standardization of milk

Standardization of Milk

Standardization of milk refers to the adjustment which means rising or lowering of fat and solids not fat levels of milk. The standardization of milk is commonly done in case of market milk supply and also in case of manufacture of milk products. e.g. condensed milk, milk powder, ice-cream and cheese etc. the standardization is mostly done to have a uniform milk fat content in the finished dairy product. In India, milk is toned to 3 % fat or double toned 1.5 % by standardizing the fat content of milk and thus volume of milk is increased so that the milk can be supplied to the consumers at low price and to a large population.

Procedure:

1. Pleasure the quantity of whole milk.
2. Find out the fat SNF and Ts content
3. Measure the quantity of skim milk powder available or cream.
4 .Determine the fat % and SNF % of skim milk/skim milk powder/ cream.
5. Decide the fat level or SNF level of the milk to be standardized.
6. Calculate the requirement of skim milk/skim milk powder/cream by person’s method.

1. For fat adjustment
B        (C-B) or (B-C)
                 
A         (A-C) or (C-A)

A = Fat % of cream
B =  Fat % of skim milk
C = desired fat %on the final product
(A-C) or (C-A) = Represent the quantity of skim milk
(B-C) or (C-B) = Represent quantity of cream with high fat % B for SNF Adjustment
Y         (Y-Z) or (Z-Y)

X         (x-Z) or (Z-x)
X = SNF content of whole milk/cream
Y = SNF content of skim milk / powder
Z = Desired level of SNF
(x-Z) N (Z-x) = Represent the required quantity of skim milk
(Y-Z) N (Z-Y) = Represent the required quantity of cream / whole milk.
Weigh the required quantity of skim milk / skim milk powder cream and add in to the vat along with the material of which fat and SNF level is to adjusted.
Mix the contents thoroughly.
Take the fat / SNF content of the final product to check their desired level.
Sent for further processing and packaging.

Packaging

Definition:

Packaging means placing a commodity into a protective wrapper or container for transport and storage or it can also be defined as a tool that protects and contains goods with the aim of minimizing the environmental impact of our consumption.

The packaging concept is determined by the demand of both the consumer and the product. New technological development, environmental awareness and changes in the consumer market force the packaging technologists to consider an increasing number of factors when designing a package. Packaging materials provide a sort of inert barrier that prevent the interaction of food products with the external environment.
The packaging material should satisfy the following conditions.
It must protect and preserve the commodity from the time it is packaged till the product is consumed.
It must be suitable for the selected sales and distribution pattern.
It must protect and preserve the commodity from the time it is packaged till the product is consumed.
It must be suitable for the selected sales and distribution pattern.
It must be attractive to the consumer.
It must be easy to open, store and dispose.
It must facilitate the handling, storage and distribution.
It must protect against biological, chemical and distribution damages.
It must inform the consumer through the medium of labeling.
It must impart security to the product through a tamper evident design.
It must act as a marketing and advertising tool.
It must protect the environment by taking the responsibility of empty packaging material after its use.
It must be economical i.e. it should neither burn the purse of the consumer nor the producer.

Packaging Materials for milk and dairy products

The packaging materials include paper and paper based products (coated or lined), glass, tin plate, aluminium foil, timber (wood), plastics and laminates.

Paper and paper based products

The paper and paper based products form an excellent packaging material for milk and milk products. They may be kraft paper, grease proof paper, vegetable parchment paper, glassine paper, wax coated paper, plastic coated paper, paper boards, solid fibre boards, liner boards, box boards etc.
The papers are used in the form of boxes, bags, wrappers, cartons, cups etc. The advantage of using paper is that it is weightless, capability for printing on the surface, low cost and easy disposability. The disadvantages include low wet and tear strength.

Glass

The glass may be transparent or opaque. Glass is used in the form of bottles, tumblers, jars, jugs etc. The advantages cited for glass as a packaging material include its strength, rigidity, ability to have a barrier for water and gas and inertness to chemical substances. The disadvantage is its heavy weight, and fragility.

Tin plate

It may be made up of a thin sheet (0.025 mm thick) of mild steel coated on both sides with a layer of pure tin. It is desirable to have an internally lacquered can, which provides better resistance to corrosion. The advantages cited for tin containers as a packaging material are their good strength and excellent barrier properties. The disadvantages are their high cost, heavy weight, difficulty in closing the lid of the container, and disposal. The containers are mostly used in the form of can.

Aluminium foil

The common thickness of the foil used is 0.012 – 0.015 mm. To increase corrosion resistance, it may be lacquered (coated with lacquer) or a thin film of plastic can be applied for packing dairy products. The advantages of these containers are good barrier properties, grease proof, non-absorption, shrink proof, odourless, tasteless, hygienic, non toxic, opaque to light, bright in appearance etc. The demerits are its low tear strength, susceptibility to strong acids and alkalis. It is mostly used in the form of wrapper, carton and box.

Timber

The required qualities for the timber to act as a packaging material are it should be free from odour, have an attractive appearance, and required mechanical strength. It may be treated with casein formalin, or sprayed with paraffin wax or plastics or to make it more water resistant and to avoid the passage of timber taint to butter. It is generally used in the form of a box, tub, cask or barrel.

Plastics

The use of plastics in packaging has made tremendous progress in recent years all over the world. A wide variety of plastics can be used as thermoformed, injection moulded or blow moulded containers, such as bottles, cartons, cups, boxes etc. The merits of rigid plastic containers are its low cost and ease of fabrication. The demerits cited are lack of product compatibility, low barrier properties, plastic deterioration, lack of resistance to high heat and fragility at lower temperatures.  Flexible plastic packaging films are used as wrappers or sachets or bags or pouches for packaging milk and dairy products. The flexible plastics can be classified in to two types.

Low polymers

They include cellophane (coated with plain or nitrocellulose / saran / polyethylene), treated with cellulose etc.

High polymers

Polyethylene, polypropylene, polystyrene, poly vinyl chloride, poly vinyledene chloride (cryovac), rubber hydrochloride (pliofilm), polyester, polyamide (nylon), saran (a mixed polymer), etc. form good packaging materials.
The merits cited for flexible packaging films are they can be easily applied and the packaging process can be readily mechanized; loss of moisture from the dairy product is practically nil; it confers protection to dairy products against attack by microorganisms, insects etc. The demerits are: not all technical problems in film packaging have been solved; failure to obtain a perfect seal and removal of all air before packaging may lead to spoilage; the most careful attention to detail is necessary, else faulty production will result; etc. Care has to be exercised in selecting food grade plastics for packaging of milk and dairy products; otherwise toxicity, if any, from the package will be transferred to the products.

Laminates

They are formed by combining the complete surfaces of 2 or more webs of different films with the primary object of overcoming the defects of single films. Usually laminations are made to strengthen the film material, to improve barrier properties, to improve grease resistance, to provide a surface that will heat seal, etc. Some of the typical laminates available for packaging are paper-polythene, cellophane-polythene, aluminium foil-polythene, paper aluminium foil-polythene, polyester-polythene, etc.

ASEPTIC PACKAGING

When comparing the aseptic packaging technology to the classic sterilization technology, the latter is based on filing non-sterile products in to non-sterile containers under non-sterile conditions. It is then followed by the sterilization of the container. Very high retention of organoleptic and nutritional food qualities coupled with better economics are claimed as the advantages of aseptic filling. The following requirements are essential for the aseptic packaging.
1. The product has to be pre-sterilized and sterile conditions have to be maintained during transfer and filling.
2. The equipment parts that comes in contact with the product including all pipe­lines for product, gas and air have to be pre-sterilized.
3. All the required areas including the atmosphere around the filling lines have to be maintained sterile.
4. The packing materials / containers have to be sterilized.
5. Use of packing material or containers that are impermeable to germs.

DAIRY EFFLUENT/ WASTE WATER TREATMENT

The very nature of the different operations involved in dairy, irrespective of the products size, generate waste water of different magnitude. The dairy is one of the major contributors among the food industry both in terms of value and effluent. The biggest share comes from cheese and ice cream factories. The relatively high concentration of organic matter in the dairy effluent makes it peculiar in its class and this results in a higher biological oxygen demand (BOD). This kind of effluent should not be allowed to mix up with the municipal waste as it will result in a shock load.

Great care has to be exercised while discharging the dairy waste water into the general pool as they impose relatively high oxygen demand. Lactose is converted into lactic acid resulting in decrease in its concentration, when dissolved oxygen is insufficient for oxidation.

This in turn will lower the pH to a point when casein is precipitated (The isoelectric point of casein is at pH 4.6). Due to economic reasons involved in the effluent treatment, the dairy industry is very slow in taking up the treatment aspects. With increasing social awareness about the environment, the dairy industry is forced to treat its effluents effectively and efficiently before disposal into the public drainage.

Source of dairy waste

The degree of waste produced in a dairy plant varies depending upon the products prepared and the home keeping practices. The dairy waste consists mainly of raw materials lost during handling and processing and cleaning materials carried into the processing water. The composition involves a substantial concentration of fat, milk, protein, lactose, lactic acid, minerals, detergents and sanitizers.
The majority of the pollutants are dissolved in either organic or inorganic form. Equipment cleaning along with whey and butter milk contributes to the majority of the organic load. The unavoidable waste generation process include rinsing, cleaning and sanitizing of pipelines and equipment start up, product change over and shut down of HTST and UHT processes, losses during the filling operations, spill over of lubricants from pipelines, joints, valves and pumps etc.

Composition of waste water / effluent obtained in a dairy plant

S.No	Constituents	Cheese plant	Milk receiving and pasteurization section	Casein plant	Butter, Butteroil and ghee section	Pooled Dairy Effluent
1	Total solids	2250	3620	650	3400	1650
2	Color	White	White	Clear	Brown	White
3	Chlorides	100	95	70	100	115
4	Volatile solids	25	75	55	65	60
5	Suspended solids	600	1300	100	2200	650
6	Phosphates	12	10	5	2	10
7	pH	6.7	8.2	7.7	7.1	6.1
8	Calcium carbonate	480	500	460	420	530
9	Absorbed oxygen	480	400	10	85	--
10	BOD	2150	1620	200	1250	810
11	COD	3130	2600	370	3200	1340
12	Oil and Grease	520	690	--	1320	290
13	COD:BOD	1.46	1.43	1.85	2.56	1.65

The methods available to treat dairy waste water

They are classified as physical, chemical and biological methods. The selection of a particular method depends on different factors including the physico-chemical nature of the effluent, biological oxygen demand load, quantum of the effluent to be treated, location of the treatment plant, degree of purification required and the economy of a treatment method adopted.

PRETREATMENTS

• Equalization
• Neutralization
• Separation / Clarification
  

SECONDARY TREATMENTS

• Biological Methods
  
• Activated sludge process
  
• Aerobic process
  
• Oxidation ditch / trickling filters
  
• Rotating biological discs
  
• Anaerobic digestion
  

Activated sludge

The activated sludge process is a process for treating sewage and industrial wastewaters using air and a biological floc composed of bacteria and protozoa.

Sludge production

Activated sludge is also the name given to the active biological material produced by activated sludge plants. Excess sludge is called "surplus activated sludge" or "waste activated sludge" and is removed from the treatment process to keep the ratio of biomass to food supplied in the wastewater in balance. This sewage sludge is usually mixed with primary sludge from the primary clarifies and undergoes further sludge treatment for example by anaerobic digestion, followed by thickening, dewatering, composting and land application.
The amount of sewage sludge produced from the activated sludge process is directly proportional to the amount of wastewater treated. The total sludge production consists of the sum of primary sludge from the primary sedimentation tanks as well as waste activated sludge from the bioreactors. The activated sludge process produces about 70–100 kg/ML of waste activated sludge (that is kg of dry solids produced per ML of wastewater treated; one mega litre (ML) is 10³ m³). A value of 80 kg/ML is regarded as being typical.In addition, about 110–170 kg/ML of primary sludge is produced in the primary sedimentation tanks which most - but not all - of the activated sludge processs configurations use.

Arrangement

The general arrangement of an activated sludge process for removing carbonaceous pollution includes the following items:

• Aeration tank where air (or oxygen) is injected in the mixed liquor.
• Settling tank (usually referred to as "final clarifier" or "secondary settling tank") to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water.
  

Treatment of nitrogenous matter or phosphate involves additional steps where the mixed liquor is left in anoxic condition (meaning that there is no residual dissolved oxygen).