Hannelore De Maere

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.

Technology-induced selection towards the spoilage microbiota of artisan-type cooked ham packed under modified atmosphere.

The microbiota associated with a highly-perishable Belgian artisan-type cooked ham was analyzed through plating and (GTG)(5)-fingerprinting of isolates throughout its processing chain. The raw tumbled meat was characterized by the presence of a versatile microbiota around 4.8 log(cfu g(-1)), consisting of lactic acid bacteria, staphylococci, Brochothrix thermosphacta, Gram-negative bacteria, and yeasts. Pasteurisation of the ham logs reduced bacterial counts below 2 log(cfu g(-1)) and subsequent manipulations selected for leuconostocs and carnobacteria. Also, B. thermosphacta and several Enterobacteriaceae were found at this stage. During storage in an intermediate high-care area for 2 days, a selection towards certain Enterobacteriaceae (Hafnia alvei, Enterobacter spp., and Pantoea agglomerans) and lactic acid bacteria (mainly vagococci and Streptococcus parauberis) was observed. B. thermosphacta, Leuconostoc carnosum and carnobacteria were also detected, but only after allowing bacterial outgrowth by incubating the meat logs at 7 degrees C for four weeks. After a mild post-pasteurisation process and subsequent handling, incubation of the meat logs at 7 degrees C for four weeks led to outgrowth of Enterobacteriaceae (mainly Enterobacter spp. and Serratia spp.). B. thermosphacta, and lactic acid bacteria (Enterococcus faecalis, Leuc. carnosum, and Carnobacterium maltaromaticum) were also found. After slicing and packaging under modified atmosphere, the microbiota of the refrigerated end-product consisted of leuconostocs, carnobacteria, and B. thermosphacta.

Volatile N-nitrosamines in meat products: Potential precursors, influence of processing, and mitigation strategies

ABSTRACT Meat products can be contaminated with carcinogenic N-nitrosamines, which is ascribed to the reaction between a nitrosating agent, originating from nitrite or smoke, and a secondary amine, derived from protein and lipid degradation. Although in model systems it is demonstrated that many amine containing compounds can be converted to N-nitrosamines, the yield is dependent of reaction conditions (e.g., low pH and high temperature). In this article, the influence of the composition of the meat products (e.g., pH, aw, spices) and processing (e.g., ageing, ripening, fermentation, smoking, heat treatment and storage) on the presence and availability of the amine precursors and the N-nitrosamine formation mechanism is discussed. In addition, this article explores the current N-nitrosamine mitigation strategies in order to obtain healthier and more natural meat products.

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.

DETERMINATION OF HEMIN, PROTOPORPHYRIN IX, AND ZINC(II) PROTOPORPHYRIN IX IN PARMA HAM USING THIN LAYER CHROMATOGRAPHY

An effort was undertaken to investigate a possibility to quantify hemin, protoporphyrin IX (PPIX), and zinc(II) protoporphyrin IX (Zn(II)PPIX) by means of thin-layer chromatography (TLC). All these porphyrins naturally occur in meat and meat products, and they are known for being metabolically interrelated in a not yet fully understood fashion. In view of the results of a current research in meat chemistry, it seems most likely that Zn(II)PPIX is responsible for the red color of Parma ham (a traditional Italian dry ham). This discovery prompted a novel concept that Zn(II)PPIX might replace sodium nitrite and potassium nitrate in the function of the red color-forming pigment, the latter two compounds traditionally used for the same purpose in meat industry, yet known for the formation of the carcinogenic N-nitrosamines as well. In this study, a novel analytical system was proposed for the successful baseline separation of hemin, PPIX, and Zn(II)PPIX, and a possibility was tested of quantifying these three porphyrins in Parma ham. To this effect, the calibration curves were established for the porphyrin standards. Due to the recognized photosensitivity of hemin, PPIX, and Zn(II)PPIX, extraction of these three compounds from Parma ham and the thin-layer chromatographic procedure were carried out in the darkness, although a complete blackout was not always possible. One problem remained unsolved in this study, namely the selection of a proper (preferably a visible light resistant, hence a nonporphyrin) internal standard (IS) for the performance of the recovery procedure for hemin, PPIX, and Zn(II)PPIX contained in the meat matrix. Finally, it was concluded that the elaborated TLC procedure can successfully be implemented to quantification of hemin and PPIX in Parma ham (and in the other meat products as well).

Pervasiveness of Staphylococcus carnosus over Staphylococcus xylosus is affected by the level of acidification within a conventional meat starter culture set-up

Staphylococcus carnosus and Staphylococcus xylosus are commonly used, individually or in combination, within conventional starter cultures for the purposes of colour and flavour development during meat fermentation. Yet, little is known about the relative importance of both species under different processing conditions. The present study aimed at investigating the competitiveness of S. carnosus within a meat starter culture under different acidification profiles. The experimental set-up involved a gradient of decreasing experimental control but increasing realism, ranging from liquid meat fermentation models in a meat simulation medium, over solid mince-based meat fermentation models, to fermented sausage production on pilot-scale level. In general, S. carnosus gained a fitness advantage over S. xylosus in the most acidified variants of each set-up. In contrast, increasing persistence of S. xylosus was seen at the mildest acidification profiles, especially when approximating actual meat fermentation practices. Under such conditions, S. carnosus was reduced to co-prevalence in the mince-based meat fermentation models and was fully outcompeted on pilot-scale level. The latter was even the case when no S. xylosus starter culture was added, whereby S. carnosus was overpowered by staphylococci that originated from the meat background (mostly S. xylosus strains). The results of the present study suggested that conventional starter cultures behave differently when applied in different technological set-ups or using different recipes, with possible repercussions on fermented meat product quality.

In Vitro Zinc Protoporphyrin IX Formation in Different Meat Sources Related to Potentially Important Intrinsic Parameters

For several years, researchers have studied the formation of zinc protoporphyrin IX in meat, as it is considered to be an important natural colouring agent in dry cured or fermented meat products in the absence of nitrite and/ or nitrate. Until now, however, mainly pork meat is used for these investigations. The goal of this research was to relate in vitro zinc protoporphyrin IX and protoporphyrin IX formation in eight meat sources (chicken, turkey, pork, lamb, beef, veal, horse and porcine liver) to eight intrinsic parameters using partial least squares regression (PLS) analysis. Significant differences in pH, initial metmyoglobin formation, metmyoglobin reduction ability, total heme, zinc chelatase activity, and total iron and zinc concentration between meat sources were found. Water activity, however, was not significantly different between meat sources. Liver tissue and horse meat showed the best ability to form zinc protoporphyrin IX. Formation of protoporphyrin IX was limited in all meat sources. PLS analysis revealed that mainly zinc chelatase activity, followed by total heme, total iron and zinc content, were predominant intrinsic parameters to explain variations in zinc protoporphyrin IX formation. These findings could be important for meat industry in order to establish the production of red coloured nitrite-free meat products.

Influence of meat source, pH and production time on zinc protoporphyrin IX formation as natural colouring agent in nitrite-free dry fermented sausages

Nitrite is commonly used in meat products due to its plural technological advantages. However, it is controversial because of its detrimental side effects on health. Within the context of nitrite reduction, zinc protoporphyrin IX (Zn(II)PPIX) formation in meat products as natural red colouring agent has been suggested. This investigation presents the evaluation of naturally occurring pigments, namely Zn(II)PPIX, protoporphyrin IX (PPIX) and heme in nitrite-free dry fermented sausages in function of time, meat source (pork, horsemeat and a combination of both meat sources) and pH condition. In function of time, Zn(II)PPIX and PPIX were formed and heme content decreased. Higher pH conditions promoted Zn(II)PPIX and PPIX formation, whereas the influence of pH on heme was less clear. The use of horsemeat also promoted Zn(II)PPIX formation. Moreover, even similar amounts were formed when it was combined with pork. Product redness, however, could not be related to Zn(II)PPIX formation.