Food Engineering: Principles of Canning PDF

**Food Engineering: Principles of Canning** **Objectives** After completing this lesson, you will be able to: Explain the application of food engineering in food technology. Describe the utilization of knowledge on the desired product, the raw material(s) the physical principles in that were a...

**Food Engineering: Principles of Canning** **Objectives** After completing this lesson, you will be able to: Explain the application of food engineering in food technology. Describe the utilization of knowledge on the desired product, the raw material(s) the physical principles in that were applied in developing the process(es) and devices/tools/machines to produce the food product(s) with beef as raw material and canned corned beef as the food product exemplars. Explain the engineering aspects of processing of other food products. **Food Engineering** is the application of science and technology to design sustainable and environmentally responsible food processes for manufacturing **safe**, **tasty**, **healthy**, **convenient food products**. It combines basic principles of engineering (fluid mechanics, heat transfer, and mass transfer), math, and science (biology, chemistry, and physics) with advanced courses in food chemistry, microbiology, and food processing operation, and engineering design. The manufacture of canned corned beef is an example of food engineering. **Food Engineering** develops technologies composed of; - process(es) - mechanical device(s) To convert material(s) into food product(s) The technology of canning was developed by using knowledge and information on: - the product - raw material(s) - and physical sciences - microbiology We will learn how this is accomplished using the thermal processing of corned beef as an example **The development of a technology can start from either a raw material or a product. The need for a technology could arise from the need to utilize materials from :** - excess production of a commodity like fruits, vegetables, fish, etc., - processing waste, e.g. materials that are below standards, e.g., over or undersized; waste parts of the material, e.g., peels, seeds, juice, etc., - decreasing demand for an existing product due to changes in consumer demand, changes in the market, environmental, socio-political-economic changes. - import, more sustainable, cheaper substitute **Banana ketchup** was first produced in the Philippines during World War II due to a wartime shortage of tomatoes but a comparatively high production of bananas. Filipina food technologist **Maria Y. Orosa (1893--1945)** is credited with inventing the product. The development of a technology can start from either a raw material or a product. The need for a technology could arise from the need to utilize materials from : - excess production of a commodity like fruits, vegetables, fish, etc., - processing waste, e.g. materials that are below standards, e.g., over or undersized; waste parts of the material, e.g., peels, seeds, juice, etc., - Decreasing demand for an existing product due to changes in consumer demand, changes in the market, environmental, socio-political-economic changes. A specific product can arise from the need for products for specific use, market, condition/environment.For example, canning was invented after prolonged research by **Nicolas Appert of France in 1809,** in response to a call by his government for a method of preserving food for army and navy use. Space ram is instant noodles designed for consumption while in space. The original **instant ramen** was in developed by **Momofuku Ando**, when he saw the long lines of people buying noodles For products, the basic considerations are **CONSUMER NEEDS & DEMAND FOR QUALITY PRODUCTS:** - Safe - Nutritious - Good eating quality (Sensory Quality) - Convenient - Affordable to the target consumer For corned beef as a sample product, what specific characteristics were considered in the processes and mechanical devices that were developed or utilized? - Safe from hazards: biological, chemical, physical - Shelf stable, will not spoil at ambient temperature for a relatively long period (1 year or more), protected from contamination (in a sealed impervious container) - High nutritional value- its natural nutrients or a substantial amount are still found in the product - Good eating quality (sensory quality), as close as possible to freshly-prepared product or better - Convenient, easy to transport, to use etc., Note: Each will be prioritized according to the need or gap What could make beef unsafe to eat? By categories of food hazards, the following are considered in beef: - **Biological**: parasites, insects, microorganisms - **Chemical**: toxins which could be naturally occurring, e.g. prions, an abnormal form of protein that is developed in cows causing mad cow disease (BSE or Bovine spongiform encephalopathy); from contamination from the environment like heavy metals or pesticide residues, as by-products of chemical changes during spoilage; and more recently, nano plastics - **Physical**: metals, glass and other small abrasive materials One traditional method of extending the shelf life of beef is by salting or the production of corned beef. It would keep for 3-5 days when refrigerate. Other preserved products are the dried beef or jerky and sausages. Thus, corned beef would still need refrigeration or freezing so it would last longer! The jerky is dry and tough, and sausages can be dried to last for 1 -6 months.  There are the canned varieties that would keep for 1 -- 3 years or more. **Definition of Canning** Canning renders commercially sterility in a food materials. What does commercial sterility mean? This is achieved by application of heat, alone or in combination with other appropriate treatment, sufficient to render the food free from microorganisms capable of growing in the food at ambient conditions at which the food is likely to be held during distribution and storage (PNS/BFAD 07:2006 ICS 67.020). - The product is packaged in hermetically sealed containers so that it will be protected from recontamination - The thermal process also cooks the food and would have positive or negative effects on quality, depending on the material that is canned. - Nutritional quality, e.g. loss of vitamins - Sensory quality, e.g. texture, color, taste **How is commercial sterility attained?** - The thermal or heat processes given the products are sufficient to eliminate all pathogenic and spoilage microorganisms. - Sufficiency of heat treatment depends on the thermal process or temperature and time of exposure to heat or heat treatment. - This requires the establishment of a Process Schedule for the manufacture of a specific product. **What is a Process Schedule?** An established process schedule is specific to that product, preparation, thermal processing system, and container. It is required in the issuance of the LICENSE tTO OPERATE (LTO) issued by BFAD. Process schedules and MUST NOT BE ALTERED without consulting a processing authority (BFAD). The development of a Process Schedule is outlined below. How do you know that the heat treatment is sufficient to render the food safe and that it will have the desired long shelf life? To be sure that the heat that is applied is sufficient, the heating process should target the most heat resistant pathogenic and spoilage microorganism. - The presence of the most heat resistant pathogenic (disease-causing) and spoilage microorganisms in the material is an important characteristic of the material. - For canned products, the primary concern is **Clostridium botulinum**, although it is not the most heat resistant. - It produces a dormant form called a spore. These spores are extremely hard to kill with heat (resistant), anaerobic and may survive for many years, waiting for a chance to grow. Why are the identified properties of the raw material, i.e., protein content and pH, important considerations in canning? The main purpose of heating or thermal processing is to reduce the microbial load of the material and to prevent contamination. To be sure that the heat that is applied is sufficient, the heating process should focus on the most heat resistant microorganism. - The presence of the most heat resistant pathogenic (disease-causing) and spoilage microorganisms in the material is an important characteristic of the material. For canned products, the primary concern is Clostridium botulinum,, although it is not the most heat resistant. - Vegetative cells will multiply rapidly and may produce a deadly toxin within 3 to 4 days of growth in an environment consisting of: - A moist, low-acid food. - A temperature between 40-120° F (4-40° C). - Less than 2% oxygen. - It produces a dormant form called a spore. - These spores are extremely hard to kill with heat (resistant), anaerobic and may survive for many years, waiting for a chance to grow. Therefore, - An improperly processed can of food provides an ideal environment for spores, since the bacteria can survive in anaerobic environment. - Clostridium botulinum produces an extremely potent neurotoxin among the deadliest poisons known. Growth conditions Cl. botulinum - Temperature range: GROUP 1 (Toxins A.B.F - proteolytic, mesophilic strains): 10 to 48 C - Minimum pH: 4.6 - Minimum Aw: 0.94 (10% NaCl) - GROUP 2 (Toxins B,E,F - non-proteolytic, psychrotrophic strains) 3 to 45 C - Minimum pH: 5.0 - Minimum Aw: 0.97 (5% NaCl) - Optimum Temperature for toxin development: 35°C (95°F) - pH range: 4.6 - 8.9 - Lowest reported Aw for growth: 0.95 this became the basis in the classification of foods between high acid and low acid foods. A low-acid food is defined as a food having a pH of more than 4.6, A high-acid food is defined as a food with a pH value of 4.6 or lower. **Measure of Thermal Resistance** When bacteria are subjected to moist heat at lethal temperatures (as for instance in a can of food during retorting), they undergo a decimal or logarithmic order of death rate. The time interval required to bring about one decimal reduction (i.e., a 90% reduction) in the number of survivors is the decimal reduction time, called D value, the measure of thermal resistance of microorganisms. **Measure of Thermal Resistance** Determination of the D value facilitates estimating the amount of time required to reduce the microbial load from an initial number to a target level. **Example:** Estimate the time required to reduce the number of Bacteria X with a D115 = 2 mins from an initial load of 1 million to 1 per gram of beef. Time required = Change in no. of bacteria x D value = (Initial no - Final no) D value = 12 min A 12D minimum process requirement for safety from botulism is the standard. - What does the D121.1 of 0.1 -.23 fo C. botulinum mean? - It will take that number of minutes to reduce the population of the bacterial spore by 1 log cycle. - How many minutes would it take to reduce the population of 106 to 101 or by 5 log cycles? **Z value** The change in temperature that changes the D value by a factor of 10 or organism's heat resistance by a factor of 10 It measures the effect of temperature on the D value, i.e., the change in the death rate based on temperature. If D-value versus time is plotted -- again on a logarithmic scale, the graph looks very similar to the one previously. This one is called the Thermal death time (TDT) curve. This time the straight line graph means that if you change the temperature by a certain amount, the D-value will change by a factor of 10. If you had changed it by twice that amount, D-value will change by a factor of 100. The change in temperature to cause a factor of the ten change in D-value is referred to as that z-value. The z-value for Bacillus stearothermophillus is 10°C. Remember the D-value for this microorganism at 121°C is 4 minutes. Therefore if you held the containing this microbe at 111 oC (10 oC, or one z-value, less than 121 oC), D-value would be 400 minutes. That is, for Bacillus stearothermophillus, 4 minutes at 121°C will have the same effect (one log reduction in spores) as 40 minutes at 111oC, which would have the same effect as 400 minutes at 101°C. It is obvious why using high processing temperatures is an advantages. The D-values of different microbes differ greatly -- for example, the D-value of Clostridium botulinum at 121°C is about 0.21 minutes. However the z-value of microorganisms is close to 10°C. Examples of high-acid foods include jams and jellies, pickles and most fruits. Because there is no fear of Clostridium botulinum growth, these foods require much less heating than low-acid foods. To be safe, such foods need only to reach pasteurization temperatures. pH value of 3.5 or less, 175°F (79.5°C) pH range between 3.5 and 4, 185°F (85°C). pH range of 4 to 4.3, 195°F (90.5°C). pH value of 4.3 to 4.5 210°F (99°C). Yeast and molds are the common spoilage organisms in high acid foods, however, cases have occurred in which the growth of yeast or mold has consumed natural acids present in the food and allowed the pH of the food to rise to the point where Clostridium botulinum grows and botulism toxin is produced. Most vegetables, meat and poultry foods fall into the low-acid food category. Temperatures of 240°F (115.6°C) or greater are commonly used and process times may range from 20 minutes to several hours. Some foods primarily tropical fruits and tomatoes, vary in acidity and may have a pH more or less than 4.6, depending on the season and variety. When preserving these foods, it is best either to treat these foods as low-acid foods or else add an acidifying agent such as vinegar or citric acid to lower the pH well below the critical value of 4.6. These foods would then be treated as acidified foods for regulatory purposes and processed as anyother high-acid food. Knowledge on the material is important in developing the process and inventing the corresponding mechanical devices. What are the important characteristics of beef in the canning process? In the case of beef, it has been determined that it has high protein content and is a low acid food. Corned beef has low liquid content Beef normally reaches its lowest pH value of 5.4 to 5.7 at 18-24 hours after slaughter. After the lowest pH level is reached, the pH starts to rise again slowly but steadily. By the time it reaches pH of 6.5, it is starting to decompose. It is expected that Cl. botulinum could grow in beef. The heat treatment should be sufficient to reduce the estimated load of Cl. botulinum in thermal processing of beef. For canning in particular, the pH of the food plays a key role in determining the extent of heat processing needed to insure a safe final product. Other Factors. the thickness or viscosity of the product, the size of the food particles, the dimensions of the container and the temperature of the cooking medium. How much is sufficient heat to attain commercial sterility of the canned beef? A Process Schedule is required. The thermal (heat) process selected by the processor required under the conditions of a manufacturer for a given product to achieve commercial sterility. Thermal processing parameters such as Initial temperature (IT) of product Process time Process temperature Critical factors (as needed) e.g., minimum headspace and maximum thickness (consistency) for agitating processes Maximum pH for acidified products The product type and style e.g., chili with beans, chili without beans The container type and size, and e.g., 300 X 407 can, or 145mm X 200mm X 19mm pouch The thermal processing system e.g., aseptic, continuous rotary retort , or water spray retort *NOTE: An established process schedule is specific to that product, preparation, thermal processing system, and container.* How much is sufficient heat to attain commercial sterility of the canned beef? HEAT PENETRATION TESTS Monitor the rate of change in temperature of the food inside the container as it is being heated in a specific retort system Temperature sensor or thermocouple located in the product at the slowest heating region (cold spot) of the container Use heat penetration data to "mathematically define" the heating rate Where is the slowest heating point? Slowest heating region or container cold spot depends on the: Type of product, Container type and size, Thermal processing method/sys Heat transfer mechanism How much is sufficient heat to attain commercial sterility of the canned beef? Where is the slowest heating point? The critical point is the cold spot in the can. The assumed cold spot of a can or jar heated in a stationary vessel is one-third from the base for convection heating products, and at the geometric center of the container for conduction heating products heated by conduction (Potter and Hotchkiss 1998) Modes of heating Convection Conduction Convection/conduction Induced convection NOTE: The product's mode of heating might change during processing, so temperature change is monitored at 2-3 points in the can during heating. Particle to particle heat transfer with no particle movement Product is typically viscous with little free liquid Container's geometric center is slowest heating region Examples- refried beans, pumpkin, stews, corned beef hash, etc. Simple heating or straight line  Particle to particle heat transfer with particle movement Product typically less viscous with free liquid Slowest heating region is usually 1/4 container height from bottom but can vary Examples- broths, brine packed products, (olives, green beans, carrots, etc.) Simple heating or straight line 2 scientific methods for determining process schedules (Thermal Processes) that will achieve the sterilization (Fo) value for a given product The general or graphical method, and The formula method What mechanical devices will be needed? Tools/devices/machines to convert the material (beef) into a product of desired quality.  Mechanical Devices for the Canning Process Boiler -- mechanical device for Steam production. Exhaust Boxer- a steam tunnel where the product in cans are made to pass to attain a set temperature upon exit. Filled with food, open containers are passed through an \'exhaust box\' in which steam is used to expand the food by heat and expel air and other gases. When the container cools down, the steam condenses and a vacuum is produced. Since thermal processing is at high temperature, allowance should be provided for the expansion of the can and the content  Can sealer - for hermetic seaming of the cover to the body of the can. Po  Retort/Pressure cooker for heating with pressure. Cooling vat - container for efficient cooling of the cans after processing