Development of dry-cured sausages using spent-hen meat: manufacturing practices and product physical, chemical and microbiological quality

摘要

Laying hens that complete their egg production cycle in one year constitute one important by-product of the egg industry. They are referred to as spent-egg laying hens, spent layers, or spent hens. Locally, the meat of these spent hens is mainly sold on the fresh market and fetches a significantly lower price than fresh broiler meat. One of the avenues to improve the utiliza­tion of spent-hen meat is to process it into higher value-added products that are palatable and reasonable in cost. The food processing technique that has been chosen is fermentation and drying to produce dry-cured fermented sausages.The research hypotheses were as follows: the meat, skin and abdominal fat of spent-hen meat are technologically suitable for making dry-cured sausages; fermentation/drying can lead to a safe, shelf-stable and quality poultry sausage. Thus, this study was conducted to develop and evaluate a fermented/dried 100-per­cent-poultry sausage made from spent-layer meat and fat.Sausages were prepared using ground meat (breast, thigh and drumstick), skin, and abdominal fat at 10, 15 and 25% levels, salt, sodium nitrite, garlic, and glucose. The mix was inoculated with Lactobacillus plantarum at a rate of ~5.0 log10 colony-forming units (CFU/g). The sausages were stuffed in non-edible cellulose casings. They were dried at 30°C and 85% relative humidity for 15 days, and sampled at 0, 3, 6, 9, 12 and 15 days for analysis of protein and fat contents, color, pH, water activity, total viable count, Salmonella spp., Staphylococcus spp., and L. plantarum counts. Each treatment (25 sausages) was replicated three times.Irrespective of fat levels, pH sharply declined in all batches from an initial value of 6.0–6.3, to 5.3 at day 3, and finally to 4.8–4.9 at day 15 of drying. The average initial moisture content of the sausages was 70% (wet basis). It decreased gradually during the fermentation/drying period to about 51–53% on day 6, and 35% on day 15, irrespective of fat levels. All experimental batches showed similar mass loss over drying time. Mass loss was more pronounced during the first six days (50–55%) and was mainly attributed to moisture loss, as fat drip losses were negligible. Water activity gradually declined from an initial value of 0.97 to 0.71 for the three fat levels. The sausage color changed to reddish brown as from day 3. This translated in decreasing L* (lightness) and positive b* (yellowness) values, and increasing positive a* (redness) values (Figure 1 and Table I).No Salmonella was detected in any samples analyzed. Counts of Staphylococcus spp. were high with 104/g to 108/g at the end of the fermentation/drying period. L. plantarum counts increasedduring the first five days of fermentation from 4.9 to 8.7 log10 CFU/g and remained practically at this level for the rest of the drying period. There was unwanted mould growth on the cel­lulose casings as from day 3. In all cases, the sausages lacked the compactness typical of dry-cured sausages. The meat and fat particles in the final sausages were not uniformly distributed. This may be due to the low melting point of the fat thereby caus­ing smearing of fat particles.Overall, the potential of using spent-layer meat for the manu­facture of dry-fermented sausage was shown to be technologi­cally feasible. However there is a need to optimize the process­ing steps, especially with regard to the starter culture, and the temperature and relative humidity of fermentation/drying, to improve the safety and quality of the sausages.