POULTRY OFFALS RECYCLING PROCESS

This process is patented

Offals including viscera, feathers, heads and feet were minced in a meat type mincer and mixed with molasses in the rate 4:1. pH was adjusted with sulfuric acid as described above. The mixture was dispensed in plastic container 10 kg each.

Figure 2: Flow sheet of slaughter houses wastes biotransformation:

Inoculation and growth parameters
The suitable starter culture was added to 10 kg of the mixture in a plastic container to control the fermentation parameters inluding pH, temperature, agitation and molasses proportions. These parameters are important for a further pilot production and also for the design of a high scale production at the factory. The determination of the suitable conditions for a succeded fermentation was done before any experiment on the biotransformation. This step is the key to an efficient process.
The most suitable pH for the fermentation was between 5.2 and 6. This was adjusted by a 50 % sulfuric acid solution. pH of the product may decrease during the first phase of fermentation due to the growth of L. plantarum to reach a final pH of 4.31. The use of L. plantarum as an acidifying agent in the starter culture may maintain the acidity at a low level in the product to prevent some deteriorations by undesirable microorganims and/or contamination by toxigenic bacteria such as Clostridium or Salmonella. Not only the acid produced by L. plantarum may have a role in preservation but also some antimicrobial metabolites (bacteriocins) can be produced by this species and may contribute to the preservation of the product against pathogens.
The addition of sulfuric acid to the initial mixture may increase the acidity for spoilage microorganims that would induce some undesirable reactions during the begining of fermentation and may prevent some toxins formation. Molasses are added to induce fermentation which may result in lactic acid and some metabolites production. The proportion of 30 % (w/w) results in a best fermentation. This is evaluated by the acid production and growth of lactic acid bacteria.
The temperature was also setted at 26-28 °C. A good fermentation had been observed between 26 and 30°C in a short incubation time. Fermentation by LAB would be done at 30°C.
Chemical and microbiological determinations are carried out on the product during the fermentation and also on the product during storage.
Chemical determinations
The pH was checked by the use of a pH-meter type Crison MicropH 2000. The dry matter was determined by oven drying a weighed amount of the product at 105°C until constant weight. Ash was determined by ignition at 550°C. Fat content was determined on the dry matter by the soxhlet method using hexan as solvent. Total nitrogen (TN) was determined by the Kjeldhal method described by the APHA (1989). The non proteic nitrogen was also determined by the same method on the filtrate after precipitating with a 10 % trichloroacetic acid solution. Total volatile nitrogen (TVN) was measured by the method described by Conway (1947). Trimethylamine (TMA) was determined according to the method described by Murray and Gibson (1972).
Microbiological determinations
Coliforms were determined by pour plating appropriate dilutions on MacConkey agar (Leininger, 1976). The plates were incubated at 37°C. Proteolytic and lipolytic microoganisms were determined according to the methods described by Lee (1976) and Alford (1976) respectively. Clostridium counts were determined by the method described by Faid et al (1990).
Microbiological
The microbial profiles reported in table 3 show the same pattern as for animals wates. Pathogens were eliminated in a short time and less than 1 cfu/g was reached after 10 days. It would be interesting to know about the microbial load of the product obtained by transformation for more elucidation of the safety (pathogens and toxigenic microorganisms). Basically low levels of pathogens may indicate a safe product and consequently the biotransformation process had succed in eliminating or delying undesirable microorganisms.

Table 3: Microbial profiles in the different trials of poultry waste (by-products) transformed by fermentation.

DM: Dry Matter  RS: Reducing Sugar,  Prot = proteins  * calculated as TN x 6.25 in %

SCALE UP OF THE PROCESS
Results obtained in the first program research through the laboratory size experiments were also carried out to define the biotransformation conditions.
Amounts of 100 Kg wastes were fermented in a 200 L inox vessel inoculated with the starter culture and incubated at room temperature (24- 26°C). The assays were carried out in duplicate and the parameters were followed up daily.

Plate count                 10⁶cfu/g
Coliforms                    <1 cfu/g
Clostridium                  <1
Yeasts                        10⁶ cfu/g
Molds                          100 cfu/g
Salmonella                    Not found in 25 g
The obtained product was also analyzed for the final chemical composition:
pH                               4 - 4.8
Total nitrogen               2 - 2.5
Ash                              3 - 4
Dry matter                    36 - 40
Fat                               12 - 18
Fiber                             6 - 8
Carbohydrates              7 - 11.5

Only slight differences were observed in the product relatively to the laboratory assays.

CONCLUSION AND SUGGESTIONS

Up on the foregoing, the biotransformation of wastes by fermentation may constitute a very convenient process for the recycling of the huge amounts of wastes lost every day in the different food treating units (industries, slaughter houses etc..). The process may allow the obtention of products with added values. The innovative research carried out in the present work may lead to the utilization of large amounts of biomass which is discarded.
Moreover, the fermentation by suitable lactic acid bacteria strains may also ensure the safety of the obtained product with regard to hazardous and/or toxigenic microorganisms. It is assumed that lactic acid bacteria have a role in the biopreservation of foodstuffs. Our Research on the recycling of organic wastes is now focused on a low cost-safe-process rather than high cost/high risk process such as drying. The fermentation process by suitable microorganisms would lead to preventing problems related to animal feeding.
Right now the BSE (Bovine Spongiforme Encephalomyelitis) is shaking the world particularly the European countries. This problem seems due to unsuitable feed ingredients. Our research is at a premium for predicting any solution but we are convainced that our research can bring out the solution to prevent a possible cause of the disease through safe ingredients for feed. Imported feed materials from Europe are susceptible to contain proportions of dried animal proteins.

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