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PubMed2003

Health-promoting compounds in broccoli as influenced by refrigerated transport and retail sale period.

Total aliphatic and indole glucosinolates, phenolic compounds (flavonoids and hydroxycinnamoyl derivatives), and vitamin C contents were evaluated in freshly harvested broccoli (Brassica oleracea L., var. italica, cv. Marathon) inflorescences. These were film-wrapped and stored for 7 days at 1 degrees C to simulate a maximum period of commercial transport and distribution. After cold storage, inflorescences were kept for 3 days at 15 degrees C to simulate a retail sale period. For wrapping, low-density polyethylene (LDPE) of 11 microm thickness was used. Gas composition was about 17% O(2) and 2% CO(2) during cold storage and about 16% O(2) and 3-4% CO(2) during shelf life within packages. The predominant glucosinolates were 4-methylsulfinylbutyl-glucosinolate (glucoraphanin), 3-indolylmethyl-glucosinolate (glucobrassicin), and 1-methoxy-3-indolylmethyl-glucosinolate (neoglucobrassicin). The predominant hydroxycinnamoyl derivatives were identified as 1,2,2'-trisinapoylgentiobiose, 1,2-diferuloylgentiobiose, 1,2'-disinapoyl-2-feruloylgentiobiose, and 3-O-caffeoyl-quinic (neochlorogenic acid). Results showed major losses at the end of both periods, in comparison with broccoli at harvest. Thus, the respective losses, at the end of cold storage and retail periods, were 71-80% of total glucosinolates, 62-59% of total flavonoids, 51-44% of sinapic acid derivatives, and 73-74% caffeoyl-quinic acid derivatives. Slight differences in all compound concentrations between storage and retail sale periods were detected. Distribution and retail periods had minimal effects on vitamin C. Weight loss was monitored at the end of both periods.

Ascorbic Acid↗
PubMed2006

Major advances in fresh milk and milk products: fluid milk products and frozen desserts.

Major technological advances in the fluid milk processing industry in the last 25 yr include significant improvements in all the unit operations of separation, standardization, pasteurization, homogenization, and packaging. Many advancements have been directed toward production capacity, automation, and hygienic operation. Extended shelf-life milks are produced by high heat treatment, sometimes coupled with microfiltration or centrifugation. Other nonthermal methods have also been investigated. Flavored milk beverages have increased in popularity, as have milk beverages packaged in single-service, closeable plastic containers. Likewise, the frozen dairy processing industry has seen the development of large-capacity, automated processing equipment for a wide range of products designed to gain market share. Significant advancements in product quality have been made, many of these arising from improved knowledge of the functional properties of ingredients and their impact on structure and texture. Incidents of foodborne disease associated with dairy products continue to occur, necessitating even greater diligence in the control of pathogen transmission. Analytical techniques for the rapid detection of specific types of microorganisms have been developed and greatly improved during this time. Despite tremendous technological advancements for processors and a greater diversity of products for consumers, per capita consumption of fluid milk has declined and consumption of frozen dairy desserts has been steady during this 25-yr period.

Animals↗
PubMed2001

Thermal lethality of Salmonella Senftenberg and Listeria innocua in fully cooked and packaged chicken breast strips via steam pasteurization.

Fully cooked chicken breast strips were surface inoculated to contain 9 log10 (CFU/g) Salmonella Senftenberg or Listeria innocua. The inoculated products were vacuum packaged in 0.2-mm-thick barrier bags (241 by 114 mm), then steam pasteurized at 88 degrees C in a continuous process for 26 to 40 min or in a batch process for 33 to 41 min. After the treatments, the products were analyzed for the survivors of Salmonella or Listeria. The models were developed to correlate the surviving rate of Salmonella and Listeria with cooking time for both continuous and batch processes. A cooking time of 34 min was needed to achieve 7 logs of the reduction in a batch process. To achieve the same log reduction, a longer (6 min) cooking time was needed in a batch process than in a continuous process. The results from this study will be useful for processors to evaluate postcooking treatment procedures for ready-to-eat meat products.

Animals↗
PubMed2006

Influence of antimicrobial compounds and modified atmosphere packaging on radiation sensitivity of Listeria monocytogenes present in ready-to-use carrots (Daucus carota).

Radiosensitization of Listeria monocytogenes was determined in the presence of trans-cinnamaldehyde, Spanish oregano, winter savory, and Chinese cinnamon on peeled minicarrots packed under air or under a modified atmosphere (60% O2, 30% CO2, and 10% N2). Samples were inoculated with L. monocytogenes HPB 2812 serovar 1/2a (106 CFU/g) and were coated separately with each active compound (0.5%, wt/wt) before being packaged under air or the modified atmosphere and irradiated at doses from 0.07 to 2.4 kGy. Results indicated that the bacterium was more resistant to irradiation under air in the absence of active compound. The dose required to reduce L. monocytogenes population by 1 log CFU (D10) was 0.36 kGy for samples packed under air and 0.17 kGy for those packed under the modified atmosphere. The active compounds evaluated in this study had an effect on the radiation sensitivity of L. monocytogenes on carrots. The most efficient compound was trans-cinnamaldehyde, where a mean 3.8-fold increase in relative radiation sensitivity was observed for both atmospheres compared with the control. The addition of winter savory and Chinese cinnamon produced a similar increase in relative radiation sensitivity but only when samples where packed under modified atmosphere conditions.

Anti-Bacterial Agents↗
PubMed1998

Effects of modified atmosphere packaging and preservatives on the shelf-life of high moisture prunes and raisins.

The growth of Aspergillus niger and Zygosaccharomyces rouxii on high moisture prunes and raisins in the presence of preservatives and packed under modified atmospheres was determined. Prunes and raisins adjusted to an aw of 0.84-0.87 in the presence of carbon dioxide atmospheres (40 and 80% CO2) did not support growth of A. niger. However, Z. rouxii spoiled the fruit samples, both in air and under CO2 conditions. Addition of low levels of K-sorbate (186 ppm in prunes and 153 ppm in raisins) or Na-benzoate (176ppm in prunes and 158ppm in raisins) delayed outgrowth of Z. rouxii. The inhibitory effect of preservatives was higher in raisins than in prunes. Modified atmospheres (40% CO2-60% N2 or 80% CO2-20% N2) combined with the addition of 417 and 343 ppm K-sorbate or 383 and 321 ppm Na-benzoate accomplished complete growth inhibition of Z. rouxii and extended the shelf-life of high moisture prunes and raisins at 30 degrees C for at least 6 months.

Air↗
PubMed2001

Influence of packaging on the aroma stability of strawberry syrup during shelf life.

Different types of packaging (glass bottle, PVC, and PET) were compared for the preservation of aroma quality of a strawberry syrup during shelf life. Esters, alcohols, and aldehydes were analyzed by solid-phase micro-extraction (SPME) and solvent extraction. During storage, hydrolysis of esters in acids and alcohols led to a modification of the aroma profile which can be explained by the replacement of "fruity" and "fresh" notes by "dairy note" in the syrup. Aroma compounds that are responsible for fruity notes, such as methyl cinnamate, methyl anthranilate, and methyl dihydrojasmonate, were strongly reduced after 90 days. This could be explained by a selective interaction of these compounds with the polymer matrix (PET or PVC). After 330 days, a later and important decrease of the "fruity notes" occurred in both PETs; so PVC2 and the glass bottle were found to be able to maintain a balanced aroma for long-term storage.

Alcohols↗
PubMed2003

Use of organic acids for the control of Clostridium perfringens in cooked vacuum-packaged restructured roast beef during an alternative cooling procedure.

This study was conducted to determine how well Clostridium perfringens spores germinate and grow in restructured roast beef treated with different commercial organic salts during an alternative chilling procedure. The meat was prepared according to an industrial recipe (10% water, 1.5% sodium chloride, and 0.5% sodium triphosphate). The base meat was treated with sodium citrate at 2 or 4.8% (wt/wt), buffered to a pH of 5.6, 5.0, or 4.4 (six treatments); a 60% (wt/wt) solution of sodium lactate at 2 or 4.8% (wt/wt); sodium acetate at 0.25% (wt/wt); or sodium diacetate at 0.25% (wt/wt). Untreated meat was used as a control. Meat samples were inoculated with a three-strain cocktail of C. perfringens spores (strains ATCC 10388, NCTC 8238, and NCTC 8239). Meat was vacuum packaged in bags and cooked in a stirred water bath to an internal temperature of 75 degrees C for 20 min, and then the bags were cooled from 54.4 to 4.4 degrees C within 18 h. Samples were taken after inoculation, after cooking, and after chilling. Spore and vegetative cell counts were obtained after incubation at 37 degrees C for 8 to 10 h in Fung's Double Tubes containing tryptose sulfite agar without egg yolk enrichment. Cooking was not sufficient to eliminate C. perfringens spores. Over the 18-h cooling period, sodium citrate, sodium lactate, and sodium diacetate reduced the growth of C. perfringens to < 1 log unit, a growth level that meets U.S. Department of Agriculture performance standards. The use of sodium citrate or sodium lactate at a concentration of > or = 2% (wt/wt) inhibited C. perfringens growth over the 18-h cooling period.

Animals↗
PubMed2001

Effect of high oxygen modified atmosphere packaging on microbial growth and sensorial qualities of fresh-cut produce.

The application of High Oxygen Atmospheres (HOA) (i.e. > 70% O2) for packaging ready-to-eat vegetables was evaluated as an alternative technique for low O2 Equilibrium Modified Atmosphere (EMA) packaging (3% O2-5% CO2-balance N2) for respiring products. Comparative experiments between both techniques were performed in-vitro and in-vivo. Typical spoilage causing microorganisms (Pseudomonas fluorescens, Candida lambica), the moulds Botrytis cinerea, Aspergillus flavus and the opportunistic psychrotrophic human pathogenic microorganism associated with refrigerated minimally processed vegetables. Aeromonas caviae (HG4), showed a retarded growth during the conducted in-vitro studies at 4 degrees C in 70%, 80% and 95% O2 as examples of HOA compared to the in-vitro experiments in 5% O2 (as example of EMA packaging) and the effect was more pronounced in 95% O2. The effect of the high O2-concentrations on the human pathogen Listeria monocytogenes resulted in an extended lag phase (95% O2). The plant pathogen Erwinia carotovora was increasingly stimulated by increasing high O2-concentrations. During a storage experiment of three types of ready-to-eat vegetables (mushroom slices, grated celeriac and shredded chicory endive), which are sensitive to enzymatic browning and microbial spoilage, the effect of EMA and HOA (95% O2-5% N2) on their quality and shelf life was compared. High O2 atmospheres were found to be particularly effective in inhibiting enzymatic browning of the tested vegetables. Also, the microbial quality was better as a reduction in yeast growth was observed. The HOA can be applied as an alternative for low O2 modified atmospheres for some specific types of ready-to-eat vegetables, sensitive to enzymatic browning and spoilage by yeasts.

Bacteria↗
PubMed2005

Co-culture experiments demonstrate the usefulness of Lactobacillus sakei 10A to prolong the shelf-life of a model cooked ham.

This study investigated the usefulness of two selected lactic acid bacteria, Lactobacillus sakei subsp. carnosus (10A) and the lactocin S producing L. sakei 148 (LS5), to extend the shelf-life of cooked meat products. The interaction between these potential protective cultures and the spoilage organisms, Leuconostoc mesenteroides (LM4) and Brochothrix thermosphacta (BT1), were examined in co-culture studies on a model cooked ham product at 7 degrees C under vacuum packaged conditions. Furthermore, the influence of the glucose content of the model cooked ham on the interaction phenomena was investigated. When artificially contaminating the model cooked ham with BT1 at 10(2) cfu/g in combination with 10A at 10(5) cfu/g, the growth of BT1 was significantly slower compared to a simultaneous mono-culture experiment. In a similar experiment with LM4, LM4 reached a level of 10(7) cfu/g +/-14 days later when LM4 grew together with 10A compared to its growth in mono-culture. The lactocin S producing LS5 did not demonstrate an inhibitory action towards LM4 or BT1 and is therefore not useful as protective culture on cooked meat products. The glucose level of the model cooked ham had no influence on the observed antagonistic interactions of 10A towards LM4 or BT1, indicating that the action of the biopreservative 10A in cooked meat products is independent of the substrate glucose.

Animals↗
PubMed2005

The effect of electron beam irradiation on the survival of Salmonella enterica serovar typhimurium and psychrotrophic bacteria on raw chicken breasts stored at four degrees celsius for fourteen days.

The effect of high-energy electron beam irradiation on the survival of Salmonella enterica serovar Typhimurium and psychrotrophic bacteria on commercial chicken breast meat was evaluated. Fresh chicken breast meat was purchased from a local poultry processor, inoculated with 8 log10 cfu/mL Salmonella, packaged in Styrofoam trays and over wrapped with a polyvinyl chloride film, and subjected to 0, 1, 2, or 3 kGy of irradiation. The packaged samples were stored at 4 degrees C and analyzed for Salmonella Typhimurium and psychrotrophic organisms at 0, 2, 4, 6, 8, 10, 12, and 14 d of storage. Direct plating and enrichment methods were used for S. Typhimurium analyses. The direct plating method revealed a 4 log reduction in Salmonella for chicken breasts inoculated and treated with 1, 2, or 3 kGy of irradiation. Psychrotrophic counts were conducted at 7 degrees C for 10 d and 25 degrees C for 5 d to determine the effect of incubation methods on the recovery of psychrotrophic organisms. The enrichment method resulted in the repair of injured Salmonella cells and an elevated Salmonella Typhimurium count for all irradiation dosages when compared with data reported for the direct plating method. In general, psychrotrophic counts increased as storage time increased. However, psychrotrophic counts decreased (P < 0.05) as the irradiation dosage increased.

Animals↗
PubMed2000

Shelf-life extension of cod fillets with an acetate buffer spray prior to packaging under modified atmospheres.

Fresh cod fillets (Gadus morhua) were sprayed with a 10% acetate buffer (pH 5.6), packed with an industrial gas-flushing packaging machine under modified atmospheres (50% CO2--45% O2--5% N2, 2 cm3/1 g gas/product ratio) and stored at 7 degrees C for 12 days. Control cod fillets were directly packed and stored under the same conditions. A reduction of the aerobic plate counts was observed immediately after the cod fillets had been sprayed. During storage under modified atmospheres, there was complete inhibition of H2S-producing bacteria and Enterobacteriaceae in the treated cod fillets. Production of total volatile bases and trimethylamine (TMA) was inhibited in treated fillets for 10 days' storage under modified atmospheres. Inhibition of TMA production can be attributed to growth inhibition of H2S-producing bacteria, inhibition of the trimethylamine oxide (TMAO)-dependent metabolism of TMAO-reducing bacteria and the stable pH during storage. The shelf-life, at 7 degrees C, of treated cod fillets, based on cooked flavour score, was almost 12 days, ca 8 days more than shelf-life of the control fillets.

Acetic Acid↗
PubMed2001

Antimicrobial edible packaging based on cellulosic ethers, fatty acids, and nisin incorporation to inhibit Listeria innocua and Staphylococcus aureus.

Edible cellulosic films made with hydroxypropylmethylcellulose (HPMC) have proven to be inadequate moisture barriers. To improve its water vapor barrier properties, different hydrophobic compounds were incorporated into the HPMC matrix. Some fatty acids and derivatives were included into the film-forming solution prior to film formation. Stearic acid was chosen because of its high capacity to reduce significantly the water vapor transmission rate. Antimicrobial activity of edible HPMC film was obtained by the incorporation of nisin into the film-forming solution. Nisin is an antimicrobial peptide effective against gram-positive bacteria. The inhibitory activity of this bacteriocin was tested for inhibition of Listeria innocua and Staphylococcus aureus. The use of stearic acid was observed to reduce the inhibitory activity of active HPMC film against both selected strains. This phenomenon may be explained by electrostatic interactions between the cationic nisin and the anionic stearic acid. Further studies showed that antimicrobial activity of film varied with the nature of the hydrophobic compound incorporated, in decreasing order: film without lipid, methylstearate film, and stearic acid film. This corroborated the idea of electrostatic interactions.

Anti-Bacterial Agents↗
PubMed2005

Inactivation of Escherichia coli O157:H7 in packaged ground beef by allyl isothiocyanate.

Commercial allyl isothiocyanate (AIT) was examined for its ability to reduce numbers of Escherichia coli O157:H7 inoculated in fresh ground beef packaged under nitrogen and stored refrigerated or frozen. A five-strain cocktail of E. coli O157:H7 containing 3 or 6 log10 cfu/g was inoculated into 100 g ground beef and formed into 10x1-cm patties. A 10-cm diameter filter paper disk treated with AIT suspended in sterile corn oil was placed on top of a single patty. One patty and paper disk were placed in a bag of Nylon/EVOH/PE with O2 permeability of 2.3 cm3 m(-2) 24 h atm at 23 degrees C. The bags were back-flushed with 100% nitrogen, heat-sealed and stored at 10, 4 and -18 degrees C for 8, 21 or 35 days, respectively. During storage, the AIT levels in the package headspaces were determined by gas liquid chromatography, and mesophilic bacteria and E. coli O157:H7 were counted. The mesophilic aerobic bacteria in ground beef patties were largely unaffected by the addition of AIT. At an initial population of 3 log10 cfu/g, E. coli O157:H7 was reduced by AIT to undetectable levels after 18 days at 4 degrees C or 10 days at -18 degrees C. In samples inoculated with 6 log10 cfu/g, a >3 log10 reduction of E. coli O157:H7 was observed after 21 days at 4 degrees C, while a 1 log10 reduction was observed after 8 and 35 days at 10 and -18 degrees C, respectively. The final AIT concentrations in the headspaces after storage at 10, 4, and -18 degrees C were 444, 456, and 112 microg/ml at 8, 21, and 35 days, respectively. Results showed that AIT can substantially reduce numbers of E. coli O157:H7 in fresh ground beef during refrigerated or frozen storage.

Animals↗
PubMed2005

In vitro and in situ growth characteristics and behaviour of spoilage organisms associated with anaerobically stored cooked meat products.

AIMS: Understanding spoilage caused by different types of spoilage organisms, associated with vacuum-packaged sliced cooked meat products (CMP). METHODS AND RESULTS: First, strains were characterized in a broth at 7 degrees C under anaerobic conditions to compare their growth rate, acidifying character and metabolite production under conditions simulating refrigerated vacuum-packaged conditions. Brochotrix thermosphacta grew faster than the lactic acid bacteria (LAB). Within the group of the LAB, all strains grew fast except Leuconostoc mesenteroides subsp. dextranicum and Leuconostoc carnosum. Secondly, the organisms were inoculated on a model cooked ham to better understand the relationship between spoilage, microbial growth, pH, metabolite production and accompanying sensory changes. Most rapidly growing strains were Leuc. mesenteroides subsp. mesenteroides followed by B. thermosphacta, while Leuc. mesenteroides subsp. dextranicum and Leuc. carnosum grew very slowly compared with the other LAB. Brochotrix thermosphacta caused sensory deviations at a lower cell number compared with the LAB. The related pH changes, metabolite production and sensory perception are presented. CONCLUSIONS: In this pure culture study, B. thermosphacta and Leuc. mesenteroides subsp. mesenteroides had the highest potential to cause rapid spoilage on CMP. SIGNIFICANCE AND IMPACT OF THE STUDY: A systematic study on the behaviour of spoilage organisms on a model cooked ham to establish the relationship between microbial growth, pH, metabolite formation and organoleptic deviations.

Animals↗
PubMed2004

Stability of salt double-fortified with ferrous fumarate and potassium iodate or iodide under storage and distribution conditions in Kenya.

The stability of table salt double-fortified with iron as ferrous fumarate, and with iodine as potassium iodide or potassium iodate, has been investigated under actual field conditions of storage and distribution in the coastal and highland regions of Kenya. Seven 200-g sample packets of double-fortified salt in sealed polyethylene bags and a similar packet containing a datalogger for monitoring temperature and humidity were packaged with 21 sample bags of salt from another study into a bundle, which then entered the distribution network from a salt manufacturer's facility to the consumer. Iodine retention values of up to 90% or more were obtained during the three-month study. Double-fortified salt was prepared using ferrous fumarate microencapsulated with a combination of binders and coloring agents and coated with soy stearine, in combination with either iodated salt or salt iodized with potassium iodide microencapsulated with dextrin and coated with soy stearine. Most of the ferrous iron was retained, with less than 17% being oxidized to the ferric state. The polyethylene film overwrap of salt packs in the bundles provided significant protection from ambient humidity. Salt double-fortified with iodine and microencapsulated iron ferrous fumarate premix was generally quite stable, because both iodine and ferrous iron were protected during distribution and retail in typical tropical conditions in Kenya's highlands and humid lowlands.

Anemia, Iron-Deficiency↗
PubMed2004

Leuconostoc gelidum and Leuconostoc gasicomitatum strains dominated the lactic acid bacterium population associated with strong slime formation in an acetic-acid herring preserve.

Spoilage characterised by strong slime and gas formation affected some manufacture lots of an acetic-acid Baltic herring (Culpea haerengus membras) preserve after few weeks of storage at 0-6 degrees C. The product consisted of herring filets in acetic acid marinade containing sugar, salt, allspice and carrot slices. Microbiological analyses of the spoiled product showed high lactic acid bacterium (LAB) levels ranging from 4.5x10(8) to 2.4x10(9) CFU/g. Yeasts were not detected in any of the herring samples. Since LAB contaminants are seldom associated with fresh fish, LAB populations associated with marinade ingredients (carrots, allspice) were also analyzed. The highest LAB levels exceeding 10(7) CFU/g were detected in equilibrium modified atmosphere packaged baby carrots whereas the levels detected in the allspice samples did not exceed 4.3x10(5). A total of 176 randomly selected LAB isolates originating from herring, carrot and allspice samples were further identified to species level using a 16 and 23S rRNA gene RFLP (ribotyping) database. Leuconostoc gelidum and Leuconostoc gasicomitatum strains dominated both in the spoiled herring and carrot samples. These species are heterofermentative-producing CO(2) from glucose and they also produce dextran from sucrose. Inoculation of some commercial-herring products with spoilage-associated L. gelidum and L. gasicomitatum strains verified that these strains have the capability of producing slime and gas in herring preserves although slime formation was not as strong as in the original samples. Since L. gelidum and L. gasicomitatum strains were commonly detected in carrots, carrot slices used for the fish marinade were considered to be the probable source of these specific spoilage organisms.

Animals↗
PubMed2001

Effect of various dairy packaging materials on the shelf life and flavor of pasteurized milk.

Milk from three different dairies (each a separate trial: 1, 2, and 3) was standardized to 2% fat and pasteurized at 92.2, 84.0, and 76.4 degrees C (temperatures 1, 2, and 3, respectively) for 25 s and packaged into six different packaging boards, [standard (A) milk boards with standard seam; juice boards with standard (B) and J-bottom (D) seams; barrier boards with standard (C) and J-bottom (E) seams; and foil (F) boards with J-bottom seam], resulting in 18 different treatments. Standard plate count (SPC) was used to test for microbial quality, and taste a panel was employed for flavor acceptability and difference on the milk stored at 6.7 degrees C at 1, 2, 3, and 4 wk. Statistical analysis of taste panel data showed that the flavor of milk samples A2, B2, and D2 deteriorated faster than the blind control (freshly high temperature, short time pasteurized low fat milk processed at 80.6 degrees C for 25 s). The flavor of milk packaged in standard (A) and juice (B and D) boards deteriorated at a faster rate than milk packaged in barrier (C and E) and foil (F) boards. Microbial counts showed that milk samples stored at 6.7 degrees C in trials 2 and 3 produced high SPC at wk 3 (ranges of bacteria in cfu/ml for trial 2: 9.9 x 10(1)-1.8 x 10(6) and trial 3: 2.5 x 10(5)-5.5 x 10(8)). In trial 1, high SPC began at wk 4 (9.9 x 10(1)-5.5 x 10(5) cfu/ml). Milk processed at 76.4 degrees C had the lowest bacterial growth rate, and milk processed at 84.0 degrees C had the highest bacterial growth rate. Different boards had no effects (P > 0.05) on the bacterial growth rates. It appeared that the lower the SPC of the raw milk, the slower the bacterial growth rate after 2 wk of storage. Milk samples stored at 1.7 degrees C maintained low SPC at wk 4, with counts of 0 to 40 cfu/ml for trial 2 and 0 to 200 cfu/ml for trial 3.

Animals↗
PubMed2005

Shelf-life of a chilled precooked chicken product stored in air and under modified atmospheres: microbiological, chemical, sensory attributes.

This study evaluated the effect of modified atmosphere packaging on shelf-life extension of a precooked chicken meat product stored at 4 degrees C using microbiological, physico-chemical and sensory analyses. The following gas mixtures were used: M1: 30%/70% (CO2/N2), M2: 60%/40% (CO2/N2) and M3: 90%/10% (CO2/N2). Identical chicken samples were aerobically packaged and used as control samples. Sampling was carried out at predetermined time intervals namely: 0, 4, 8, 12, 16 and 20 days. Total viable counts (TVC), Lactic acid bacteria (LAB), Brochothrix thermosphacta, pseudomonads, yeasts and molds, and Enterobacteriaceae were monitored. TVC of precooked chicken product reached 7 log cfu/g, after days 12 and 16 of storage (air and M1 samples), respectively. The M2 and M3 gas mixture packaged samples did not reach this value throughout the 20 days storage period under refrigeration. LAB and to a lesser degree B. thermosphacta, constituted part of the natural microflora of precooked chicken samples stored in air and under MAP reaching 7.0-8.1 log cfu/g at the end of storage period. Of the remaining bacterial species monitored, both pseudomonads and yeasts/molds were significantly higher (P<0.05) for chicken samples stored in air than under MAP (M1, M2, M3) throughout the entire storage period under refrigeration. Finally, counts of Enterobacteriaceae were low (<2 log cfu/g) in all chicken samples irrespective of the packaging conditions throughout the entire storage period. Of the chemical indices determined, thiobarbituric (TBA) values in all cases remained low, equal or lower than 3.0 mg malonaldehyde (MA)/kg during the entire storage period. Results of the present work show that the limit of sensory acceptability was only reached for the aerobically stored and M1 gas mixture chicken samples somewhat before days 16 and 20 of storage, respectively. This limit coincided with high TVC and LAB populations (>6.8 log cfu/g), increased lipid oxidation (aerobic storage only) and apparent growth of yeasts/moulds on the surface of chicken samples. The use of MAP as shown in the present study, resulted in an extension of shelf-life of precooked chicken by ca. 4 days (M1 gas mixture), and by more than 6 days (M2 and M3 gas mixtures), respectively. Precooked chicken meat was better preserved under M2 and M3 mixtures maintaining desirable odor/taste attributes even on final day of storage tested.

Animals↗