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. carrion's 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

Species pervasiveness within the group of coagulase-negative staphylococci associated with meat fermentation is modulated by pH

During spontaneous meat fermentations, Staphylococcus equorum, Staphylococcus saprophyticus, and Staphylococcus xylosus are generally the most prevailing species within the communities of coagulase-negative staphylococci (CNS). There is an interest to introduce CNS isolates from artisan-style spontaneous meat fermentations as starter cultures in more industrialized processes, as to confer additional quality benefits. However, staphylococcal competitiveness within the meat matrix is affected by the processing conditions, which vary considerably among product types. A major factor of variability relates to the intensity of acidification, driven by the concentration of added carbohydrates. The effect of pH on CNS prevalence was studied in both a mince-based meat fermentation model and in fermented sausages produced on pilot scale. Roughly, from all experiments combined, it appeared that a pH of 5.3 corresponded with a breakpoint for CNS selection. Above this value, a general prevalence by S. xylosus was found, even overruling the addition of starter cultures consisting of S. equorum and S. saprophyticus strains. At pH values below 5.3, S. xylosus was also accompanied by S. equorum (following a mild pH drop) and S. saprophyticus (following a stronger pH drop). Still, addition of starter cultures affected the volatile profile compared to the control batch, even if those starter cultures were not able to dominate during the ripening process. This study nonetheless provides a warning for an overly confident use of specific CNS species as starter cultures, especially when in a given processing context the prevailing conditions do not allow superior growth compared to the CNS from the background microbiota

Zinc protoporphyrin IX formation in relation to the colouring of nitrite-free dry fermented sausages.

The colour of fresh meat is mainly determined by myoglobin, which is found in large quantities in mammalian muscles (≈ 30% of the total muscle proteins). Myoglobin has a globular structure and consists of one chain of 153 amino acids enclosing a non-protein heme group. This heme group, an iron-containing protoporphyrin IX, is the active center of myoglobin and directly responsible for the colour of meat. Traditionally, sodium nitrite and/ or potassium nitrate are used for the colouring of meat products. Nitric oxide (NO), formed after the reduction of the added nitrite and/ or nitrate, is bound to heme. This resulting nitrosyl myoglobin gives raw meat products their characteristic red colour. Consumers are increasingly aware of the impact and the importance of a healthy lifestyle and therefore have a growing interest in healthy food. Because of this increasing awareness, the use of "chemical" additives is becoming less obvious. Especially sodium nitrite (E250) and potassium nitrate (E252) are controversial. Although nitrite also increases the microbial shelf-life and safety, this additive is nevertheless considered to be undesirable as it is involved in the formation of carcinogenic N-nitrosamines. Therefore, strict regulations were formulated to limit the use of nitrite and nitrate. Under current European legislation, the maximum allowed amount of sodium nitrite for all meat products is only 150 mg / kg [Directive 2006/52 / EC]. For a long time nitrosyl myoglobin was regarded as the only molecule that could give meat products their attractive red colour. In contrast to this generally accepted idea, however, it was established in 2004 that the red colour of Parma ham, a traditional Italian dried ham, was not due to the formation of nitrosyl myoglobin but zinc protoporphyrin IX was identified as the colour-forming pigment. Similar to heme, zinkprotopofyrine IX has a protoporphyrin IX structure, but instead of iron zinc is complexed in the pyrrole ring. Until now, the formation mechanism of zinc protoporphyrin IX has not yet been clarified sufficiently. More knowledge about this red pigment, however, would be interesting to replace sodium nitrite or potassium nitrate in other meat products with regard to the colour formation, such as, for example, in dry fermented sausages. The purpose of this doctoral study is to assess whether zinc protoporphyrin IX can be formed during the production of nitrite-free dry fermented sausage and what effect it has on colour formation. Additionally, investigation will be done on the influence of product and process factors on formation of this natural pigment, in order to obtain an attractive colour in meat products without any addition of additives.status: publishe

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

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.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=bfsn20status: publishe

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.status: publishe

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

International audienceNitrite 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

pH Dependence of (zinc) protoporphyrin IX formation in nitrite-free dry fermented sausages

edition: 2status: publishe

Determination of selected protoporphyrins in Parma ham with use of 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin as a surrogate standard in the recovery study

A high-performance liquid chromatographic analysis for the determination of hemin, protoporphyrin IX (PPIX), and zinc(II)protoporphyrin IX (Zn(II)PPIX) in Parma ham was developed. The detection was done by means of a universal DAD-detector, whereby quantification of the three naturally occurring protoporphyrins was carried out at λ = 414 nm, i.e., very close to the respective maxima of their Soret bands. The extraction thereof from the meat matrix was done by a mixture of acetone and chloroacetic acid (100 mL + 0.2 g). Usage of 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin (THPP) as a surrogate standard and its detection fixed at λ = 444 nm, allowed to obtain accurate (ca. 96%) recovery results. Established concentrations of hemin, Zn(II)PPIX, and PPIX in the Parma ham samples were 15.97, 19.96 and 1.52 µg g-1, respectively.status: publishe

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 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.publisher: Elsevier articletitle: Formation of naturally occurring pigments during the production of nitrite-free dry fermented sausages journaltitle: Meat Science articlelink: http://dx.doi.org/10.1016/j.meatsci.2015.11.024 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Assessment of the N-nitrosopiperidine formation risk from piperine and piperidine contained in spices used as meat product additives

The N-nitrosopiperidine (NPIP) formation in blends of spices and nitrite curing salt was investigated in relation with the piperine and piperidine contents in spices. Firstly, two analytical methods were developed. Piperine was extracted with dichloromethane by means of accelerated solvent extraction (ASE) and determined by high-performance liquid chromatography (HPLC)–diode array detector (λ� =� 343� nm). A selective hydroextraction of piperidine using ASE and its quantification by HPLC–ELSD was applied. Both methods were sufficiently sensitive and accurate (limit of detection, limit of quantification, and recovery: 0.28, 0.84� μg, and 98.9� ±� 2.6� % for piperine, and 5.76, 17.45� μg, and 95.9� ±� 2.9� % for piperidine, respectively). Secondly, both compounds were quantified in commercial samples (black and white pepper, paprika, chili pepper, allspice, and nutmeg). The maximum amount of piperine (21.12� mg� g⁻¹) was found in pepper, while the other spices contained only traces. Piperidine was detected mainly in the pepper samples, whereby the highest concentration was found in the white pepper extract (11.42� mg� g⁻¹). Thirdly, during the storage of spices blended with nitrite curing salt, the NPIP content was determined, using a gas chromatograph coupled with a thermal energy analyzer. Against our expectations, no NPIP formation was observed in the curing mixture which contained white pepper extract. This result remains in contrast with the white pepper mixture, in which the NPIP content significantly increased from not detected to 9.80� ±� 0.41� ng� g⁻¹ after the 2� months storage period. In conclusion, high amounts of piperine or piperidine in spices do not systematically result in the formation of NPIP, when blended with nitrite curing salt.status: publishe