Unlocking Value from Edible By-products

Bovine blood, obtained during the slaughter process, is one of the main contributors to the organic load in slaughterhouse effluents, with high biological oxygen demand (BOD) and nitrogen content. Proper use of blood helps reduce environmental impact and unlocks its highly digestible protein content.

Blood is separated into plasma and corpuscles. After collection, anticoagulants are added, and centrifugation isolates erythrocytes.

Collection Methods
The process starts with bleeding the animal using two knives: one to open the hide and the other to sever major blood vessels at the neck’s base. Blood may be collected in a clean pan or using a vacuum-assisted “vampire” knife, which offers a more hygienic collection method. Once gathered, anticoagulants are sprayed, and the blood is refrigerated for processing.

In the industry, coagulation, centrifugation, and spray drying yield powdered plasma and hemoglobin, useful in various applications including blood sausages.

Anticoagulants used industrially include sodium citrate and food-grade sodium salts for stability. Other additives like EDTA enhance physical properties, while sodium heparin, though effective, is less used due to cost. These are applied in powder form, hydrated, and sprayed during collection.

Depending on processing:

• With anticoagulants and centrifugation → Plasma (contains fibrinogen)
• Coagulated blood → Serum (lacks fibrinogen)

Natural Casings: More than Just a Wrapper

Casings, primarily the submucosal layer of intestines, are sourced from bovine, ovine, porcine, and equine species, with the remaining layers (serosa, muscular, mucosa) removed during processing.

Uses and Characteristics
Casings are not only containers but influence texture, structure, and sensory attributes of the final product. Sheep casings, being translucent and narrow, are used for fine emulsions like cooked sausages. Pork casings suit fresh sausages such as chorizo, while bovine casings, due to larger diameter, are ideal for blood sausages or salami. Pig caecum is used in products like pork cheese, and bovine bladders serve in mortadella production.

Preparation and Preservation
Natural casings are soaked in warm water, sometimes with organic acids. They are salted and bundled, then stored in plastic buckets or barrels. Pre-tubed or pleated casings save time during sausage stuffing.

This entire process defines the casing industry, where most output feeds into sausage production or direct consumption.

Casing Types Include:

• Natural casings
• Reconstituted collagen casings
• Artificial cellulose casings

Mechanically Recovered Meat (MRM): Efficient Resource Use

As demand grows for certain meat cuts, processors are left with bones carrying residual meat and connective tissue. These “meaty bones,” once sold for pet food, are now processed into MRM using specialized equipment.

MRM is ideal for emulsified products like mortadella or Vienna sausages thanks to its texture and emulsifying qualities. It also adds spreadability and smoothness to products like meat pastes and pâtés.

Meat Extract: A Savory Concentrate

Meat extract is produced by concentrating meat broth into a paste, either directly or as a by-product of canned corned beef production. By reducing water content and concentrating salt, it becomes shelf-stable at room temperature.

The endpoint of concentration is determined at 32 degrees Baumé, which also corresponds to around 57.6° Brix. This extract is widely used in the food service industry.

Gelatin: A Hidden Meat Industry Gem

While often associated with candy or dairy products, gelatin is deeply rooted in the meat industry, derived from partial hydrolysis of collagen in animal skin, connective tissue, and bones. It contains nearly all essential amino acids and serves various culinary and industrial applications.

Production Process Includes:

1. Washing raw material
2. Alkaline treatment with calcium hydroxide (7 days to 3 months)
3. Acid wash (HCl or H₂SO₃)
4. Rinse and treatment with aluminum or zinc sulfate for texture and color
5. Sequential extraction at rising temperatures
6. Filtration, usually with diatomaceous earth
7. Deionization using ion-exchange resins
8. Vacuum evaporation
9. Drying on trays and in tunnel dryers
10. Final milling and packaging

Bovine “Primer Juice” (First Tallow Melt): Rendered Fat for Food Use

The first melt of raw bovine or ovine fat—called primer jugo—is obtained by melting fat without separating its natural lipid fractions (oleo-stearin, oleo-margarine). The process involves open-vessel melting at under 80°C or modern alternatives using variable temperature and pressure for equal or superior quality.

This food-grade fat is obtained from:

• Kidney and internal fat
• Fat trimmings from boning operations
• Cover fat and scraps

References: Agroglobal