Potential of the polymer poly-[2-(tert-butylamino) methylstyrene] as antimicrobial packaging material for meat products.

AIMS: The objective of the study was to investigate the antimicrobial potential of a new SAM(®) polymer poly(TBAMS) as packaging material for meat products. METHODS AND RESULTS: The influence of temperature, time and product factors on the antimicrobial activity of poly(TBAMS) against different bacteria was determined using a modified test method based on the Japanese Industrial Standard 2801:2000. Results showed a significant reduction in bacterial counts on poly(TBAMS) compared with the reference material of several meat-specific micro-organisms after 24 h at 7°C. Bacterial counts of Staphylococcus aureus, Listeria monocytogenes, Lactobacillus spp., Brochothrix thermosphacta and Escherichia coli were reduced by >4·0 log10  units. Pseudomonas fluorescens was less sensitive to poly(TBAMS) within 24 h between 2 and 7°C. Prolonging the storage time to 48 h, however, resulted in an increased reduction rate. Furthermore, antimicrobial activity was also observed if meat components in the form of meat extract, meat juice or bovine serum albumin protein were present. Antimicrobial activity was also achieved if inoculated with mixed cultures. CONCLUSIONS: Poly(TBAMS) showed antimicrobial properties under conditions typical for meat supply chains. SIGNIFICANCE AND IMPACT OF THE STUDY: Poly(TBAMS) bears a high potential to increase safety and shelf life of meat products.

Effect of feeding histidine and ß-alanine on carnosine concentration, growth performance, and meat quality of broiler chickens.

The high growth rates of modern broiler breeds increased the risk for novel breast muscle myopathies as serious quality issue, relevant for the industry. In affected muscles, a depletion of the dipeptides carnosine and anserine was reported. Therefore, this study was performed to test whether a supplementation of the precursors histidine and ß-alanine, alone or in combination can increase the dipeptide content in the breast muscle and improve meat quality. Ross 308 broiler chickens were supplemented with 3 different histidine:lysine ratios (0.44, 0.54, 0.64) of standardized ileal digestible amino acids (SID) combined with 0 or 0.5% ß-alanine in total. The birds' performance was recorded at different ages: birds were slaughtered in 2 batches after 33 and 53 d of life. Meat quality was tested at different time points after slaughter on breast fillets stored aerobically. The concentration of the dipeptides and amino acids in blood plasma and muscle tissue was tested postmortem at 35 and 54 d. All performance and meat quality data, as well as peptide and amino acid concentrations, of the 2 × 2 × 3 randomized block design were analyzed separately for the influence of both supplements and for slaughter age. Moreover, the influence of storage time was analyzed separately for meat quality parameters. At both slaughter ages, lesser feed intake (P ≤ 0.005) and breast yield (P ≤ 0.05) were observed in the birds receiving ß-alanine. A greater SID histidine:lysine ratio increased the carnosine concentrations in blood plasma (P < 0.001) and in skeletal muscle (P < 0.001), whereas ß-alanine increased carnosine in plasma at 35 d only (P = 0.004). Anserine was increased in plasma and muscle of older birds (P = 0.003), whereas carnosine was reduced in muscle tissue (P < 0.001). The main impact on meat quality parameters was seen for the age of the birds and storage time of the fillets. In conclusion, the supplementation of histidine increased carnosine in breast muscle but both supplements showed only minor effects on meat quality.

Determination of the shelf life of sliced cooked ham based on the growth of lactic acid bacteria in different steps of the chain.

AIMS: Development of a predictive model for the determination of the shelf life of modified atmosphere-packed (MAP) cooked sliced ham in each step of the cold chain. METHODS AND RESULTS: The growth of lactic acid bacteria (LAB), as well as the development of the total viable count and changes of sensory and pH value parameters in MAP cooked sliced ham, stored under different constant temperature conditions from 2 to 15 degrees C was investigated. As a result of the measurements, the end of the shelf life could be considered as the time when LAB reach more than 7 log(10) CFU g(-1). Different primary and secondary models were tested and analysed to find the best way to calculate the shelf life. For primary modelling, the modified Gompertz Function and the modified Logistic Function were compared. There was no substantial difference between either model. The effect of temperature on the growth rate was modelled by using the Arrhenius and the Square root model, whereas the Arrhenius equation gave a better result. A combination of the primary and secondary model was used for shelf-life prediction under dynamic conditions. This combination showed the best prediction of microbial counts using the modified Logistic model and the Arrhenius equation. CONCLUSIONS: With the developed model, it is possible to predict the shelf life of MAP cooked sliced ham based on the growth of LAB under different temperature conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The developed model can be used to calculate the remaining shelf life in different steps of the chain. Thus, it can deliver an important contribution to improve food quality by optimizing the storage management.

The application of ionizers in domestic refrigerators for reduction in airborne and surface bacteria.

AIM: To investigate the antimicrobial effect of ionization on bacteria in household refrigerators. METHODS AND RESULTS: Ionizer prototypes were tested with respect to their technical requirements and their ability to reduce surface and airborne contamination in household refrigerators. Ion and ozone production of the tested prototypes were measured online by an ion meter and an ozone analyser. The produced negative air ion (NAI) and ozone amounts were between 1.2 and 3.7 x 10(6) NAI cm(-3) and 11 and 19 ppb O(3), respectively. To test the influence of ionization on surface contamination, different materials like plastic, glass and nutrient agar for simulation of food were inoculated with bacterial suspensions. The reduction rate was dependent on surface properties. The effect on airborne bacteria was tested by nebulization of Bacillus subtilis- suspension (containing spores) aerosols in refrigerators with and without an ionizer. A clear reduction in air contamination because of ionization was measured. The antimicrobial effect is dependent on several factors, such as surface construction and airflow patterns within the refrigerator. CONCLUSIONS: Ionization seems to be an effective method for reduction in surface and airborne bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is an initiation for a new consumer tool to decontaminate domestic refrigerators.

Study on the antimicrobial effect of silver-containing inner liners in refrigerators.

AIMS: To investigate the effect of silver-based antimicrobial material incorporated in the inner liners of refrigerators on food safety and quality. METHODS AND RESULTS: In the first stage, the bactericidal effect was tested in the laboratory. Silver-containing samples and control plates were inoculated with different bacterial suspensions and stored at various temperatures. After defined storage periods the bacterial reduction was calculated by comparing viable cell count on reference plates and on silver-containing plates. The reduction caused by the silver-containing material varied between 1.0 and 5.9 log(10) units, depending on bacterial strain, incubation time and temperature. In the second stage, food storage experiments have been carried out. Thus, perishable foods were stored in coated and untreated refrigerators. After certain time periods the products were analysed for their sensorial and microbiological characteristics. A clear drop in viable counts both on the refrigerator wall and on the food was demonstrated using the silver-based antimicrobial material. CONCLUSIONS: Silver prevents refrigerators from being a hot spot for contaminants that could be transferred upon contact with food. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides original results regarding the antimicrobial activity of silver-containing refrigerator surfaces.

Effect of different packaging materials containing poly-[2-(tert-butylamino) methylstyrene] on the growth of spoilage and pathogenic bacteria on fresh meat.

The objective of this study was to investigate the effect of novel antimicrobial packaging materials containing poly-[2-(tertbutylamino) methylstyrene] (poly(TBAMS)) on the growth of typical spoilage and pathogenic bacteria present on meat. The antimicrobial activity of materials containing different poly(TBAMS) concentrations was determined by comparing the bacterial counts on reference and sample materials at different temperatures and times and in the presence of meat components. Storage tests with poultry fillets and veal cutlets were conducted with samples vacuum packaged in the reference foil and foil containing 10% poly(TBAMS). After specific time intervals, typical spoilage microorganisms, total viable count (TVC), sensory changes and pH value were analysed. The results of the different poly(TBAMS) containing packaging materials showed an increase of the antimicrobial activity with an increasing amount of poly(TBAMS) in the base polymer. A high antimicrobial activity against inoculum of spoilage and pathogenic organisms typical for meat products was detected of a multilayer foil containing 10% poly(TBAMS) in the inner layer after 24h at 7°C. Gram positive-bacteria were more sensitive to poly(TBAMS) foil than gram-negative bacteria. In storage tests however, over the entire storage, a significant effect of this poly(TBAMS) foil on microbial growth on chicken breast fillets and veal cutlets could not be identified. Poly(TBAMS) packaging materials showed very good antimicrobial properties against a wide range of bacteria. However, for a significant inhibition of microbial growth on fresh meat, a higher amount of poly(TBAMS) was necessary to prolong the shelf life of meat.

Ainsliaolide D: a new sesquiterpene lactone from Ainsliaea pertyoides.

Ainsliaolide D, a new guaiane-type sesquiterpene lactone, was isolated from the roots of Ainsliaea pertyoides Fr. var. albotomentosa Beauverd. Its structure was determined based on spectral data.