Cheese whey is a by-product of the cheesemaking process. It is the yellowish liquid that separates from the curds during the making of most cheeses. After milk is coagulated to form curds (the solids), the remaining liquid is known as whey.
Whey contains about 50% of the total solids from the original milk. This includes proteins, minerals, vitamins, and lactose sugar. It also retains about 70-90% of the milk minerals and contains most water-soluble vitamins from the milk.
Composition of Whey
The exact composition of whey depends on factors like the type of milk used and variety of cheese produced. But in general, whey contains:
- Water: Around 93-95%
- Lactose: Approx. 70% of milk sugar, 4.5-5% whey solids
- Proteins: 20% of milk protein, 0.6-0.8% whey solids
- Minerals: 70-90% of milk minerals, 0.5-0.7% whey solids
- Fat: Traces
- Lactic acid: Present in acid whey
Whey proteins mainly consist of β-lactoglobulin and α-lactalbumin. The total protein also includes small amounts rennet and lipase enzymes used during cheesemaking.
Types of Cheese Whey
There are two main types of whey produced during cheesemaking:
Sweet Whey
Sweet whey, also called rennet whey, comes from cheeses produced using rennet enzymes for coagulation. This includes popular cheeses like cheddar, Swiss, Parmesan etc.
Sweet whey has a pH of 6.2-6.4 and contains little mineral salts. It does not have lactic acid.
Acid Whey
Acid whey is produced when making cheeses coagulated using acids like vinegar or lemon juice instead of rennet. Examples include cottage cheese and cream cheese.
Acid whey has lower pH of 5.0-4.6 due to the presence of lactic acid. It also contains higher mineral salts like calcium lactate.
The type of cheese impacts the exact composition and properties of the expelled whey.
Production and Problems of Whey
During cheesemaking, about 9-14 pounds of whey is produced per pound of cheese curd formed. So cheese factories generate huge quantities of whey daily.
The global annual cheese production is around 24 million tons which leads to almost 22 million tons of cheese whey.
This excess whey was earlier regarded as a troublesome waste product by dairies. When disposed untreated, it causes serious environmental issues:
- Has high biological oxygen demand (BOD) - can deplete oxygen in water bodies leading to aquatic life destruction
- Contains high concentration of organic matter like lactose sugars - promotes uncontrolled microbial growth impacting ecosystems
Due to its detrimental environmental effects if discharged improperly, managing surplus whey in eco-friendly ways is vital for cheese producers.
Key Takeaway: Cheese plants produce very large quantities of whey, needing sustainable solutions for handling it.
Whey Processing Solutions
Earlier whey was carelessly disposed as effluent or used in low value applications like animal feed. But with increasing awareness of its rich composition and pollution potential, cheese companies now use improved techniques:
Whey Concentration
Partial water removal by evaporation or membrane filtration (ultrafiltration, reverse osmosis) to concentrate whey proteins and lactose. Concentrates can be further processed into whey powder, whey protein isolate etc.
Reduces product volumes, enabling economical storage and transport.
Whey Fractionation
Separation into individual protein and lactose fractions using filtration processes. These purified components have wider applications in food and pharmaceutical sectors.
Conversion Into Value-Added Products
Fermentation to produce vitamins, acids, gases, ethanol etc. Or base material for single cell proteins. Enables full utilization of all nutrients in a sustainable manner.
Applications of Whey
Thanks to recognition of its nutritional value, rich composition and improved processing methods, surplus whey today finds uses in diverse products:
Food Industry
Whey powder, whey protein concentrates, lactose products are used in -
- Bakery - breads, biscuits
- Confectionery - chocolate, candy
- Dairy - yogurt, ice cream, processed cheese
- Beverages - smoothies, health drinks
- Infant formulas
- Animal feed
Whey permeate remaining after protein removal is used to form -
- Probiotic drinks
- Bioethanol
- Organic acids by fermentation
Non-Food Applications
- Pharma products - lactose is an inert carrier and coating agent
- Cosmetics - moisturizing and film-forming properties
- Whey protein hydrolysates in creams, lotions
- Biodegradable plastics
- Biogas production by anaerobic digestion
Instead of being a polluting waste, cheese whey is now processed into a wide range products owing to its rich nutritional profile and techno-functional properties.
Whey Cheese
Whey drained off after coagulating milk into cheese also contains around 50% of milk solids itself. This residual protein and fat can be recovered to make whey cheese, also termed as albumin or ricotta cheese.
Whey cheese utilizes the solids left behind in expended whey after cheese production.
Production
Whey cheese is produced by 2 methods:
1. Coagulating Proteins
Heating whey to 195°F or above causes the soluble whey proteins to denature and precipitate out from the whey. The coagulated proteins are then collected by filtering and pressed into whey cheese.
Acid like vinegar or lemon juice can also be added to aid protein coagulation.
2. Concentrating Whey
In this method, whey is simply boiled down to evaporate most of the water content. This concentrates the residual lactose and milk solids present into whey cheese.
Characteristics
- Soft, crumbly texture
- White to pale yellow color
- Mild flavor, sweet taste due to lactose
- Lower yield than cheese curd
Whey cheese has good nutritive value owing to high protein content. But it tends to be deficient in calcium and some essential amino acids compared to regular cheese.
Common examples include ricotta, brocciu, urda, mysost.
Uses
Ricotta and whey cheese are popular ingredients in:
- Lasagna, ravioli, pizza and other Italian dishes
- Cheesecakes, pastry fillings
- Dips, salads, dressings
- Salty or sweet snacks
Their light texture and mild taste allows utilizing whey cheese in many preparations, both in savory and sweet recipes.
Environmental Impact
Historically, disposing large volumes of whey from cheese factories has been a major ecological concern:
- Organic matter present depletes oxygen levels in water bodies via microbial action
- Nutrients like lactose, proteins in whey promote algal blooms and uncontrolled growth altering aquatic ecosystems
- Changes pH, salinity impacting flora and fauna
- Milk solids increase turbidity, hindering sunlight penetration
Studies by Purser and Baker in the 1990s showed that 1 liter of whey has a similar pollution potential as 3 liters of domestic sewage.
Hence, uncontrolled whey disposal into water streams severely impacts the natural biological cycles. Sustainable whey management practices are vital for environmental preservation as well as utilizing its nutritional richness.
Converting Whey into Beverages
To cater to growing consumer demand for healthy, functional drinks, whey is now used to produce various novel beverages:
Whey Protein Beverages
- Clear protein waters, shakes
- Meal replacements
- Sports and post workout drinks
Fortified with whey protein isolates for extra nutrition.
Fermented Probiotic Beverages
Whey permeate, deproteinized whey etc. fermented using cultures like kefir grains. May include fruit juice or yogurt cultures addition.
Whey-based smoothies
Whey protein powders provide high quality nutrition and desired texture when blended with fruits, veggies, nuts etc.
Whey lemonades or sodas
Sweet whey or whey powder used with added fruit flavors to form refreshing carbonated drinks.
Alcoholic Beverages
- Whey wine - wine fermented using microbes on whey as substrates instead of sugars from fruits
- Whey beer - malted whey, water and hops brewed into beers
FAQs
What are the different types of whey?
The two main varieties are sweet whey produced using rennet and acid whey formed via acid coagulation of milk. Their composition varies based on cheese type.
Why was whey considered an environmental issue earlier?
Whey has high BOD causing oxygen depletion in water bodies. And unchecked microbial growth on whey damages aquatic ecosystems.
What are the components in whey used for making products?
Mainly whey protein isolates, concentrates, hydrolysates, lactose, lactic acid and mineral salts.
How is whey converted into whey cheese?
Either by heat coagulation of residual proteins or boiling down to concentrate overall solids. Common examples are ricotta, mysost, brocciu etc.
What kind of whey beverages are produced nowadays?
Whey protein shakes, fermented probiotic drinks, smoothies, lemonades, alcoholic wines and beer using whey.
Conclusion
Cheese whey was initially regarded as a challenging waste by-product of the dairy industry.
But ongoing research and improved processing methods have now established whey as a nutritionally rich co-product for manufacturing various food ingredients, products and beverages.
Whey constituents like proteins, lactose and minerals are also increasingly finding novel non-food applications.
Additionally, processing surplus whey in eco-friendly ways rather than disposing as effluent has helped resolve its pollution issues.