MEAT FERMENTATION ( CURING )

1. MEAT FERMENTATION ( CURING )

2. The actual number and types of products are many and depended largely on geography. In warmer areas, the Middle East and around the Mediterranean, spices were often added, and a drying step was common. In colder, Northern areas, where sausage technology is more recent, spices were rarely added, and instead products were usually smoked or sometimes cooked following fermentation.

3. the preservation of fermented meats serves as a perfect example of what food scientists now refer to as the hurdle or barrier concept of food preservation. Preservation is achieved by a combination of processes, such that fermentation is combined with drying, salting, smoking, cooking, and antimicrobial chemicals to ensure safety and to enhance preservation

4. Today the variety of fermented meat products ~ cheese in the world. In Spain : 50 different types of fermented sausages in Germany: more than 350. this variation is due to -the meat source (i.e., beef, pork, goat, sheep, etc.) -the cut of meat -the amount and coarseness of the fat -the casing material used The level of dryness, smoking or mold growth are important factors and form the basis of fermented meats classification

5. Meat Composition Fresh meat is a nutrient-rich medium and is, in fact, one of the best for supporting growth of microorganisms. Skeletal bovine muscle contains: -nearly 20% of high quality protein -About 2% to 3% lipid -small amount of carbohydrate -non-protein nitrogen -and inorganic material. -about 75% is water( aw is nearly 0.99) -pH of the fresh tissue, before rigor, is 6.8 to 7.0, but decreases to about 5.6 to 5.8 following rigor, due to post-mortem glycolysis by endogenous enzymes present within muscle cells.

6. Fermentation Principles In contrast to the lactic acid fermentation in milk, the meat fermentation has been, until recently, considerably less well studied and understood. the use of pure, defined starter cultures in the fermented meats industry is a relatively recent development (begun in the 1950s and ‘60s). Before backslopping were common.

7. Backslopping works for several reasons: -selects for those bacteria that are well suited for growth in the sausage environment. -the bacterial population is heterogenous consisting of multiple species and strains. (If one strain were to suddenly die remaining strains could complete the fermentation.) -effective due to large size of the inoculum (usually around 5%, can be as high as 20% of the total mass to overwhelm the background flora)

8. drawbacks of backslopping: -inconsistent quality -fermentations can be unreliable and difficult to control. -can’t meet tight production schedules -microbiologically risky, may permit growth of Staphylococcus aureus, Listeria monocytogenes, C. botulinum, or other pathogens of public health significance

9. If a cooking step is not included, fermentation is the main barrier against pathogens. fermentation: is not too long ….a slow or failed fermentation may not be discovered right away …. permitting growth of pathogenic bacteria. subsequent acid production (or even a heating step) may not be sufficient to inactivate these high level of pathogens.

10. Sausages grouped under four major category -Fermented sausages or sausages dried in air ( can be consumed without cooking, normal sausages) Ham ( from pork )---- equivalently pastırma ……prepared from uncooked materials -Boiled sausages…..prepared from uncooked materials but during processing either boiled in water or treated with steam …frankfurter, salami ( in Turkish sosis, salam..) -cooked sausages -fried sausages

11. Semidry sausages(in USA) : rapid fermentation at an elevated temp, without or with a short period of drying followed by cooking (at 60–68°C). Traditional Mediterranean:slow ripening process, development of moulds and yeasts on the surface. No smoking. Shelf-life: due to drying and reduced aw. In northern and central Europe, fermentation+smoking, of yeasts and moulds are prevented, and the drying is shorter. summer sausage, fermented at 38 °C and no drying.

12. Microbiology of Fermentation meat is naturally contaminated with Lactobacillus, Carnobacterium, Micrococcus, Staphylococcus, Pseudomonas, Acinetobacter, Enterococcus, Arthrobacter, Corynebacterium, Brochothrix and Listeria, and also Enterobacteriaceae, yeasts and moulds.

13. Spoilage Bacteria Gram-negative aerobicspoilage mos,disappear through the fermentation period. Pathogenic Bacteria Clostridium, Staphylococcus aureus, Listeria and Enterobacteriaceae (including Salmonella):easily controlled if good practice is applied.

14. Starter Cultures for Fermented Sausages The LAB : Lactobacillus sakei, L.curvatus, (18-25C)(slow fermentation to provide sufficient time for nitrate-reduction and color and flavor development )L. plantarum, Pediococcus acidilactici and P. pentosaceus. ( 35-40 C) ( for fast, consistent large scale productions)

15. acetic acid:undesirable in fermented sausage because it imparts a sour, vinegar-like flavor

16. the inclusion ofMicrococcaceaein meat starter cultures is optional.( don’t produce acid ) included in starter cultures to convert nitrate to nitrite by enzyme nitrate reductase. ( they help form flavor and enhance color ) mesophilic : 18°C to 25°C. If ferment at higher temp (e.g., 32°C to 40°C), the rapid acid development would inhibit growth of the micrococci

17. functions of meat starter cultures (1) produce L acid and lower the pH; (2) produce desirable flavors; (3) out-compete spoilage and pathogenic mos; (4) lower the Eh, ( inhibits Salmonella, S. Aureus); (5) Micrococcaceae :flavor and color via reduction of nitrate.

18. Bacteriocins: proteinaceous substances with bactericidal activity Produced by: P. acidilactici, L. plantarum, and L. sakei. Bacteriocins provides one more barrier and an extra margin of safety.

19. How to include bacteriocin? - including bacteriocin-producing strains in a starter culture -a pure bacteriocin can either be added directly to the sausage batter or applied to the surface in the form of a dip or spray. - incorporate bacteriocins into packaging films.

20. - nisin: only bacteriocin recognized as safe”(GRAS) a dehydrated or paste form which are commercially available as shelf-life extenders

21. Raw Materials and Additives only five ingredients are essential: meat, sugar, salt, - culture, curing agent.

22. Meat the main ingredient. Beef fat susceptible to oxidation rxns, rancid flavors) Chilled meats (frozen meat tempered to −4 °C) and frozen porcine fats::mixed 2:1.( pH should be 5.8 or lowerto prevent undesired bacteria)

23. Salt ( essential ingredient in all types) Functions: -extracting and solubilizing the muscle proteins -provides flavor -controlling the microflora. (2–4%) containing 0.4–0.6% sodium nitrite (NaNO2)

24. Sugar fresh meat contains little fermentable sugar, and addition of sugar is necessary. glucose (0.5–1%) can be added to impart flavour and moderate the harshness of salt Addition of reducing sugars (e.g. glucose solids, dextrose) to the brine: helps in browning reactions (bacon.)

25. Seasonings (spices) pepper, cloves (karanfil), allspice (yenibahar)and cinnamon ,Garlic and onion . aqueous smoke solution:to provide a smoked flavour. spices and herbs: act as antioxidants by reducing the rate of oxidative rancidity

26. Sodium Nitrite/ Sodium Nitrate sodium nitrite (or nitrate): colour and flavour oxidative stability: by preventing lipid oxidation

27. addition is highly regulated due to the possible risk of formation of N-nitrosamines. In Canada, 200 ppm (20 g per 100 kg; United States, in all products except bacon: 200 ppm;

28. additional additives for Northern type sausages phosphates (0.5%) Tripolyphosphates, hexametaphosphates, most widely used, to increase the water-holding capacity of cured meat products. Alkaline phosphates: increase the pH, solubilizing muscle proteins to impart the water-retention action . improve retention of the cured meat colour

29. glucono-δ-lactone (GdL, 0.5%): fast chemical acidulation (GdL): for products with a short shelf-life ( many strains of LAB ferment this compound to lactic and acetic acid where acetic acid interferes with reactions leading to and stabilizing desired sensory properties.) soya isolataccelerate fermentation.

30. Culture Most commercial cultures Frozen cultures: (-The cans should be thawed in cold water prior to use. Lyophilized cultures: - less common - usually more expensive

31. Sausage Making

32. Comminution( grinding) or Chopping Raw materials and additives, including microbial starters: under vacuum, in a mincer or ‘cutter’. knives that rotate rapidly (1–3 × 103 r.p.m.), producing a batter in a bowl that rotates slowly (10–20 r.p.m.) relative speeds, knives and bowl, determine the fat particle size and are optimized to produce a batter within less than 5 minutes at temperatures ≤2 °C,

33. a meat grinder Bowl chopper

34. Stuffing the batter is immediately stuffed under vacuum into natural, semisynthetic (collagen) or synthetic casings that are permeable to water and air, and both ends are clipped. The sausage diameter (e.g. 2–15 cm)

36. SAUSAGE CASINGS Animal Casings the oldest of packaging matls for sausage: the animal casing. the collagen is hardened and rendered less soluble by the application of salt. Initially, as the collagen is exposed to heat and drying, it becomes less permeable to moisture.

37. the initial step: drying to develop the appropriate smoke permeability. The sheep casings are the smallest in diameter and are also the most tender.

38. Manufactured Collagen Casings manufactured casing: collagen. collagen casing: Alginate Casing, Cellulose Casings from high-grade wood pulp, Plastic casings, polyethylene or a polyamide (Nylon). The collagen is solubilized and later extruded and hardened

39. Ripening (Fermentation + others ) hung in racks, put into natural or, mostly, air-conditioned fermentation chambers at highRH. ripening in two consecutive stages: fermentation -Northern (20–24 °C/50–90%/2-3 days) - Mediterranean (5–24 °C/10–90%/100 h) - in USA( 37-40 C, 12-18 h)

40. the pH at the end of fermentation should be less than 5.1, …. provide a reasonable protective barrier against most foodborne pathogens.

41. Cooking, drying, and smoking • In the USA: often cooked after fermentation( any pork containing sausage must be cooked to destroy Trichinae cause the disease Trichinella in humans.)(usually 60°C to 62°C) • in Europe : raw sausages are the norm, and post-fermentation heating steps are rarely applied. • Cooking inactivates the culture and stops the fermentation, but it also kills pathogenic microorganisms

42. B) transfer to another chamber, drying for development of sensory characteristics. If the RH is too low, temp too high, drying will initially be rapid. …….. the surface will become dehydrated and form a hard, water-impermeable skin. This phenomenon, called case hardening,

43. Smoking Northern type: oak wood (300–600 °C) to minimize the production of polycyclic hydrocarbons. Smoke: antimicrobial,antioxidant effects, generates specific flavour and colour components.

44. Sausage Metabolism and Safety the starting material,meat,is raw and cannot be heat-processed to inactivate spoilage or other undesirable microorganisms

45. To lower redox potential ( omission of oxygen by chopping under vacuum, addition of ascorbic acid or ascorbate). This inhibits aerobic bacteria and improves the bactericidal effectiveness of nitrite, a major hurdle. Drying, addition of salt ( reduction in the water activity,

46. The use of starters that are amino acid decarboxylase-deficient and contain antioxidant enzymes undesirable moulds on the sausage exterior is prevented by pretreatment of the casing with potassium sorbate or pimaricine solutions.

47. Rings of sucuk (spicy sausage) hang outside the butcher shop.

48. Flow diagram for manufacture of fermented sausage

50. Typical Defects and Their Causes surface is blurred: tempof the fat was not low enough during comminution, blending and stuffing. sausage is deformed: too rapid drying, case-hardening, smeared fat under the casing.