showed a significant increase in the proportion of low-frequency activity. Tachycardia was observed at both low (10 mg/kg) and high doses (40 mg/kg), whereas intermediate doses (20 or 30 mg/kg) were associated with bradycardia. Unchanged acetylcholine levels after α-chaconine administration did not correlate with previous reports of brain cholinesterase inhibition produced by α-chaconine.     

EFFECT OF SEVERAL EXPERIMENTAL PARAMETERS ON COMBINATION OF RED KIDNEY BEAN (PHASEOLUS VULGARIS) α-AMYLASE INHIBITOR WITH PORCINE PANCREATIC α-AMYLASE

Purified red kidney bean (Phaseolus vulgaris) amylase inhibitor forms a 1:1 stoichiometric complex with porcine pancreatic α-amylase leading to complete loss of enzyme activity on starch. Rate of complex formation is pH dependent and is maximal at pH 5. The rate constants for complex formation, as measured by loss of amylase activity, were 2.85 × 10⁴ M^-1 sec^-1 at pH 6.9 (ionic strength of 0.918) and 2.55 × 10⁵ M^-1 sec^-1 at pH 5 at 30°C. At pH 6.9, rate of complex formation was 4.8 times faster at 0.918 ionic strength as compared with the rate at 0.138 ionic strength. At 30°C, pH 6.9 and ionic strength of 0.168 the dissociation constant of the enzyme-inhibitor complex was determined to be 3.5 × 10^-11 M. The rate constant for dissociation of the complex was calculated to be 8.7 × 10^-8 sec^-1 under the same conditions. The rate constant for complex formation, at ionic strength of 0.168, was 1.1 × 10⁴ M^-1 sec^-1 at 37⁰ and 9.77 × 10² M^-1 sec^-1 at 25.7°C. The calculated activation energy for complex formation is 39.5 kcal/mole suggesting a rate-controlling conformational change. Oxidation of the carbohydrate moiety of the glycoprotein inhibitor caused complete loss of activity. Maltose, a competitive inhibitor of α-amylase, bound as readily to the enzyme-inhibitor complex as to free α-amylase. Trypsinized α-amylase, although still able to bind to Sephadex, did not bind inhibitor. The experiments with maltose and trypsinized amylase suggest the inhibitor may not bind at the active site of α-amylase.     

THE EFFECTS OF β-METHYLGLUCOSE, 3-0-METHYLGLUCOSE and THIOGLUCOSE ON AFLATOXIN PRODUCTION BY ASPERGILLUS PARASTICUS

Earlier work characterizing the effects of glucose analogs on growth and aflatoxin production by Aspergillus parasiticus was expanded by assessing the effects of β-methylglucose (βMG), 3-0-methylglucose (3MG) and thioglucose (TG). As sole carbon source of conidia-initiated cultures, βMG and 3MG, but not TG, supported growth, but none supported toxin production. In glucose-containing replacement cultures, MG appeared to stimulate toxin production, while TG was inhibitory and 3MG had no effect. Preliminary assessment of the effects of βMG, 3MG, TG, 2-deoxyglucose and α-methylglucose on glucose uptake and utilization by glucose-containing replacement cultures indicated that under conditions that favor aflatoxin production, none of the analogs inhibited the uptake of ¹⁴C-labelled glucose. It appears that the glucose transport system(s) of A. parasiticus may be unusual in that it is insensitive to a variety of glucose analogs.