Process Optimization

Optimization of Retort Processing & Production of Shelf Stable Ready to Eat Retort Food

In order to produce high quality safe  Retort Food, it is very important to optimize the retort processing. The product should be sterilized properly to make sure that it is safe for consumption. At the same time, it should not be over cooked or over processed. Because over sterilization kills the taste and food appeal of the product.

The pictures shown below are similar Retort Processed Food processed by two different processors.

The above picture shows clearly the importance of proper optimization of the retort processing. The left side picture shows the retort processed baked beans produced by HEINZ and similar product produced by some other ’ xyz’ company. Both products are available in the market. The second food is badly over processed and lost all the basic qualities of the target food and finally converted as a Junk food.
HEINZ produces more than 5 Million cans per day from their single factory where as the other company produces only negligible quantity and struggling to stay in the market.

Why similar food processed by two companies shows such huge difference in quality ?
How to produce high quality retort food ? We are discussing the reasons here.

Many companies are producing such junk food and the consumers feel that the canned food / retort food are only compromised food which have less qualities and taste than its fresh equivalence. But it is not true. Properly optimized canned food / retort food can be produced with the taste and quality almost equivalent or sometimes batter than its fresh equivalents.

What should be the qualities of Retort Food ?

n Safety – should be free chemical additives and preservatives

n High Nutritional value – proteins, fat, carbohydrate, vitamins, minerals etc.

n Good Taste

n Food Appeal – is the sum of sensory characteristics: appearance, flavor, smell and texture.

n Suitability and Consumer Value :- freshness, shelf stability, suitability for the intended purpose and convenience.

n Reasonable price.

What are the effects of Over Sterilization / Over Cooking of Retort Food ?

Any application of heat will alter the nutrients and the sensory characteristics of a food product in a number of ways.
p Denaturing and Coagulation of Proteins

p Gelling and Liquifying of Starches and Carbohydrates.

p Decrease/destruction of Vitamins & Other Growth Elements.

p Caramelization of the Sugars

p Browning caused by “Maillard Reactions”.

p Pigment Breakdown and the Denaturing of Spices.

The Right Degree of Cooking (Co value) is defined as the specific stage of cooking, at which any given food is at its best (flavour, texture and appearance wise). This degree is as specific for each food item and it is subject to individual judgment.
So it is very important to optimize the retort processing and make sure that the food is not over cooked during the sterilization. The processor can follow the Co value ( Cook Value) estimation during the sterilization to make sure that the products are cooked properly and not over cooked.

What are the effects of under-sterilization ?

The under-sterilized retort food may be affected by different types of Bacteria. The bacteria / spores found in retort food include Psychrophiles ( survives at -12 to +20 deg C), Mesophiles ( survives from 10 to 45 deg C) and Thermophiles (from 40 to 70 deg C). The bacterial spore is not, in itself a hazard to the thermally-processed products. It is the eventual germination, outgrowth and proliferation of organism resulting in spoilage.
The Psycrophiles and Mesophiles may have the spores of Clostridium Botulinum which produces a fatal toxin called Botulin results of the illness called Botulism. This toxin is very dangerous and is even believed to be a potential bio-weapon as it is so potent that less than 1 microgram to kill a person, a drop could kill 100,000 people and 1 pound of it can kill the entire human population.

So it is very important to implement the proper technology for retort processing applications. The proper technology and optimization of the processing makes the food equivalent to its fresh equivalence in all respects, including colour, taste, food appeal, flavor, vitamins, proteins, nutrients etc where as improper processing results in the production of unsafe junk foods with poor quality.

How to develop Retort Processing Technology ?

Actually speaking, there is no specific technology for processing any specific product in any specific flexible containers. But there are good guidelines for processing the food in flexible containers.
Fo-value recommendations and technology guidelines from any technologists or institutes are to be understood as general guidelines at best and should always be applied in trial runs followed by microbiological analysis.

Whenever the processor receives the processing technology from a technology transfer center or a food research institute, it should be noted that the mentioned technology was developed only for that particular product, which was processed in a particular type of retort (may be in a small pilot retort), with a particular recipe and formulation, with specific pH value and with specific precooking procedures and cooling method.

That specific process technology should be applicable only for that specific product which should be processed in similar conditions while it was developed by the concerned technologists. It is meaningless to apply the same process technology to other types of dissimilar products. The processor has to develop own specific technology for their specific product based on the type and characteristics of the products, type of packing material, type of retort, type of sterilization method etc. by following the international guidelines for the technology development.

Whenever the processor changes any of the following parameters, he has to re-standardize the existing technology to make it suitable for the new product.

The container size and type (flat or stand up type pouches with different capacities)

Orientation of pouches inside the retort (vertical or horizontal)

Material and structure of pouches (aluminum foiled or microwavable),

type of packing material (cans, trays or pouches)

Head Space and amount of vacuum present inside the pouches.

Product Formulation

Product quantity


Retort (type, size, or processing method)

pre processing techniques

Cooling method etc.

Retort Processing Technology – What it should contain ?
When a processor takes the retort processing technology from a technologist or from an institute, he should get the following information for that specific product.
Minimum Fo value to be achieved for the safe production

Cook value ( Co value) of the product

Maximum temperature (holding temperature) which the ingredients can withstand before it loses its qualities

Amount of Over pressure required, how much pressure and at what time to be applied ?

Filling temperature and tolerance of the initial product temperature

Cooling method and time

Sterilization Time

Orientation of the containers and maximum and minimum load in the retort.

Pre-processing / cooking techniques.

pH value (before and after processing)

Water activity value ( before and after processing)

What precautions to be taken if there is a drop in the initial temperature at the start of the process ?

What precautions to be taken if there is a problem in steam / air / water supply line during the processing ?

How to take care of change in the cooling water temperature, which varies depends on the seasons ?

How to adjust the process time, if the retort load is less than the pre-defined quantity ?

System Analysis ( present method of retort processing)

Many retort processors are producing the food without optimizing the retort processing properly. They are mainly concerned about the safety of the product. The quality is badly compromised in such cases.

Normally they take the process technology for any particular product from any of technology transfer centers. They do not realize that the mentioned technology was developed only for a particular product processed in a specific container in a specific type of retort. It will not hold good, if the processor changes any of the pre-defined conditions.

But the processor implements the same conditions for many other dissimilar products. They fix a particular filling temperature, holding temperature, holding time ( sterilization time), cooling time, over pressure etc in the retort controls and process different types of dissimilar products under similar conditions. Whether it is rice, vegetable, chicken, fish, meat or soups, the processor fix a pre-set program in the retort which includes the fixed come up time, holding time, sterilization time, over pressure and cooling time.

This is mainly due to ignorance about the process technology and also to implement short cuts to make work easier.

This method will be very useful if the processor is using a specific retort only to produce one type of products. For example, he can pre-set the conditions if produces only rice products in one retort. He also should make sure that all the pre-set conditions are achieved properly always and no variations or deviations occur.

The final result of processing different types of products using pre-set conditions in the retort will be that some products ( which matches with the pre-defined conditions) comes out good where as many others will be over processed, junk food without any good qualities of its fresh equivalence. Such products may show good colour and taste, but it may be very poor in nutrient values.

Improper Retort processing leads to the following damages to the Processor :-

Spoilage of products will be more
Reduction of shelf life of products
Loss of food qualities including taste, color, flavor, aroma, nutrient values etc.
Bursting, seal breakage and spoilage of pouches during processing
Under sterilization of the products leads to the development of poisonous bacteria called Clostridium Botulinum which is harmful for human beings.
Variation in the qualities of the products processed in the same retort
The failure of the products in the market even though the sample pouches pass through the microbial tests.
Rejection of the products from export market
Non approval from export inspection authorities like FDA / USDA etc