Microbiological analysis of critical points in the chicken industry

Abstracts

This work is focused on identifying microbial contamination in the scalding asepsis and cooling processes as well as in fresh sausages obtained. Salmonella was identified in two scald water samples but was absent in the water from chiller and in the final product, which might be explained in terms of chlorine addition and temperature reduction. The analysis revealed that MPN of Escherichia coli was in the range of <1-11/mL in the scald water and <1-64/mL in the chiller. Aeromonas sp. count showed 5 to 3.5x10¹ CFU/mL in the scald water and 9 to 3.7x10² CFU/mL in the chiller, probably due to the psycrophile characteristics of Aeromonas and evisceration process. The analysis of fresh sausages chicken revealed a sharp increase in the Aeromonas count (2.5x10³ CFU/g). Results showed the need of including Aeromonas analyzes in microbiological tests of foods.

Aeromonas; bacteria; chicken; microbiology; food quality control

O objetivo deste trabalho foi identificar a contaminação microbiana no processo de escaldagem, assepsia e resfriamento do frango (chiller), e em linguiças de frango produzidas a partir destes. As amostras foram coletadas em um frigorífico de aves, em sete datas e analisadas em triplicata. A presença de Salmonella foi detectada em duas amostras da água de escaldagem não estando mais presente na água do chiller e nem no produto final. Isto se deve à redução de temperatura da água e adição de cloro. O NMP de coliformes fecais variou entre < 1 a 11/ml na água de escaldagem e < 1 a 64/ml na água do chiller, que embora em padrões aceitáveis, mostram tendência de acréscimo no chiller, devido principalmente ao processo de evisceração. As contagens de Aeromonas variaram de 5 a 3,5x10¹UFC/ml na água de escaldagem e 9 a 3,7x10²UFC/ml na água do chiller. Este acréscimo se deve, provavelmente, por Aeromonas ser psicrófila e também devido a retirada das víceras. As análises de linguiça de frango mostraram acréscimo nas contagens de Aeromonas, apresentando até 2,5x10³UFC/g. Esta tendência de aumento de crescimento no produto final, aliado a capacidade de causar infecções de Aeromonas demonstram a necessidade de incluir a análise destas nas avaliações microbiológicas de alimentos.

FOOD SCIENCE AND TECHNOLOGY

Microbiological analysis of critical points in the chicken industry

Rogério Luis Cansian ^* ; Salete Teresa Radeski Floriani; Eunice Valduga

Departamento Ciências Agrárias; URI-Campus de Erechim; Av. 7 de setembro, 1621; [e-mail]; 99700-000; Erechim - RS - Brazil

ABSTRACT

This work is focused on identifying microbial contamination in the scalding asepsis and cooling processes as well as in fresh sausages obtained. Salmonella was identified in two scald water samples but was absent in the water from chiller and in the final product, which might be explained in terms of chlorine addition and temperature reduction. The analysis revealed that MPN of Escherichia coli was in the range of <1-11/mL in the scald water and <1-64/mL in the chiller. Aeromonas sp. count showed 5 to 3.5x10¹ CFU/mL in the scald water and 9 to 3.7x10² CFU/mL in the chiller, probably due to the psycrophile characteristics of Aeromonas and evisceration process. The analysis of fresh sausages chicken revealed a sharp increase in the Aeromonas count (2.5x10³ CFU/g). Results showed the need of including Aeromonas analyzes in microbiological tests of foods.

Keywords:Aeromonas, bacteria, chicken, microbiology, food quality control

RESUMO

O objetivo deste trabalho foi identificar a contaminação microbiana no processo de escaldagem, assepsia e resfriamento do frango (chiller), e em linguiças de frango produzidas a partir destes. As amostras foram coletadas em um frigorífico de aves, em sete datas e analisadas em triplicata. A presença de Salmonella foi detectada em duas amostras da água de escaldagem não estando mais presente na água do chiller e nem no produto final. Isto se deve à redução de temperatura da água e adição de cloro. O NMP de coliformes fecais variou entre < 1 a 11/ml na água de escaldagem e < 1 a 64/ml na água do chiller, que embora em padrões aceitáveis, mostram tendência de acréscimo no chiller, devido principalmente ao processo de evisceração. As contagens de Aeromonas variaram de 5 a 3,5x10¹UFC/ml na água de escaldagem e 9 a 3,7x10²UFC/ml na água do chiller. Este acréscimo se deve, provavelmente, por Aeromonas ser psicrófila e também devido a retirada das víceras. As análises de linguiça de frango mostraram acréscimo nas contagens de Aeromonas, apresentando até 2,5x10³UFC/g. Esta tendência de aumento de crescimento no produto final, aliado a capacidade de causar infecções de Aeromonas demonstram a necessidade de incluir a análise destas nas avaliações microbiológicas de alimentos.

INTRODUCTION

According to the Brazilian Union of Aviculture, the production of chicken in 1998 was around 4.5x10⁶ ton, out of which 3.88x10⁶ ton was used in internal market with a per capita consumption of 24Kg. The chicken industry presents a potential to increase the production in about 5 to 7%. In order to achieve this goal the Brazilian Industry should increase the amount exported to other market like Europe. Due to requirements of external market, it is necessary to improve the inspection, microbiologic control areas and hygiene (Puperi, 1999).

It is well known that most food poisoning is caused by the presence of Staphylococcus aureus, Clostridium perfringens or Salmonella sp. However, 56 to 70% of the suspected or accepted cases are classified as unknown etiology. From the 70's, several research papers have shown that gastroenteritis, peritonitis and endocarditis were due to Aeromonas hydrophila and A. sobria (Janda and Duffey, 1988). As public health regulations are becoming continuously strict and punishment increasingly severely, it seems logical and useful to investigate the conditions of food processing concerning contamination.

The most common microorganisms in chicken meat are mesophile and psycrophile bacteria of the animal and of the environment, which are mainly introduced during processing. In general, A. hydrophila is considered as an aquatic species, which spreads with the irrigation, laundering, feeding, etc.

Nishikawa and Kishi (1988) found a high number of Aeromonas in different food and concluded that the infections caused by this bacterium were mainly related to the contaminated food ingestion and not from water. Involved food in some cases of affection for Aeromonas have disclosed to levels of contamination of the order of 10⁴ the 10⁶ CFU/g (Tood, Hardy, Stringer, and Bartholomew, 1991). Fricker and Tompsett (1989) observed Aeromonas in 79% of different foods.

In fact, there is a lack of information about the occurrence of Aeromonas in food in Brazil, as well as the occurrence of other microorganisms in scalding and chilling water, as coliforms and Salmonella, which are responsible for at least 13% of the gastroenteritis. The aim of this work was identify microbial contamination due to Aeromonas, Escherichia coli, and Salmonella sp. in the scalding asepsis and cooling processes as well as in fresh sausages obtained.

MATERIALS AND METHODS

Samples of the scalding and chilling water were collected in the chicken industry on seven different dates. Three samples of chicken sausage from the lots that had contact with the water under investigation were also collected. The analyses of Aeromonas was conducted by counting in Starch-ampicilin Agar medium (Palumbo, Morgan, and Buchanan, 1985). The sample were serially diluted (10^-1 to 10^-5), according to standard methods of microbiological food analysis (Silva, Junqueira, and Silveira, 1997). All analyses were carried out in triplicates.

The determination of the Most Probable Number (MPN) of fecal coliforms were performed in three series of three pipes, with dilutions of 10⁰, 10^-1 and 10^-2, using lauril broth sulphate triptosis (LST), shining green broth (incubated at 32ºC) and EC broth (incubated at 44.5ºC), for 48 h.

To perform Salmonella analysis, first a pre-enrichment in lactosis broth was carried out at 35ºC for 24 h. Selective enrichment media tetrathionate broth (TT) and selenite-cystine broth (SC) were incubated at 35ºC for 24 h. Then a loopful from each selective enrichment broth culture was streaked in plate with Rambach Agar (Merck) at 35ºC for 24 h.

The measurements of temperature and pH in the scalding and chiller water were carried out for each sample.

RESULTS AND DISCUSSION

The presence of Salmonella sp. was detected in two samples of the scalding water, but not in chilling water and final product. This could probably be due to the reduction of temperature of the water and addition of 5% of chlorine in chiller, eliminating possible existing contaminations of this bacterium.

The Most Probably Number of fecal coliforms (MPN/mL) varied in the range of < 1 to 11 in the scalding water and from < 1 to 46 in the water of chiller (see Fig. 1), which were acceptable values, but showing a clear enhancement in the chiller, mainly due to evisceration step that occur before the cooling (Roitmann, 1988). Temperature of the scalding water varied from 59 to 62ºC, which wont be inhibitory for the majority of the microorganisms, however without capacity of total elimination due to the high microbial load.

Fig. 2 presents the results obtained in the analyses of Aeromonas sp. It was observed that count of Aeromonas sp. varied from 0 to 3.5 x 10¹ CFU/mL (1.54 log CFU/mL) in the scald water and 9 at 4.0x10¹ CFU/mL (0.95 at 1.6 log CFU/mL) in the water of chiller.

This reflected the crossed contamination occurred in the evisceration process before the cooling, an also the fact that Aeromonas be a bacteria psycrophile. Thus, the evisceration process must be carefully accomplished for the control of this bacterium. A possible alteration of pH of the chilling water could be used as control form, since some reports (Knochell, 1990) indicated the inhibition of Aeromonas at 5°C and pH of 5.3 with addition of salt.

Barnhart et al. (1989) showed more contamination in the evisceration process, which the bacterial counts increasing from 28 CFU/mL in laundering fluids of death animal to 580 CFU/mL in laundering fluids after the evisceration process.

The analyses of the chicken sausages showed absence of Salmonella sp. and fecal coliforms with counts up to 110 MPN/g, which was satisfactory conditions for the human consumption (Resolution nº 12 of 2 of January of 2001, of the Agência Nacional de Vigilância Sanitária, ANVISA).

Fig. 3 presents the counts of Aeromonas. When compared with the average counts of Aeromonas in the scalding and chilling water, an increase was observed in sausage, where the count was up to 1.9x10³ CFU/g (3.27 log CFU/g).

Fricker and Tompsett (1989) demonstrated that in a total of 563 samples of sausages, half of the samples presented Aeromonas sp. Amongst the samples, the meats of chicken (79.3%) and visceras: kidneys and liver (84.3%) presented highest incidence of this bacteria. The high frequency of Aeromonas in foods is due to its capacity of growth at low temperature (less than 4 ºC), which makes it to grow under normal conditions of storage of meats, fish, milky vegetables, products, etc (Knochel, 1990; Krovacek, Faris and Mansson, 1991; Beuchat, 1991).

The high temperature of the scald water and low chilling temperature associated with the chlorine use are sufficient for the control of fecal coliforms and Salmonella levels. However, there were probably the cross infections and psycrophile characteristic of Aeromonas hydrophila, which remained viable after the treatments and presented growth in fresh sausages conserved under refrigeration temperature. This fact demonstrated the necessity to include Aeromonas hydrophila in the microbiological food evaluations. Currently Holland and Canada demand its determination in drinking waters and are considered test recommended in the United States and some countries of the Europe, as much for waters as for foods.

Received: April 26, 2004;

Revised: September 03, 2004;

Accepted: March 01, 2005.

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*

Author for correspondence

Publication Dates

• Publication in this collection
  03 Aug 2005
• Date of issue
  May 2005

History

• Reviewed
  03 Sept 2004
• Received
  26 Apr 2004
• Accepted
  01 Mar 2005