MURANO FSTC 311

FSTC 311

FOOD PROCESSING

Current Events & Unit OperationsDr. Peter S. Murano Associate ProfessorDepartment of Nutrition and Food Science Texas A&M University138 Cater-Mattil2253 TAMU, College Station, TX  77843-2253Phone:  979-862-7955      E-mail:  psmurano@tamu.edu

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OUTLINE of TOPICS

A. Food Processing – definition and basics

B. Principles of Food Processing

C. Processing Industry Trends 2015

D . Unit Operations and Process Engineering

E. Heat Transfer Unit Operation

F. Fourier’s Law and thermal Conductivity

G. Heat Exchanger Equipment

H. Laws of Mass and Energy Conservation

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FOOD PROCESSING

is the conversion of raw food materials / ingredients

into typically packaged, more stable, consumable forms

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Indra Nooyi, CEO of PepsiCo

“we have never seen food consumers as confused as they are today”

An interesting comment… what do you make of it?

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WHY are foods processed

and what are

the general PRINCIPLES

of food processing?

MURANO EXPLORING FOOD SCIENCE AND TECHNOLOGY © 2013

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Can you SPOT the foods that are processed?

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5 Food Processing Industry Trends for 2015

Source: Food Manufacturing

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1. Innovative Solutions to Drive Down Costs

2. Energy Efficiency

3. Healthier, Natural Foods

4. A Refrigeration Strategy

5. CHINA: A Potential Growth Vehicle

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1. Innovative Solutions to Drive Down Costs

With the advent of the Internet and pricing transparency for consumers, pressures are rising for food manufacturers to be low cost. They are trying to find ways to drive more value, and are looking for:

- Innovations that can help maintain profitability

- New products to bring to market

- Modifications to product categories

Food manufacturers are also on the hunt for more cost-effective means of manufacturing, standardizing equipment, and exploring automation to minimize labor costs.

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Food manufacturers can move towards innovation and the standardization of certain product categories to drive down their own costs. Food processors can rethink their manufacturing strategies, optimizing what makes sense and developing a new cost model. In the long run, they need to have the flexibility to run products with higher margins.

Companies are trying to get improved visibility into the true cost of manufacturing their products.

Whereas before they may have looked at the profitability of a plant, they’re now diving deeper, examining the profitability of a product category, manufacturing line or even a particular stock keeping unit (SKU).

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WHAT WOULD YOUR DECISION BE …

Suppose your company produces several low-margin products, along with ones that have high margins.

The management team examines last year’s profits and losses and decides something must be done about the low margin category:

What would you do?

1. Take steps to cut production costs2. raise prices3. discontinue offering the low margin products

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Consider the information on the next slide…

While it is focused on NANOTECHNOLOGY, a new technology that can be applied to food processing, it also clearly depicts the centrality of food processing in the food production chain “from farm to fork”.

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Recall that the first food processing industry trend that we are discussing dealt with INNOVATION.

Studies of innovation show that there is a translation of promising “technoscience” into products in society.

The concept frequently used to describe a consecutive “up-valuing” of a material or technological device is the value chain model.

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What is meant by a “value chain”?

It is the series of activities required to produce and deliver a product or service.

The chain encompasses raw materials that create products to the ultimate consumption of the finished products.

Layers in a value chain have been described in terms of a sequence, comprising: suppliers, manufacturers, distributors, and consumers.

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What is this diagram telling us?

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What is this diagram telling us?

1. The VALUE CHAIN involves SUPPLIERS, BUSINESSES, CONSUMERS

2. SUPPLIERS provide or input materials to BUSINESSES

3. From these, BUSINESSES generate PRODUCTS for CONSUMERS

In order for this CHAIN to function repeatedly and successfully,

4. BUSINESSES provide PAYMENTS to SUPPLIERS so that they can

make their products

2. CONSUMERS provide PAYMENTS to BUSINESSES in order to buy

these products

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2. Energy EfficiencyThe trend toward energy efficiency is driven in large part by an increase in consumers who are concerned with the environment and what they’re putting into their bodies.

When food companies reduce energy consumption, it appeals not only to consumers for environmental reasons, but drives costs down, as well.

Thus, by reducing energy consumption, food manufacturers are reducing costs and increasing margins.

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3. Healthier, Natural Foods

Consumers have become more aware of what they’re eating; there’s been increasing interest in organic and natural foods.

From a manufacturing standpoint, this presents more challenges in terms of equipment types and how materials are processed. The formulations and handling can be different for such products, impacting how lines are set up and operated.

If a bakery is gluten free, for example, the processing is entirely different than if you were to use standard ingredients due to concerns over ingredient separation and cross contamination.

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3. Healthier, Natural Foods

CHALLENGE:

Many

consumers do

NOT equate

“healthy foods”

with

“processed foods”

From:http://windowstorussia.com/in-russia-it-is-easy-to-eat-healthy.html

Why ???

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Does packaging impact consumer perception of organic foods?(packaging is a unit operation)

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Consumer Perceptions Of Processed FoodsSome consumers feel that:

- “processed foods are less healthy”- “processed foods are junk food”- “processed foods have too many added chemicals + fat, sugar, and/or salt; artificial flavors/colors

On the other hand, some consumers are aware thatthrough food processing/food technology,

- “such foods offer enhanced shelf-life and safety”- “such foods meet sustainability goals for global needs”

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Consumer Perceptions Of Processed Foods

March 28, 2010

Consumers (43%) have a negative attitude toward processed foods, according to a study conducted by the International Food Information Council (IFIC). The study, which interviewed 1,500 adults in the U.S. who are the primary grocery shopper in their household, found that negative perceptions are deeply rooted and cross all demographics.

Source Information from this survey accessed from:

http://www.foodnutritionscience.com/articles/consumer-perceptions-about-processed-foods/

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Consumer Perceptions Of Processed Foods

Researchers discovered that both the obesity epidemic and the move toward local and organic alternatives are driving forces in this attitude shift,

and

growing concerns about the healthfulness of processed foods are leading to the de-selection of some of these foods in certain food and beverage categories.

The term “processed foods” itself also carries with it a negative perception.

“Processed Food… Nooo!”

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Consumer Perceptions Of Processed FoodsWhile consumers’ general attitudes toward processed foods are negative, there is recognition of the significant role processed foods play in their everyday diets.

In addition, some types of processed foods have more negative views associated with them than others. For example, sodium, trans fats and high fructose corn syrup are poorly perceived.

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Consumer Perceptions Of Processed Foods

Nearly all consumers eat both fresh and processed foods, and two-thirds of those interviewed consume some organic foods. However, one-third of consumers plan to reduce their consumption of processed foods in the next six months or say they have recently done so.

Some of the most mentioned processed foods consumers say they eat include cheese, canned soup, frozen meals, soda, lunch meats, chips and cereal.

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Consumer Perceptions Of Processed Foods

Foods identified as “fast” foods or “junk” foods top the de-selection list, but virtually all categories of processed foods receive a mention.

The majority of consumers (80%) are in the process of changing how they eat, and of those, 48% are doing so for improved health and nutrition. Thirteen percent cited the economy.

Consumers in this study acknowledged the positive aspects of processed foods, like convenience, value and consistency, and they do seem to understand that it is unrealistic to buy solely fresh, local and organic foods – especially during tough economic times.

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Consumer Perceptions Of Processed Foods“We know that weight is tied to both diet and exercise, but processed foods have been the primary target, mostly due to negative information that isn’t always science-based being perpetuated in the media,” says Lindsey Loving, Senior Director, Food Ingredient & Technology Communications for IFIC.

“Another issue is the use of certain ingredients in processed foods. There is a lot of misinformation out there about the purpose, function, and safety of many ingredients in processed foods, which creates uncertainty and fear.”

Processed Foods

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4. A Refrigeration Strategy

Another area that’s been generating a lot of interest is refrigeration compliance.

Companies want to take an active role in developing a refrigeration strategy for 2015, driven by Occupation Safety and Health Administration (OSHA) mandates.

Due to its damage to the atmosphere, food manufacturers must phase out R-22 refrigerants and move toward natural options such as CO2 by the year 2020.

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According to the EPA, releases of R-22 into the environment, such as those from leaks, contribute to ozone depletion.

In addition, R-22 is a greenhouse gas and the manufacture of R-22 results in a by-product (HFC-23) that contributes significantly to global warming.

The 1987 Montreal Protocol established a schedule for the phaseout of HCFCs (hydrochlorofluorocarbons), which contain ozone-destroying chlorine. Refrigerants of this type are called R-22.

The Montreal Protocol as amended is carried out in the U.S. through Title VI of the Clean Air Act implemented by EPA.

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At present, food manufacturers are making plans for the shift. There are new technologies and developments emerging around refrigeration and distribution such as skid-mounted refrigeration systems that embrace CO2

While ammonia is an environmentally friendly refrigerant, industry clients are asking for ways they can reduce their ammonia charge to below 10,000 pounds to reduce costs associated with process safety management (PSM) compliancere: ammonia system operating and maintenance.

WHAT ABOUT AMMONIA?

Ammonia (NH3) is naturally occurring and makes a fine refrigerant.

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Regulations: Ammonia is classified as a hazardous chemical so the federal government has mandated that it be subject to Occupational Safety and Health Administration's (OSHA) Process Safety Management Rules (PSM) as well as the Environmental Protection Agency's Risk Management Program Rules (RPM).

State and local regulations must also be considered. Although a PSM program is not required under 10,000 lbs of ammonia (in a food processing facility), employers have a duty to protect employees (as stated under OSHA and EPA's "General Duty" clause), and ammonia detectors are required by law.

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5. China: A Potential Growth Vehicle

Due to the emergence of its middle class, large food and beverage companies are now seeing China as a potential growth vehicle.

In addition there is the Chinese population’s growing awareness of food safety concerns, including fears about contamination and ingredients from Chinese companies.

$$$

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5. China: A Potential Growth Vehicle

Because U.S. companies have respected reputations regarding food safety and product quality, Chinese consumers are willing to pay premiums for U.S. products. Many multinational companies are now capitalizing on this opportunity to move into the Chinese market.

$$$

UNIT OPERATIONS and

PROCESS ENGINEERING

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MURANO EXPLORING FOOD SCIENCE AND TECHNOLOGY © 2013

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Reception

Cleaning

Sizing & Sorting

Peeling and Trimming

Size Reduction

The continuum of Unit Operations related to RAW MATERIALS HANDLING

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Which Unit Operation is shown here?

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Here is a BOWL CHOPPER

Which Unit Op is it used for?

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SIZE REDUCTION um… size reduction

is a key operation in food processing

METHODS of SIZE REDUCTION include chopping, cutting, slicing, and dicing:

(a) Large to medium (cheese and sliced fruit for canning)(b) Medium to small (bacon, dice carrot, sliced beans)(c) Small to granular (minced or shredded meat, flaked

nuts, and shredded vegetables

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SIZE REDUCTION is accomplished via MILLS for dry foods (cereals, grains) typically via compression and/or shear force application

Feed

Product

Two or more steel rollers revolve towards each other and pull particles of food through the nip (the space between rollers).

The main force is compression, but if the rollers are rotated at different speeds, there is and additional shear force exerted on the food

Size of the nip is adjustable for different foods

Example: roller milling

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The study of process engineering is an attempt to combine all forms of physical processing into a small number of basic operations, which are called unit operations.

Careful analysis shows that these complicated and differing processes can be broken down into a small number of unit operations.

For example, consider heating of which innumerable instances occur in every food industry. There are many reasons for heating and cooling - for example, the baking of bread, the freezing of meat, the tempering of oils.

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Because of the dependence of the unit operation on a physical principle(s), quantitative relationships in the form of mathematical equations can be built to describe them.

Such equations can be used to follow what is happening in the process, and to control/modify the process if required.

In the food industry are fluid flow, heat transfer, drying, evaporation, contact equilibrium processes (which include distillation, extraction, gas absorption, crystallization, and membrane processes), mechanical separations (which include filtration, centrifugation, sedimentation and sieving), size reduction and mixing.

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1. Ambient-temperature processing2. Processing by application of heat3. Processing by the removal of heat4. Post-processing operations

Processing Unit Operations can be classified accordingly:

Source: Ruben Morawicki, Univesity of Arkansas

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1. Ambient-Temperature Processing

• Raw material preparation– Cleaning– Sorting– Grading– Peeling

• Size reduction

• Mixing• Mechanical separations

– Membrane concentration– Centrifugation

• Fermentation• Irradiation

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Let’s briefly consider:

SORTING

- Dimensional sorting- Sorting by weight- Optical devices

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Dimensional sorting

• Screens of various designs are used to separate the food based on size

• There are two basic types:– Fixed aperture screens, and– Variable aperture screens

Flat-bed screen

http://www.eurositex.cz/en/prumyslova-sita/

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Sorting by weight

• Sorting by weight is a more precise separation than dimensional sorting

• Equipment designed to handle the products at sufficient speed is limited

https://www.youtube.com/watch?v=WF6hXpnuFVA

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OVERVIEW of OPTICAL SORTING

1. Product enters machine

2. Vibratory feeders meter product onto chute

3. Product accelerates and singulates

4. Product viewed and classified in midair

5. Product is accepted or rejected

http://www.satake-usa.com/principals-of-optical-sorting.html

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Optical sorters utilize reflected light to analyze products that have been singulated and presented to the viewing area. This singulation can be achieved utilizing low-friction inclined chutes or conveyor belts.

Specially designed optical filters narrow the reflected light into specific wavelengths that accentuate the difference between the acceptable product and the product to be rejected.

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2. Processing by Application of Heat• Heat processing using steam or water– Blanching– Pasteurization– Heat Sterilization– Evaporation– Extrusion

• Heat processing using hot air– Dehydration– Baking and roasting

• Heat processing using hot oils– Frying

• Heating by irradiated energy– Microwave and infrared radiation

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3. Processing by the Removal of Heat

• Chilling and controlled-atmosphere storage• Freezing• Freeze drying and freeze concentration

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4. Post-Processing Operations

• Coating or enrobing– Coating– Battering and breading– Seasoning

• Packaging• Filling and sealing containers

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Let’s focus next on MASS and ENERGY

Energy MatterE = mc 2

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Two very important laws which all unit operations obey are the laws of conservation of mass and energy.

Conservation of MassThe law of conservation of mass states that mass can neither be created nor destroyed. Thus in a processing plant, the total mass of material entering the plant equals the total mass of material leaving the plant, less any accumulation left in the plant.

If there is no accumulation, then the simple rule holds that "what goes in must come out". Similarly all material entering a unit operation must in due course leave.

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The law of conservation of mass applies also to each component in the starting material. For example, consider the butter fat in the milk entering the centrifuge.

The weight of butter fat entering the centrifuge per minute must be equal to the weight of butter fat leaving the centrifuge per minute.

A similar relationship will hold for the other components: the milk proteins casein and whey, the milk sugar lactose, and so on.

For example, if milk is being fed into a centrifuge to separate it into skim milk and cream, under the law of conservation of mass the total number of kilograms of material (milk) entering the centrifuge per minute must equal the total number of kilograms of material (skim milk and cream) that leave the centrifuge per minute.

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The law of conservation of energy states that energy can neither be created nor destroyed. The total energy in the materials entering the processing plant, plus the energy added in the plant, must equal the total energy leaving the plant.

This is a more complex concept than the conservation of mass, as energy can take various forms such as kinetic energy, potential energy, heat energy, chemical energy, electrical energy and so on.

During processing, some of these forms of energy can be converted from one to another. Mechanical energy in a fluid can be converted through friction into heat energy. Chemical energy in food is converted by the human body into mechanical energy.

Note that it is the sum total of all these forms of energy that is conserved.

Conservation of Energy

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Conservation of Energy

For example, consider the pasteurizing process for milk, in which milk is pumped through a heat exchanger and is first heated and then cooled.

The energy can be considered either over the whole processing plant or only as it affects the milk.

For total plant energy, the balance must include: the conversion in the pump of electrical energy to kinetic and heat energy, the kinetic and potential energies of the milk entering and leaving the plant and the various kinds of energy in the heating and cooling sections, as well as the exiting heat, kinetic and potential energies.

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To the food technologist, the energies affecting the product are the most important.

In the case of the pasteurizer, the energy affecting the product is the heat energy in the milk.

Heat energy is added to the milk by the pump and by the hot water passing through the heat exchanger.

Cooling water then removes part of the heat energy and some of the heat energy is also lost to the surroundings.

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Conservation of EnergyThe heat energy leaving in the milk must equal the heat energy in the milk entering the pasteurizer plus or minus any heat added or taken away in the processing plant.

Heat energy leaving in milk =

initial heat energy . . . + heat energy added by pump + heat energy added in heating section - heat energy taken out in cooling section - heat energy lost to surroundings

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From these laws of conservation of mass and energy, a balance sheet for materials and for energy can be drawn up at all times for a unit operation.

These are called material balances and energy balances.

BALANCE SHEET

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Using a material balance and an energy balance, a food engineering process can be viewed overall or as a series of units. So we back to the notion of the unit operation. The unit operation can be represented by a box as shown below:

Into the box go the raw materials and energy, out of the box come the desired products, by-products, wastes and energy. The equipment within the box will enable the required changes to be made with as little waste of materials and energy as possible. In other words, the desired products are required to be maximized and the undesired by-products and wastes minimized. Control over the process is exercised by regulating the flow of energy, or of materials, or of both.

Unit Operations in Food Processing. Copyright © 1983, R. L. Earle. :: Published by NZIFST (Inc.)

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In process engineering, the prime considerations are the extent of the heating or cooling that is required and the conditions under which this must be accomplished. This specific physical process is the unit operation called heat transfer or heat exchange.

Heat transfer is a unit operation wherein the fundamental physical principle underlying it is that heat energy will be transferred spontaneously from hotter to colder entities.

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Deep-fat frying is one of the oldest unit operations used worldwide. It produces food products with a unique flavor and texture unlike any other technique. This is one of the many unit operations you will learn in this class. The mechanisms involved in the heat and mass transfer of deep-fat frying is very complex. They include heat transfer by convection and conduction; mass transfer by diffusion, convection, and capillary pressure. In addition, structural changes occur resulting in a crunchy porous network characteristic of fried foods. Oil absorption is the least understood transport phenomenon in this process.

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Let’s take some time now

to focus on the

HEAT TRANSFER

unit operation

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WHAT IS HEAT TRANSFER?

A dynamic process in which heat is transferred spontaneously from one material to another of lower temperature

PRINCIPLES OF HEAT TRANSFER

- The rate of transfer depends on the differences between the materials; the greater the temperature difference, the GREATER the rate of heat transfer

- The DRIVING FORCE in heat transfer is therefore the temperaturedifference between the heat source and the receiving material

- An increase in temperature difference results in an increase in the driving force, increasing the rate of heat transfer

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HEAT

TRANSFER

Conduction

Convection

Radiation

Mechanisms of heat transfer

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Mechanisms of heat transfer

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Two terms that you will come acrossrelated to this topic in this food processingcourse as well as food engineering courses:

THERMAL CONDUCTIVITY

THERMAL DIFFUSIVITY

A food material’s ability to transfer heat energy

The ratio of thermal conductivity to the “volumetric heat capacity” of the food (the ratio of the food

material’s ability to transfer heat to its capacity to store it

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HEAT TRANSFER APPLICATIONS

These are widespread in the food industry:

• Milk and juice pasteurization• Fruit and vegetable refrigeration• Meat cold storage/freezing• Canned foods thermal sterilization• Evaporation• Distillation• Drying

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FOURIER’S LAW

The rate of heat flow (Q/t) through a uniform materialis proportional to the area A, the temperature change (drop) ∆T, and inversely proportional to the length ofthe path flow (x).

QQQQ

Q

x

AA = cross-sectional area∆T = temp difference between endsx = distance between endsK = the material’s conductivity

Qt =

KA ∆Tx

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What is the basis of FOURIER’S LAW?

It has to do with a property of matter called

THERMAL CONDUCTIVITY (K value)

Heat always conducts from warmer objects to cooler objects. The composition of a material effects its conduction rate. If a copper rod and an iron rod are joined together end to end, and the ends placed in heat sources, the heat will conduct through the copper end more quickly than the iron end because copper has a K value of 92, whereas, iron has a K value of 11. The larger the K, the faster heat will conduct.

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What is a heat exchanger?

- Device for the transfer of heat between two fluids separated by a partition

- Partition is a heat conducting solid (i.e. metal)

- Heat exchangers are extensively used in the food industry

- Pasteurizer- Chilled water generator- Freezer- Evaporator

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Comparison of operating designs:

(1) Counterflow heat exchanger

(2) Parallel flow heat exchanger

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COUNTERFLOW HEAT EXCHANGER

HotFluid

Cold Fluid

Cold Fluid

Featuring a CLOSED-TYPE DESIGN in whichfluid streams do not come in direct contact with each other.

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PARALLEL FLOW HEAT EXCHANGER

HotFluid

Cold Fluid

Cold Fluid

The hot and cold fluid streams are separated by a flat wall or plate.

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Two Examples of Heat Exchange Equipment:

(1) Fluid Bed Dryer

(2) Spray Dryer

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Fluid bed technology is used for cooling, heating and drying of bulk solids food and dairy materials. Fluid bed heat exchange takes place by passing a gas (commonly air) through a perforated distributor plate which then flows through a layer (bed) of solids. The air performs two functions. First, the air flows through the bed of solids at a velocity sufficient to support the weight of the particles, which creates a fluidized state enabling the particles to flow. Second, the air in the fluid bed serves to cool, heat or dry the particles as it comes into direct contact with the solids material within the fluid bed chamber.

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Example:at input is wetexperimental cake batter

Collected at output:spray-dried cake batter powdered mix

In a spray dryer, liquid or fine solid material in a slurry is sprayed in the form of a fine droplet dispersion into a current of heated air. Air and solids may move in parallel or counterflow.

Drying occurs very rapidly. The dryer body is large so that the particles can settle, as they dry, without touching the walls on which they might otherwise stick. Commercial dryers can be on the order of 10 m diameter and 20 m high.

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Thank You.