Liquid Chromatographic Determination of Residual Nitrite/Nitrate in Foods: NMKL Collaborative Study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.

The characterization of the most-liked reduced-fat Havarti-type cheeses

In Finland, official recommendations state that reduced-fat cheese should be used in the everyday diet. Finnish consumers are increasingly willing to consume food with a reduced fat content, and sales of reduced-fat cheeses have been increasing. The consumers who participated in this study (n=153; 17 to 78 yr old) ate reduced-fat cheeses on a weekly basis. They were recruited from supermarket customers living in a metropolitan area in Finland. The object of this study was to determine which kind of reduced-fat Havarti-type cheeses were most liked. The study consisted of a consumer test, sensory descriptive analysis, and chemical analysis of commercial reduced-fat Havarti-type cheeses (n=10). The results of the sensory quantitative descriptive analysis were compared with consumer hedonic ratings by external preference mapping. In addition, information on composition (fat, salt, and free amino acids) was gathered and compared with the hedonic ratings. The preferred sensory properties were a pale appearance, sticky texture, and rich flavor. However, the consumers could be grouped according to their preferences on appearance and consistency. The main attributes contributing to the grouping of consumers were stickiness, hardness, and yellow color. The least preferred cheeses among all Finnish consumers were those with the lowest flavor intensities. The consumers preferred the cheeses with the highest salt content.

Dry sausage fermented by Lactobacillus rhamnosus strains

The ability of three probiotic Lactobacillus rhamnosus strains GG, E-97800 and LC-705 and one commercial Pediococcus pentosaceus starter strain (control) to produce dry sausage was studied. During the fermentation process the numbers of inoculated lactic acid bacteria increased from approx. 7 log10 to 8-9 log10 cfu/g and the pH values decreased from 5.6 to 4.9-5.0. The sensory test indicated that the dry sausages fermented by L. rhamnosus LC-705 were inferior to the control sausages. The presence of inoculated experimental strains as predominant organisms in the dry sausages was recognised on the basis of their genetic fingerprints by ribotyping. The concentrations of biogenic amines remained low during the ripening process. These results indicated that the studied Lactobacillus rhamnosus strains, especially strains GG and E-97800, are suitable for use as probiotic starter cultures in fermenting dry sausage.

Application of liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and tandem mass spectrometry to the determination of volatile nitrosamines in dry sausages

A high-performance liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric method was developed for the determination of volatile nitrosamines in dry sausages. Tandem mass spectrometry was applied for the detection of N-nitrosopyrrolidine, N-nitrosodiethylamine and N-nitrosopiperidine. N-nitrosomethylamine was detected by using the selected ion monitoring mode. The occurrence of the four different nitrosamines was monitored in 27 dry sausage samples and a correlation was observed between N-nitrosopyrrolidine and biogenic amines. Nitroso compounds are thus not only formed in heated conditions but formation can also occur during ripening of dry sausages by reaction between residual nitrite and amines formed during the fermentation process.

Sodium nitrite and potassium nitrate in control of nonproteolytic Clostridium botulinum outgrowth and toxigenesis in vacuum-packed cold-smoked rainbow trout

The effect of sodium-nitrite (NaNO2) and potassium nitrate (KNO3) on the outgrowth and toxigenesis of nonproteolytic Clostridium botulinum in vacuum-packed cold-smoked rainbow trout stored for-six weeks was studied in two inoculation studies at slightly abusive storage temperatures of 4 degrees C and 8 degrees C. The depletion rate of nitrite and the reduction rate of nitrate to nitrite as well as the effect of nitrite and nitrate on the shelf-life of the product during eight weeks' storage period were also determined. The nitrite concentrations were reduced from 166 mg/kg +/- 9 (mean +/- SE), to a final concentration of 34 mg/kg +/- 2 and 11 mg/kg +/- 2, and the nitrate concentrations from 686 mg/kg +/- 67 to 465 mg/kg +/- 140 and 427 mg/kg +/- 33 at 4 degrees C and 8 degrees C respectively. The nitrite depletion rate was more rapid at 8 degrees C; nitrate depletion was not significantly affected by temperature. A considerable amount of nitrite was detected in the nitrate-treated samples in the latter half of the storage period. At 4 degrees C the aerobic plate counts were significantly lower in the samples treated with NaNO2 + NaCl and with KNO3 + NaCl as compared to the NaCl-treated controls, while at 8 degrees C the differences were smaller. The sensorial shelf-life of the product was considerably extended by nitrite and nitrate curing. The nitrite and nitrate concentrations used in the present study did not completely inhibit the toxigenesis of nonproteolytic C. botulinum during the six-week storage period, although the number of toxic samples was considerably reduced by nitrite and nitrate curing.

Liquid chromatographic determination of biogenic amines in dry sausages

A liquid chromatographic method is described for the determination of biogenic amines found in dry sausages: tryptamine, phenylethylamine, putrescine, cadaverine, histamine, serotonin, tyramine, spermidine, and spermine. Amines were extracted with perchloric acid solution and derivatized with dansyl chloride. After derivatization, ammonia was added to remove an interfering peak near cadaverine. Liquid chromatographic separations were performed by using a Spherisorb ODS2 column and an ammonium acetate-acetonitrile gradient elution program. The limits of determination of the individual amines were 1-5 mg/kg. This method is also applicable to detection of amines in other food samples.

Treatment of postpneumonectomy empyema and associated bronchopleural fistula. Experience of 100 consecutive postpneumonectomy patients

Experience in the management of 100 consecutive patients with postpneumonectomy empyema is presented. Open-window thoracostomy was used for treatment of the empyema in all cases. The patients were grouped according to surgical procedure after this treatment. In group 1 the thoracostomy window was left permanently open. In group 2 it was closed, and in group 3 the open pleural cavity was covered with skin, using a pedicle of muscle and skin and free skin transplants. The pectoralis skin pedicle was used to close large bronchopleural fistulas. The results in each group are presented and a staged method, which can be used in all cases of postpneumonectomy empyema, with or without bronchopleural fistula, is described.

Local anaesthesia in carotid surgery. A prospective study of 111 endarterectomies in 100 patients

A prospective study was carried out on 100 patients consecutively undergoing carotid endarterectomy in local anaesthesia, in order to evaluate the usefulness of clinical signs in awake patients for monitoring of cerebral function and to determine the need for internal shunt in carotid surgery. The indications for operations were transient ischemic attacks in 67 patients and major or minor stroke in 24 (16 with persistent neurologic deficit). In nine asymptomatic patients the endarterectomy was prophylactic, following detection of bruit and angiographic stenosis. Bilateral stenosis was present in 47 patients, including 13 with total occlusion of the contralateral vessel, and 60 patients had significant vertebral artery stenosis. The carotid artery was first tentatively occluded and, if this was well tolerated for 5 min, endarterectomy was done without an internal shunt. Neurologic deficit signs during the trial occlusion necessitated such shunt in 16 patients with pressure in the internal carotid stump ranging from 0 to 40 (mean 22.4) mmHg. On the other hand, 11 additional patients with stump pressure less than 35 mmHg tolerated the trial occlusion well, underwent carotid endarterectomy without internal shunt and had no deficit symptoms during or after operation. One patient died postoperatively. Hemiparesis appeared in two more patients, but resolved completely in one and gave only minor sequelae in the other. These complications were related to the preoperative condition (stroke) and the postoperative residual pressure gradient. It is concluded that trial occlusion of the carotid artery and observation of the awake patient provide reliable information on the need for an internal shunt during carotid endarterectomy.

Surgical treatment of nondissecting aneurysms of the descending thoracic aorta

Between 1966 and 1981, 58 patients underwent operation for nondissecting aneurysm of the descending thoracic aorta at the University Central Hospital in Helsinki. The cause of the aneurysm was atherosclerotic in 38 cases. Nine aneurysms were post-traumatic and 11 had developed after correction of aortic coarctation with a Dacron patch. Rupture of the aneurysm with hypotension and haemothorax were present on admission in three patients (5.2%). Six operations were performed without use of shunt or bypass. In the other patients the circulation to the spinal cord and viscera was protected during the aortic resection and reconstruction. Left atrial-to-femoral artery bypass was used in 43 patients, femoral vein-to-femoral artery bypass in five, heparinized TDMAC shunt in three patients and total perfusion in one case. Transient paraparesis and irreversible paraplegia each occurred in one case in which some form of circulatory protection had been used. In the latter patient there was aneurysm rupture and hypotension on admission to hospital, and resection (greater than 10 cm) was done with TDMAC shunt. The patient died postoperatively of pulmonary complications. The total operative mortality was 12.1%. The mortality in the follow-up period (range 1-14 years, mean 5 years) was 13.8%. The conclusion from the study was that, when adequate technique of aneurysm resection is combined with shunt or bypass, an acceptable operative mortality and low incidence of paraplegia are obtainable.

Repair of stricture and fistula of the antethoracic oesophagogastrostoma using a reversed pectoralis skin pedicle flap

A 68-year-old male patient with oesophageal cancer was treated by oesophageal resection and the antethoracic reconstruction was made by using the ventricle. The oesophagogastrostoma developed a necrosis and later a 5 cm stricture and a gastrocutaneous fistula. Both the stricture and the fistula were treated by plastic surgery using a reversed pectoralis skin pedicle flap and free skin graft.

Pedicle thoracoplasty and free skin transplantations in the treatment of open postpneumonectomy cavity after empyema

The method of covering the open postpneumonectomy pleural cavity with skin is used when closure of the thoracostoma is not possible. The operation is performed with pedicles and free skin transplantations. The results in 16 patients treated this way are presented. This method makes it possible to cover the whole open pleural cavity with skin and to reach a satisfactory postpneumonectomy state.

Use of pectoralis skin pedicle flap for closure of large bronchial fistula connected with postpneumonectomy empyema

In 4 patients, the postpneumonectomy empyema was connected with a large bronchopleural fistula. The empyema was in all cases treated by a permanent open window thoracostoma. The fistulae were closed later with pedicle flaps made of the pectoralis muscle and the adjoining skin. In 2 patients the closing of the bronchial fistula was successful, and the treatment of one patient is not completed. In one patient the open pneural cavity was covered completely by skin using an additional pedicle flap and free skin transplantation. The surgical technique of the pedicle flap operation is described and the cases are reported.

Use of omental pedicle for treatment of bronchial fistula after lower lobectomy. Report of two cases

Postoperative bronchopleural fistula in two patients was successfully closed by omental pedicle flap. The primary operation in both cases was left lower lobectomy for bronchiectasis. The technique of the operation is described and the cases are reported.