Predictive model for growth of Clostridium perfringens during cooling of cooked uncured meat and poultry

Comparison of Clostridium perfringens spore germination and outgrowth in cooked uncured products during cooling for different meat species is presented. Cooked, uncured product was inoculated with C. perfringens spores and vacuum packaged. For the isothermal experiments, all samples were incubated in a water bath stabilized at selected temperatures between 10 and 51 °C and sampled periodically. For dynamic experiments, the samples were cooled from 54.4 to 27 °C and subsequently from 27 to 4 °C for different time periods, designated as x and y hours, respectively. The growth models used were based on a model developed by Baranyi and Roberts (1994. A dynamic approach to predicting bacterial growth in food. Int. J. Food Micro. 23, 277-294), which incorporates a constant, referred to as the physiological state constant, q₀. The value of this constant captures the cells’ history before the cooling begins. To estimate specific growth rates, data from isothermal experiments were used, from which a secondary model was developed, based on a form of Ratkowsky’s 4-parameter equation. The estimated growth kinetics associated with pork and chicken were similar, but growth appeared to be slightly greater in beef; for beef, the maximum specific growth rates estimated from the Ratkowsky curve was about 2.7 log₁₀ cfu/h, while for the other two species, chicken and pork, the estimate was about 2.2 log₁₀ cfu/h. Physiological state constants were estimated by minimizing the mean square error of predictions of the log₁₀ of the relative increase versus the corresponding observed quantities for the dynamic experiments: for beef the estimate was 0.007, while those for pork and chicken the estimates were about 0.014 and 0.011, respectively. For a hypothetical 1.5 h cooling from 54 °C to 27° and 5 h to 4 °C, corresponding to USDA-FSIS cooling compliance guidelines, the predicted growth (log₁₀ of the relative increase) for each species was: 1.29 for beef; 1.07 for chicken and 0.95 log₁₀ for pork. However, it was noticed that for pork in particular, the model using the derived q₀ had a tendency to over-predict relative growth when the observed amount of relative growth was small, and under-predict the relative growth when the observed amount of relative growth was large. To provide more fail-safe estimate, rather than using the derived value of q₀, a value of 0.04 is recommended for pork.     

Genotypic difference in postharvest characteristics of hardy kiwifruit (Actinidia arguta and its hybrids), as a new commercial crop: Part II. Consumer acceptability and its main drivers

Actinidia arguta, called also hardy kiwifruit, is an exotic fruit of Actinidia genus which have obtained commercial interest in recent years. Its high frost hardiness, relatively short vegetation period and pro-healthy properties make it very interesting, especially in cold regions. The aim of the presented study was to identify main drivers of postharvest consumer acceptability of A. arguta (and its hybrids with A. purpurea) fruit among its sensory (flavour and texture) attributes and appearance characteristics (size and colour). To achieve that goal nine genotypes were assessed by over 200 consumers during two-year experiment. In order to perform a possibly broad research the chosen genotypes included five of the popular A. arguta cultivars grown around the world, two promising genotypes selected at Warsaw University of Life Sciences (WULS) as well as two hybrids (A. arguta × A. purpurea) from the same source. The study consisted of the consumer assessment of external (appearance) and internal (flavour and texture) fruit liking. The results showed general positive consumer acceptance of hardy kiwifruit with low differentiation of its genotypes. No segment of consumers disliking fruit appearance was found and segments disliking their taste and flavour constituted only about 14% in 2005 and 6% of consumers in 2006, respectively. Study indicated a significant effect of fruit size on consumers as it was highly correlated with the mean liking scores in each of consumer segments. The pink-red skin colour has also large positive impact on consumer's Actinidia choice observed in outstanding acceptance of small ‘D11’ genotype. The most preferable fruit should moreover have sweet taste and odour as these features are significant for most of consumers. Genotypes best meeting consumer preferences were pointed, including A. arguta × A. purpurea, which should obtain special breeders' focus.     

Survival of Campylobacter jejuni on beef and pork under vacuum packaged and retail storage conditions: examination of the role of natural meat microflora on C. jejuni survival

The ability of Campylobacter jejuni ATCC 11168 to survive on beef and pork stored under chilled, vacuum packaged and retail display conditions were examined. In addition, the effect of natural microflora on commercial beef and pork on the survival of C. jejuni under these storage conditions was examined. When sterile cores of beef and pork were inoculated with ∼10⁵ to 10⁶ cfu cm⁻²C. jejuni, and were stored under aerobic or vacuum packaged conditions at −1.5 or 4 °C, its numbers dropped significantly and C. jejuni could not be enumerated by direct plating after 21 d of the 6 wks study. In contrast, survival of C. jejuni on commercial vacuum packaged beef and pork was significantly enhanced, resulting in only 1 log cfu cm⁻² reduction at the end of 6 wks. During 7 d of display in a retail case, numbers of C. jejuni dropped quickly, but could be enumerated by direct plating even after the 7 d. The presence of high numbers of inoculated C. jejuni on beef and pork had no significant effect on the natural microflora numbers compared to uninoculated controls when the meat was stored either in vacuum or in a retail display case. These results show that natural microflora on vacuum packaged meat afford enhanced survival of C. jejuni present on the surfaces of both beef and pork when stored at refrigeration temperatures. Hence, strict hygienic practices or the implementation of decontamination technologies are recommended to ensure safety of meat with respect to this pathogen.     

IRISH AND EUROPEAN CONSUMER VIEWS ON FOOD SAFETY

Results from two consumer surveys are presented. In the first, a EU FAIR (European Union Food, Agriculture and Industrial Research Programme), supported project, three-thousand consumers (500 in each of six countries, Germany, Italy, Britain, Spain, Sweden and Ireland) were surveyed in March 1997 on their attitudes to the quality and safety of three meats, beef, pork and chicken. This paper deals with the safety aspects of the survey. Many consumers in all six countries said they were eating less beef and more chicken. Overall, the Spanish and Irish appeared to be the most concerned about the safety of meat, the British were somewhat less concerned. While many were confident that the food in shops is safe, there was a sizeable minority who believed the contrary. When looking for information on the safety of meat, butchers, whether independent or in supermarkets, are the group most trusted by consumers. In terms of consumer concerns, about 60 percent of beef consumers were very concerned about hormones, BSE (Bovine Spongiform encephalopathy), antibiotics and bacteria. Pork consumers had similar levels of concern as beef consumers about bacteria, antibiotics and hormones. For chicken there was a higher level of concern about bacteria (Salmonella) (68% were very concerned) and similar levels of concern to pork and beef for the other issues. Generally, fat was the issue of least concern for all three meats. Freshness was considered to be relatively the most helpful of 7 factors used for assessing safety of meat. The country of origin and what the animal was fed were also considered to be relatively helpful. Factors considered to be relatively less helpful were price and the name of the producer. In the second study, over 1200 pre-leaving certificate Irish school children participated in autumn 1996 in a national survey assessing young people's attitudes to meat. Half of the respondents agreed with the view that eating beef means increasing the risk of getting CJD (Creutzfeldt-Jakob Disease). Those who agreed were more likely to be less frequent eaters of beef and to have reduced their meat consumption in the post-BSE period. It was found also that females were more likely to eat less meat than males and to have reduced beef consumption. The implications of some of the findings of these two surveys are discussed.     

Species diversity and metabolic impact of the microbiota are low in spontaneously acidified Belgian sausages with an added starter culture of Staphylococcus carnosus

Quality of fermented sausages is affected by acidifying lactic acid bacteria (LAB) and colour- and flavour-promoting coagulase-negative staphylococci (CNS), whether or not used as starter culture. Artisan fermented sausages are often perceived as superior to industrial variants, partially because of the specific microbiota due to spontaneous acidification, which may be considered as an artisan characteristic. Therefore, two kinds of spontaneously acidified Belgian sausages were prepared (Belgian-type salami and Boulogne sausage), but with addition of a Staphylococcus carnosus culture. The Belgian-type salami was made from pork and beef, whereas the Boulogne sausage contained pork and horse meat. In all cases, Lactobacillus sakei was the dominant LAB species present on the raw materials and during fermentation, whereas enterococci remained present in the background. Enterobacteriaceae vanished after fermentation. The CNS species diversity on the raw materials was large and differed between the pork, beef, and horse meat. Nevertheless, this species diversity was annihilated during fermentation by the added S. carnosus culture. The volatiles fraction was mainly composed of aldehydes that originated from lipid oxidation and spices-derived compounds. Aromatic compounds that are typically associated to CNS activity, such as end-products from the metabolism of branched-chain amino acids, were not present in the Belgian-type salami and only marginally present in the Boulogne sausage. In conclusion, spontaneous acidification of Belgian-type fermented sausages leads to dominance of L. sakei and is no guarantee for bacterial contribution to the aroma profile when S. carnosus is added as a starter culture.     

Perceived relevance and foods with health-related claims

Although consumer perception of the health claims and nutrition information has been studied widely there is relatively little understanding about the motivational factors underpinning claim perception. The objective of this study is to investigate how levels of perceived relevance influence consumers’ responses to health claims that either promise to reduce a targeted disease risk or improve well-being in comparison to other types of health-related messages, and how attitudes towards nutritionally healthy eating, functional food and previous experience relating to products with health claims affect the consumers’ perceptions of nutrition and health claims. The data (N = 2385) were collected by paper and pencil surveys in Finland, the UK, Germany and Italy on a target group of consumers over 35 year old, solely or jointly responsible for the family’s food shopping. The results showed that relevance has a strong influence on perceptions of personal benefit and willingness to buy products with health claims. However the impact of relevance is much stronger when the health risks are relevant to self than when it is relevant to those close to oneself, especially when the claim promises a targeted risk reduction with detailed information about function and health outcome. Previous experience with products with health claims and interest in nutritionally healthy eating promoted the utility of all claims, regardless of whether they were health or nutrition claims. However, to be influenced by health claims consumers also need to have a positive attitude towards functional food products.     

The influence of product attributes, consumer attitudes and characteristics on the acceptance of: (1) Novel bread and milk, and dietary supplements and (2) fish and novel meats as dietary vehicles of long chain omega 3 fatty acids

Two conjoint studies were undertaken in the USA on relative preferences for sources and food vehicles for long chain omega-3 fatty acids (LCO3FA). Study 1 (n = 202) investigated consumer acceptance of the source of LCO3FA (fish oil, algal oil and novel oilseed) in the most popular, well established vehicle foods (bread, milk and supplements). Study 2 (n = 211) investigated consumer acceptance of the source of LCO3FA (fishmeal, novel oilseed and fish oil) used to enrich the diet of animals for meat production (beef, chicken, pork and fish). Product concepts were varied by base product (vehicle); source of LCO3FA; information source; health claim and additional cost.These samples of US consumers reported preferences for novel (genetically modified, GM) oilseed incorporated into enriched foods (i.e., bread, milk and supplements) and also for meats above fish and fish oil as sources of LCO3FA and vehicles for consumption. Overall conjoint analysis revealed a general positive relative utility (worth or value) for novel oilseeds which were related to neutral or positive attitudes towards GM.Generally, the acceptance of enriched foods was dependent on the type of the base food and the cost of fish, with bread preferred over milk and supplements. Similarly, for meat, base (vehicle) product was significantly the most important driver of preference, with about 80% of the sample expressing highest preferences for chicken, fed oilseed (as a source of LCO3FA). However, cost was not an important driver of acceptance of meat alternatives.Further, knowledge that the novel oilseed was derived from a GM source did not impact on the acceptance of food alternatives. Thus, incorporating GM oilseeds rich in LCO3FA into animal feed, particularly for chicken and beef, and for enriching bread was found to be acceptable amongst the majority. These two studies suggest the existence of a potential demand for novel ‘non-fish’ source of LCO3FA, providing potential health benefits not currently realised.     

A comparison of the physicochemical and sensory characteristics of alheira samples from different-sized producers

Alheira is a traditional Portuguese meat product made from boiled meat, usually pork and/or poultry, and bread. The physicochemical and sensory properties of alheira were analyzed to determine the relationships between them and to evaluate how they are affected by the product’s origin i.e. if is produced on a small or industrial scale. The most important variables used to characterize alheira are: color, visual evaluation of the amount of meat and bread, paprika aroma, clamminess and fibrousness, water activity, moisture, fat, carbohydrate content, hardness and color parameters (L^∗, a^∗,  and b^∗). Principal component analysis demonstrated that drying has a major effect on these characteristics, as it plays a part in the product’s physical make-up. Using these parameters it was possible to ascertain that industrial products enjoyed higher levels of consumer acceptability, given that they contain a higher proportion of meat and undergo a shorter drying process.     

Labelling information demanded by European consumers and relationships with purchasing motives, quality and safety of meat

Meat labelling can be an important way of informing the consumer on the quality attributes of meat. However, the type of information consumers demand is not well known and there is a lack of consumer-oriented information. Thus, meat labelling requires special attention. The objectives of this paper were: to identify the type of information that is most demanded by European consumers on beef and lamb labelling; to analyse the relationships between the importance of informational cues and other aspects concerning consumer attitudes towards meat consumption and meat quality, and socio-demographic characteristics; and to identify groups of consumers according to their labelling preferences. The information cues considered most important related to the deadline for meat consumption and the origin of meat. Other important cues were nutritional information, maturation time, name of cut and, especially for beef consumers, information on the system of production and on the traceability and the quality control of the meat. Some groups or segments of consumers were identified that had significant differences in relation to the type of information demanded, purchasing motives, quality preferences, sources of information on quality they trusted most and socio-economic features. They could be briefly profiled as: 'quality/safety orientated'; 'traditional'; 'quality unconcerned/ convenience-driven' and 'origin motivated' consumers.     

One technology does not fit all: Profiling consumers of tender and tenderised beef steaks

New production technologies can help the beef sector to improve eating quality, in particular the tenderness, of low-value meat cuts. This paper aims at profiling potential consumers for unprocessed tenderloin M. Psoas major, muscle profiled M. Infraspinatus and marinated by injection M. Semitendinosus in Belgium (n = 108) and Norway (n = 110). Consumers' hedonic expectations for the three beef cuts, along with their general attitudes towards beef and food technology, were collected in central location tests. Results show that tenderloin triggers the highest hedonic expectations and best appeals to consumers profiled with high beef involvement in both countries. Consumers' expectations for steaks from novel technologies vary with consumers' attitudes towards beef, food technology and food risks and their country of residence, resulting in three additional consumer profiles. Furthermore, general attitudinal profiles of beef consumers also differ between the two countries. The results are useful for the positioning of novel beef products within the two national markets.     

Socio-economic factors affecting consumer behaviour for United States and Spanish beef under different information scenarios

This study analyzes the results of taste tests on US and Spanish-produced beef conducted with a Spanish consumer panel. The objective is to explore variation in the sensory and market evaluations of the beef products in relation to a series of socio-economic factors. The tasters are assigned to one of three different experimental scenarios based on the amount of product information disclosed. The results show that consumers’ evaluations differ according to the degree of product information provided and that the socio-economic factors with most effect on consumers’ evaluations were gender, age, and education level. Thus, the higher educated, higher income consumers reveal a preference for intrinsic attributes and for the US beef, as long as they are unaware of its foreign origin.     

Identification of hare meat by a species-specific marker of mitochondrial origin

Meat species identification in food has gained increasing interest in recent years due to public health, economic and legal concerns. Following the consumer trend towards high quality products, game meat has earned much attention. The aim of the present work was to develop a DNA-based technique able to identify hare meat. Mitochondrial cytochrome b gene was used to design species-specific primers for hare detection. The new primers proved to be highly specific to Lepus species, allowing the detection of 0.01% of hare meat in pork meat by polymerase chain reaction (PCR). A real-time PCR assay with the new intercalating EvaGreen dye was further proposed as a specific and fast tool for hare identification with increased sensitivity (1 pg) compared to end-point PCR (10 pg). It can be concluded that the proposed new primers can be used by both species-specific end-point PCR or real-time PCR to accurately authenticate hare meat.     

Prevalence of extended-spectrum β-lactamase-producing Enterobacteriaceae in meat products sold in Navarra,Spain

Patterns of resistance in β-lactamase-producing Enterobacteriaceae family were investigated in isolates from 141 meat products (beef, poultry and pork) purchased in Spain. The strains that grow in ChromID ESBL agar plates were confirmed using the paired disk diffusion method. Resistance to amoxicillin/clavulanic acid, ceftazidime, ceftriaxone, aztreonam, cefpodoxime, gentamicin, doxycycline, cotrimoxazol, norfloxacin, piperacillin/tazobactam, fosfomycin and cefoxitin were tested following CLSI recommendations. Minimum inhibitory concentrations were determined by the MicroScan® NM37 panel and β-lactamase genes were detected using multiplex PCR and sequencing. Results show poultry as the meat product having the highest prevalence (84%), with Escherichia coli being the predominant bacteria (71.3%). Predominant β-lactamase types were CTX-M (37.8%), followed by CTX-M + TEM combination (20.7%), TEM (17%), SHV (12.2%), TEM + SHV combination (10.9%) and OXA (1.2%). 93.9% of the strains were resistant to one or more β-lactam antibiotics. Results indicate a widespread distribution of ESBL-producing Enterobacteriaceae in meat products, with a high rate of β-lactam resistance and a low rate of AmpC cephalosporinase-producing strains.     

Physicochemical properties and tenderness of meat samples using proteolytic extract from Calotropis procera latex

This study was conducted in order to tenderise muscle foods (pork, beef and chicken) by using crude enzyme extract from Calotropis procera latex. Chunks of knuckle muscle from pork and beef as well as of breast muscle from chicken were marinated with distiled water (control) and 0.05%, 0.1%, 0.2%, 0.3% and 0.5% (w/w) of crude enzyme extract powder for 60 min at 4 °C. The marinated samples were then subjected to various physical and chemical property determinations. A decrease in moisture content was observed when the crude enzyme extract was added. Firmness and toughness of the muscle samples significantly decreased with the increased addition of crude enzyme extract (p < 0.05). The water holding capacity and cooking yield of the treated samples showed no significant difference throughout the crude enzyme extract addition (p > 0.05). Crude enzyme extract had no effect on the pH of the pork sample, but it slightly increased the pH in the beef and chicken. An increase in protein solubility and TCA-soluble peptides content was observed in all of the treated samples. The electrophoresis pattern of the muscle treated samples also revealed extensive proteolysis occurring in each muscle type. From the results, it is determined that latex from Calotropis procera can be used as an alternative source of proteolytic enzymes for the effective tenderising of meat.     

Production systems – An example from Brazil

Important information about the Brazilian agribusiness, population and economy are presented in this paper, as well as details of beef production, market, industry and production system, to inform people involved in meat industry about details on demography, production, economy and production systems of a country that is the largest player in beef exports in the world and that uses, mostly, Bos indicus based bovine population, reared under pasture conditions, for meat production purposes. Herd size, genetic evaluation programs, quantity of beef produced and market is informed, with figures about the global and major players’ production. Some discussion related to environmental concerns, methane emission and carbon fixation is also presented, as well as meat quality. Meat quality of fed animals is also compared with beef from animals that are raised in pasture conditions.     

Salmonella surveillance and control at post-harvest in the Belgian pork meat chain

Salmonella remains the primary cause of reported bacterial food borne disease outbreaks in Belgium. Pork and pork products are recognized as one of the major sources of human salmonellosis. In contrast with the primary production and slaughterhouse phases of the pork meat production chain, only a few studies have focussed on the post-harvest stages. The goal of this study was to evaluate Salmonella and Escherichia coli contamination at the Belgian post-harvest stages. E. coli counts were estimated in order to evaluate the levels of faecal contamination. The results of bacteriological analysis from seven cutting plants, four meat-mincing plants and the four largest Belgian retailers were collected from official and self-monitoring controls. The prevalence of Salmonella in the cutting plants and meat-mincing plants ranged from 0% to 50%. The most frequently isolated serotype was Salmonella typhimurium. The prevalence in minced meat at retail level ranged from 0.3% to 4.3%. The levels of Salmonella contamination estimated from semi-quantitative analysis of data relating to carcasses, cuts of meat and minced meat were equal to −3.40 ± 2.04 log CFU/cm², −2.64 ± 1.76 log CFU/g and −2.35 ± 1.09 log CFU/g, respectively. The E. coli results in meat cuts and minced meat ranged from 0.21 ± 0.50 to 1.23 ± 0.89 log CFU/g and from 1.33 ± 0.58 to 2.78 ± 0.43 log CFU/g, respectively. The results showed that faecal contamination still needs to be reduced, especially in specific individual plants.     

European consumers' acceptance of beef processing technologies: A focus group study

The use of new technologies in beef production chains may affect consumers' opinion of meat products. A qualitative study was performed to investigate consumers' acceptance of seven beef processing technologies: marinating by injection aiming for increased 1) healthiness; 2) safety; and 3) eating quality; 4) marinating by submerging aiming for increased eating quality; 5) nutritional enhancement and restructuring through enzyme binding; 6) shock wave treatment and 7) thermal processing. Participants' attitudes towards beef, their innovativeness and risk aversion were also assessed. In total, 65 adults (19–60 years old) participated in eight focus groups in Spain, France, Germany and the UK. Results suggested a relationship between acceptance of new beef products, technology familiarity and perceived risks related to its application. Excessive manipulation and fear of moving away from ‘natural’ beef were considered negative outcomes of technological innovations. Beef processing technologies were predominantly perceived as valuable options for convenience shoppers and less demanding consumers. Overall, respondents supported the development of ‘non-invasive’ technologies that were able to provide more healthiness and better eating quality. Excessive intervention in meat production chains was severely criticized and participants expressed their longing to keep beef processing ‘simple and natural’.

Industrial relevance

The aim of the present study is to investigate European consumers' acceptance or rejection of beef processing technologies, exploring their attitudes, risk aversion and innovativeness. An inventory of acceptable beef processes and products is provided as a tool to guide process and product innovation in the beef chain, contributing to increase the competitiveness of beef. Of special interest is the understanding of the acceptance of novel beef processing technologies, since it can satisfy modern consumer demands for convenience, health, eating quality and food safety, adding value to beef products.     

Satureja horvatii essential oil: In vitro antimicrobial and antiradical properties and in situ control of Listeria monocytogenes in pork meat

The dominant compounds in Satureja horvatii oil were p-cymene (33.14%), thymol (26.11%) and thymol methyl ether (15.08%). The minimum inhibitory concentration (MIC) varied from 0.03 to 0.57 mg/mL for bacteria, and from 0.56 to 2.23 mg/mL for yeast strains, while minimum bactericidal/yeast-cidal concentration (MBC/MYC) varied from 0.07 to 1.15 mg/mL and 1.11 to 5.57 mg/mL for bacteria and yeasts, respectively. The antiradical potential of the essential oil was evaluated using hydroxyl radical (•OH) generated in Fenton reaction. The meat preserving potential of essential oil from Satureja horvatii was investigated against L. monocytogenes. Essential oil successfully inhibited development of L. monocytogenes in pork meat. Sensorial evaluation on flavor and color of meat was performed. The color and flavor of meat treated with essential oil improved after 4 days of storage. S. horvatii essential oil can act as a potent inhibitor of food spoiling microorganisms, in meat products and also can be a useful source of natural antioxidants.     

Danish initiatives to improve the safety of meat products

During the last two decades the major food safety problems in Denmark, as determined by the number of human patients, has been associated with bacterial infections stemming from meat products and eggs. The bacterial pathogens causing the majority of human infections has been Salmonella and Campylobacter, and to a lesser extent Yersinia, Escherichiacoli O157 and Listeria. Danish initiatives to improve the safety of meat products have focused on the entire production chain from the farm to the consumer, with a special emphasis on the pre-harvest stage of production. The control of bacterial pathogens which are resistant to antibiotics has been a new area of attention in the recent decade, and recently, the increasing globalization of the domestic food supply has called for a complete rethinking of the national food safety strategies. The implementations of a “case-by-case” risk assessment system, as well as increased international collaboration on surveillance, are both elements in this new strategy.