Effects of sodium lactate and other additives in a cooked ham product on sensory quality and development of a strain of Lactobacillus curvatus and Listeria monocytogenes.

Cooked cured ham products were produced according to a standard recipe for cooked ham with various levels of sodium lactate, sodium diacetate or buffered sodium citrate. They were compared with a reference ham product with respect to sensory quality and growth of Lactobacillus curvatus and Listeria monocytogenes. For this, a part of the products was sensory analysed directly after preparation. Another part of the cooked ham products was minced and homogeneously inoculated with L. curvatus (10(4)/g) and L. monocytogenes (10(2)/g) and filled in 60-g plastic pouches. After vacuum packaging, the pouches were stored at 4 degrees C for up to 40 days. Between the different ham compositions, only minor differences were found for appearance, internal colour, structure and firmness. The addition of 0.2% Na-diacetate had a negative effect on the odour and taste of the ham product. The addition of 2.5% to 3.3% Na-lactate inhibited the growth of L. curvatus compared to the reference, while 0.1% and 0.2% Na-diacetate did not. L. monocytogenes was best inhibited by the addition of Na-lactate but also by the addition of 0.2% Na-diacetate. On the other hand, the growth of L. monocytogenes was stimulated by the addition of 1% buffered Na-citrate.

[Rapid detection of antimicrobial residues in slaughter animals via ATP determination]. / Snelle aantoning van antimicrobiële residuen in slachtdieren door middel van ATP-bepaling.

A rapid antibiotic test was developed, based on ATP/bioluminescence, to detect antimicrobial residues in slaughter animals as early as possible. Several aspects that influence the assay were studied. For many samples of renal fluid the results of the test agreed very well with the inhibition zones obtained with the new Dutch agar diffusion test. The ATP/antibiotic test offers the possibility of detecting a wide range of antibiotics in renal fluid within 3.5 to 4 hours after receipt of the kidney samples. The detection level is comparable to that of existing agar diffusion tests.

Irradiation of pre-packaged sliced cooked meat products with low and normal sodium content.

Irradiation experiments were carried out with pre-packaged sliced cooked meat products with different initial counts of Enterobacteriaceae and mesophilic aerobic bacteria. In low-sodium meat products Enterobacteriaceae could effectively be inactivated in refrigerated or frozen products by irradiation with a dose of 1 or 2 kGy respectively, provided the number of these bacteria was below 10(3) to 10(4) per g. The low-sodium meat products involved endured above treatment without being seriously affected as to sensory qualities. Shelf-life of salted cooked meat products could be prolonged by irradiating the frozen product. Irradiation with a dose of 2 kGy enabled uncooled storage of the product for a restricted period (5-7 days). Best results were obtained for meat products with a salt content in the brine phase of greater than 4.0% (w/w) and having a good hygienic quality, i.e. an initial bacterial count below 10(4)/g. Packaging in a gas atmosphere (CO2) slightly enhanced protection as compared to vacuum packaging. Off-flavours as a result of irradiation of salted cooked meat products varied from slight to strong and depended on the type of product.

[Water activity as a parameter of keeping quality (author's transl)]. / Wateractiviteitsmetingen en de betekenis van de wateractiviteit als houdbaarheidsparameter van vleesprodukten.

Water activity (aw) is an important property of foods, particularly in relation to the keeping quality. Ever since the Council Directive 77/99/EEC of December 21, 1976 regarding sanitary conditions of meat products for inter-community trade came into operation, water activity was introduced as a parameter in the assessment of meat products. Water activity, i.e. the ratio of the equilibrium vapour pressure of the product to the equilibrium vapour pressure of pure water, can be determined by various methods. Reliable results were obtained using the Sinascope, an electronic hygrometer. Less accurate results were obtained with Lufft's polyamide thread hygrometer. The distinction between perishable and storable meat products, based on pH and aw, is not very rational and lacks a sufficiently scientific foundation.