Lore Eveline Marieke Dewulf

The occurrence of N-nitrosamines, residual nitrite and biogenic amines in commercial dry fermented sausages and evaluation of their occasional relation.

Regarding food borne intoxications, the accumulation of biogenic amines must be avoided in all kinds of food products. Moreover, biogenic amines can function as precursors for the formation of carcinogenic N-nitrosamines when nitrite is present. To estimate the food safety of the dry fermented sausages available on the Belgian market, a screening of the residual sodium nitrite and nitrate contents, biogenic amines and volatile N-nitrosamine concentrations was performed on 101 samples. The median concentrations of residual NaNO2 and NaNO3 were each individually lower than 20mg/kg. In general, the biogenic amine accumulation remained low at the end of shelf life. Only in one product the amounts of cadaverine and putrescine reached intoxicating levels. Concerning the occurrence of N-nitrosamines, only N-nitrosopiperidine and N-nitrosomorpholine were detected in a high number of samples (resp. 22% and 28%). No correlation between the presence of N-nitrosamines and the biogenic amines content was observed. Although the N-nitrosamines could not been linked to specific product categories, the occurrence of N-nitrosopiperidine could probably be attributed to the use of pepper.

Interactions between bacterial isolates from modified-atmosphere-packaged artisan-type cooked ham in view of the development of a bioprotective culture

Growth and metabolite production of three dominant bacterial isolates (Carnobacterium divergens 3M14, Leuconostoc carnosum 3M42, and Brochothrix thermosphacta RMS6) from modified-atmosphere-packaged (MAP), artisan-type cooked ham were assessed for their interactions in view of the development of a bioprotective culture. During monoculture experiments in cooked ham simulation medium, Leuc. carnosum 3M42 converted the available glucose into lactic acid and ethanol, whereas the two other strains produced additional metabolites such as acetic acid and 3-methyl-1-butanol. When grown in co-culture, Leuc. carnosum 3M42 suppressed the growth and metabolism of B. thermosphacta RMS6. In contrast, a co-culture of the latter bacterium with C. divergens 3M14 led to a variety of spoilage-related metabolic compounds. Subsequently, experiments with a commercial cooked ham product indicated that Leuc. carnosum 3M42 dominated the meat matrix and improved acceptability of the product over time, hence acting as a bioprotective culture for MAP, artisan-type cooked ham.

Formation of naturally occurring pigments during the production of nitrite-free dry fermented sausages.

This study investigates the potential of producing red coloured dry fermented sausages without the addition of nitrite and/or nitrate. Therefore, the formation of zinc protoporphyrin IX (Zn(II)PPIX) as naturally occurring pigment, and the interrelated protoporphyrin IX (PPIX) and heme content were evaluated during nitrite-free dry fermented sausage production at different pH conditions. Zn(II)PPIX was only able to form in dry fermented sausages at pH conditions higher than approximately 4.9. Additionally, the presence of Zn(II)PPIX increased drastically at the later phase of the production process (up to day 177), confirming that in addition to pH, time is also a crucial factor for its formation. Similarly, PPIX also accumulated in the meat products at increased pH conditions and production times. In contrast, a breakdown of heme was observed. This breakdown was more gradual and independent of pH and showed no clear relationship with the formed amounts of Zn(II)PPIX and PPIX. A statistically significant relationship between Zn(II)PPIX formation and product redness was established.

APPLICATION OF ACCELERATED SOLVENT EXTRACTION (ASE) AND THIN LAYER CHROMATOGRAPHY (TLC) TO DETERMINATION OF PIPERINE IN COMMERCIAL SAMPLES OF PEPPER (PIPER NIGRUM L.)

In this preliminary study, an attempt was made to develop a simple yet reliable overall approach to quantification of piperine in pepper (Piper nigrum L.), and also in the other piperine-containing spice compositions. Such an approach can prove useful for rapid screening of the commercially traded pepper (and other spices) in a pulverized form, with piperine as a single adulteration marker. The main features of this approach consist in a rapid (ca. 40 min) and exhaustive (as proved in a recovery experiment) extraction of plant material with use of Accelerated Solvent Extraction (ASE), followed by an easy thin-layer chromatographic quantification of piperine in the obtained extracts. Within the framework of this approach, dichloromethane (DCM) was selected as an extracting agent and the extraction temperature was fixed at 70°C. With use of the piperine standard, the calibration curve was developed and applicability of the proposed approach was tested upon the commercial samples of white and black pepper in a pulverized and peppercorn form. The piperine levels obtained with the commercial pepper samples remained in agreement with the data available from the literature. Moreover, the assumed quantification approach correctly differentiates between the lower piperine levels in an unripe (black) pepper and the higher ones in a ripe (white) pepper, and also between the lower piperine levels extractable from the whole peppercorn and the higher ones extractable from the ground pepper. Now on the basis of this preliminary study, a completely validated method of quantifying piperine in botanical matter with use of the proposed approach can be elaborated.