Packaging of Dairy Products
Fluid Milk – Pasteurized Milk
Liquid Milk for consumption MUST be pasteurized and before it is packed
Generally only 90-99% of microbes in milk are destroyed by pasteurization
Fluid Milk – Pasteurized MilkPHTC
(Post Heat Treatment Contamination)A cold-tolerant Gram-negative spoilage bacteria affects the shelf-life of
commercial pasteurized milk at refrigerated storage temperatures.These bacteria are completely inactivated by pasteurization
BUT with inefficient sanitation of milk contact surfaces and contamination from dairy plant atmosphere – can be regularly found in pasteurized milk
Fluid Milk – Pasteurized Milk
Shelf-life of Pasteurized Milk – depends on the activity of heat-resistant organisms
Typical Shelf-life 8-10 days at
Realistic Shelf-life18-20 days at
Fluid Milk – Pasteurized: Temperature
ThermizationThis is to delay spoilage of milk during storage
before pasteurizationUsually for cheese production
Its insufficient to destroy bacterial pathogens but will destroy bacteria (psychotrophs)
Fluid Milk – Pasteurized: Temperature
PasteurizationLTLT method or Holder Process
HTST method
After being subjected to heat the milk is cooled immediately
Fluid Milk – Pasteurized: Temperature
Ultrapasteurization(Extended Shelf-life or Superpasteurized)
Destroy all pathogenic organisms
“Products that have been treated in a manner to reduce the microbial count beyond normal pasteurization, packaged under extreme hygienic conditions and have a
defined prolonged shelf-life under refrigeration conditions”
helf-life of up to 90 days
Fluid Milk – Pasteurized: Shelf-life
Most critical factors affecting the shelf-life of pasteurized dairy products is the temperature of storage
Shelf-life of pasteurized milk is determined by the level of contamination with Gram-negative psychrotrophic bacteria
Spoilage at refrigeration temperature – growth of Pseudomonas spp.
Fluid Milk – Pasteurized: Effect of Light
CHEMICAL REACTIONS INDUCED IN MILK BY LIGHT
flavor changes, loss of vitamins and other nutritional components
Wavelengths ranging from 420-550 nm
Fluid Milk – Pasteurized: Gases
OxygenImportant role in the light-induced development of off-flavors
Addition of Carbon dioxideInhibits growth of bacteria
Extends the shelf-life under refrigeration
Fluid Milk – Pasteurized: Packaging Materials
Traditionally Packaged in refillable glass bottles
TodaySingle-serve paperboard cartons and
plastic containers
I. Fluid Milk – UHT MilkUHT Milk
“Milk which has been subjected to continuous –flow heating process at a high temperature for a short time and which afterwards has been
aseptically packaged”
Fluid Milk – UHT Milk
Process DescriptionSterilization
UHT can be classified either directly or indirectly heatedPackaging
Aseptic Packaging Most widely used are paperboard, alufoil, plastic laminate carton and
plastic container
Fluid Milk – UHT: MicrobiologySPORE CAPABLE OF SURVIVING UHT PROCESSING
Geobacillus stearothermophilusBacillus subtilis
Bacillus megateriumBacillus sporothermodurans
Paenibacillus lactis
HHRS or HRSHighly heat-resistant spore former
Fluid Milk – UHT: Nutrition
Reduction of Nutritive Value can occur:1. During UHT treatment2. During Storage after packaging
Temperature, Initial Oxygen Content and Nature of the Packaging MaterialPlays a Function in Nutrient Loss
Unaffected Components Affected Components
Fat, Fat-soluble Vitamins, Carbohydrates, and Minerals Water-soluble Vitamins, Proteins
Fluid Milk – UHT: NutritionVitamins
Are more stable under UHT processing conditions
Unaffected AffectedFat-soluble Vitamins (A, D and E)
Water-soluble Vitamins (Riboflavin, Nicotinic Acid and Biotin)
Heat Stable
Folic Acid, Vitamin C and B12
Limited amount of oxygen, ascorbic acid loss is minimal
Fluid Milk – UHT: NutritionVitamins
DETERIORATION DURING STORAGE IS DEPENDENT ON
Oxygen Levels low oxygen levels can be achieved by effective oxygen barriers
Temperature
Exposure to Lightuse of opaque containers
Fluid Milk – UHT: NutritionProteins
This undergoes greatest change during UHT processing and storage
Alterations is related to flavor, gelation, sediment formation, fouling of heat transfer surfaces, loss of nutritional value and browning
Severe heat treatment cause up to 80% denaturation
Fluid Milk – UHT: Biochemical and Physical Aspects
PROTEASES & LIPASESGreatest concern
Shelf-life of UHT milk is limited by age gelationOnce the milk has gelled it’s the end of its shelf-life
Fluid Milk – UHT: Biochemical and Physical Aspects
FACTORS AFFECT THE RATE OF GELATION
ProteolysisSeverity of Heat Treatment
Storage TemperatureBacteriological Quality of the Milk
Milk Solids Content
Fluid Milk – UHT: Biochemical and Physical Aspects
Preventing Gelation
Use of High Quality Raw MilkIndirect Heating System
Addition of Sodium Hexametaphosphate (SHMP)
Fluid Milk – UHT: Flavor
Fresh UHT milk is characterized by a poor flavor, noticeable “heated” flavor and a sulfurous odor
Oxidized or rancid off-flavors develops depending on the level of oxygen and storage temperature
Fluid Milk – UHT: Packaging Materials
Most common is paperboard laminate carton
Fermented ProductsFermented Milk
Products from milk homogenized or not, pasteurized or sterilized and fermented by means of specific microorganisms
Fermented ProductsYogurt
The most important of the fermented milk productsKefir Koumiss
Alcohol content of 0.5-2% Alcohol content of 2-3%Contains carbon dioxide, formed by heterofermentative, aroma-
forming lactic acid bacteria
Fermented Products – Packaging Materials
Butter and Spreads - Composition
ButterA fat obtained from milk
80-82 % Milk Fat Content2 % Total Fat-free Dry Milk Solids
16 % Moisture Content
Butter and Spreads - Production
MILK FAT IS CONCENTRATED BY:1. Separation of the milk2. Churning of the cream
Butter and Spreads - ProductionClassifications of Butter1. Unsalted Butter – prepared from sweet cream2. Salted Butter – has a salt content of 0.2-2 % prepared from sweet cream3. Unsalted Butter – prepared from sour cream4. Salted butter – prepared from sour cream
Butter and Spreads – Shelf-lifeINFLUENCED BY
Microbial, Enzymatic and Chemical ReactionsSusceptibility to readily absorb odors
Natural Antioxidant in ButterTocopherol (Vitamin E)
Butter and Spreads – Packaging Requirements
OxidationButter is very susceptible to light-induced flavors
Degree of Deterioration depends onLight source, wavelength of light, exposure time, distance and beta-
carotene content
Butter and Spreads – Packaging Requirements
Water Vapor PermeabilitySurface desiccation of butter results to discoloration
(primrosing)
Butter and Spreads – Packaging Requirements
Odor Permeability
Satisfactory Packaging Material Protect the butter from odor compounds
Butter and Spreads – Packaging Requirements
Packaging in Current Use
RETAIL PACKAGING OF BUTTER
Aluminum foil laminated either to greaseproof paper or vegetable parchment or paper alone
OTHER TYPES
Plastic tubs