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Abstract 162.1 Constraints, Context, and Reasons for Innovation , 16

2.1.1 How Innovative is the Food Industry? 162.1.2 What Are the Reasons for Innovation? , 18

2.2 Technological Trends ,' 182.2.1 Emerging Processing and Preservation Methods 182.2.2 Biotechnology ,' 19

2.3 Food Manufacturing Operations 222.3.1 What are Food Manufacturing Operations? 222.3.2 Can We Define Food Manufacturing Unit Operations? 232.3.3 Characteristic Features of Food Manufacturing Operations 23

2.4 Autornatic Control. 252.5 Advances in Tools and Concepts in Food Engineering ..':' 26

2.5.1 Tools and Concepts in Product Design 262.5.2 Tools and Concepts in Process Design 282.5.3 Tools and Concepts in Plant Operation 30

2.6 What Challenges Exist for Food EngineeringL 312.6.1 Integrating Rapid Progress in Biology into Food Engineering 312.6.2 Integrating Progress in Physico-Chemistry into Food

Engineering 312.6.3 Integrate More Mechanization in Food Engineering 322.6.4 Use a More Functional Approach in the Design of New

Products and Processes 322.6.5 Use More Mathematics to Integrate More Complexity 322.6.6 Better Integration of the Human Factor in Plant Design and

Operation 332.6.7 CanWe Integrate AH Scales? 33

References 33

CONTEN1S

G. Trystramj. l. Bimbenet

Trends In FoodEngi neeri ng

2

3. FAO/WHO. 1992. International Conference on Nutrition. Nutrition and Develop­ment-A Global Assessrnent, Food and Agriculture OrganizationIWorld Health Orga­nization, Rome, Italy.

4. Wotkei, C.E. 1998. Impacts of diet on health in NorthAmeríca, in CreatingHealthfulFood Systems: Linking Agrieulture lo Human Needs. G. F. Cornbs, Jr. and R. M.Welch, eds. Ithaca, NY: Cornell University,

5. James, C. 1998. Global review of commercialized transgenic CfOpS: 1998, Interna­tional Servicefor the Acquisition of Agri-Biotech.Applications. Brief No. 8. Ithaca,NY.

6. Leistner, L. and L.G.M. Gorris. 1995. "Food preservation by hurdle technology,Trends Food Sei. Teehnol., 6: 41-46.

7. Vega-Mercado, H. et al. 1997. Non-thermal food preservation: P111sedelectric fields,Trends Food Sei. Technol., 8: 151-157.

8. Dunn, J. et al. 1995. P111sedlight treatment of food and paekaging, Food Technol.,49(9): 95.

9. Barbosa-Cánovas, G.v. et al. 1997. Non-thermal Preservation of Foods. New York,NY: Marcel Dekker, Ine.

10. Ahvenianen, R. and E. Hurrne. 1997. Active and smart packaging fOI meeting con­sumer demands for quality and safety, FoodAddit. Contam., 14: 753-763.

11. Morris, C.E. 1998. 1998 survey of food manufacturing trends: A clear direction, FoodEng., 70(3): 77-86.

Reprinted from Reference 11, Copyright 1998,Food Engineering, Cahners Business Information, aDivisión of Reed Elsevier, lne. AH rights reserved.

-,

High Moderate Low-~ potential potential potential

Ohmic heating 10 36 54

Elcctron beam radiation 27 38 35

Gamma irradiation 33 35 32

High pressure 19 38 43

Radio frequency cooking 17 50 33

Microwave pasteurization/sterilization 37 36 27

Pulsed light 7 44 49

Pulsed electrica! field 4 36 60COz drying 18 40 42

Microwave drying 20 43 37Low-acid aseptic particulars 23 50 27Magnetic resonance imaging 22 35 43

Predictive process control 44 44 12"

TABLE 1.8Cornmercial Potential of New/Unique Process Technologies (Percent ofRespondents Familiar with Each Technologv)

Engineering and Food for the 21st Century14

• There have been few new unit operations, except extrusion cooking,membrane separations, irradiation, high-pressure treatrnents, and, in asense, manufacturing operations.

• Sorne new processes have been required to make new products (i.e.,prepared salads, new composite desserts, osmo-dehydrated products, etc.)and new operations (membranes, extrusion cooking).

G Many new techniques are used in unit operations: aseptic techniques,super critical extraction and osmotic dehydration (both being new formsof solvent extraction), ohmic heating, RF heating, water-jet cutting, asso­ciative packaging, image analysis, etc.

introduction of new technologies in the food industries during the past few decades,the number of real innovations turns out to be rather low:

Like other hnman activities in developed countries, the food industry is asked bysociety to be "environmentally correct" concerning air, solid wastes, packages,landscape, and water. The pressure on water supplies is Iikely to become a majorproblem in many countries in the coming years.

To fulfill all of the previously describéd constraints at the same time, the foodindustry has a tendency to split itself into two entities:

• First transformation industry (e.g., production of sugar, starch, oils, malr,e!c.)--close to agriculture and international raw materials markets, makingbasic products for consumers and more and more 'ingredicnts for the foodindustry.

• Second transformation industry-close lO distribution and consumers, whichmixes, assembles, and shapes ingredients to jnake complex products of variousorigins (as cereals + rneals, dairy + fruits, etc.) This evolution tends to breakthe traditionaJ organization of commodities from fiE;l"dto consumers (cereals,meat, dairy, etc.). The fast-growing activity in food ingredients is evidence ofthis trend.

On the international level, shares are bought and sold at the speed of electrons,often on the basis of short-term profits. Whole cornpanies may similarly changeowners in a very short time.

The competition in pricing and quality is increasing, mainly due to the increasingweight of distributíon chains. The increasing pres~re of retailers pushes industryto modify its way of distribution. Internet market may become an Importanrtrend.

New challenges are corning: the food 'industry has to establish and demonstrateits ability to control its production in terms of qnality, of course, but also,nowadays, more and more in terms of safety, nutritive value, and natural imageof the producto People also require more convenience and information about thefood they buy,

Evolution in thestructure of thefood industry

Respect forwater, air, andenvironment

Shareholders'power

Disrributionpower

Consumerpower

TABLE 2.1Constraints and Context of Evolution in the Food Industries

17Trends in Food Engineering

Figure 2.1 Sorne important steps for the evolution of objectives and requirements in the foodindustries.

----------~--------~~----------------------~Control scienceMechanizarion

HygieneSafetyHealth foodsFresh-like foodIncrease shelf life

Decrease caloriesDecrease saturatedfat

No trans- fatty acidReduced sal! andsugar

MorefiberNo additivesNo preservativesAntioxydativeformulation

ProductivityAdaptation ofchemicalengineering

Industrialization~~~E~n_~_gy_. __~I~1Q_n_~_'t_y__~1I~ s_a_fu_ty ~

Present and near futurePast

Evolution oi industrial steps in the food indústry

Table 2.1 presents our views of constraints to which the food industry is beingsubjected: Due to the context described here, the food industry has to manageinnovatioñ to modify and adapt its technologies. The objectives of this adaptationhave varied with time, as shown in Figure 2.1. PresentIy, the accent is placed onsafety and on an increase in quality homogeneity. But, when we consider the

2.1.1 How INNOVATlVE 15 THE fOOD INDUSTRV?l •

2.1 CONSTRAINTS, CONTEXT, AND REASONSFORINNOVATlON

Technological innovation is presented as one of the answers to the constraints in thefood industry. Examples of innovations or research, maínly in the fields of preser­vation (thermal and nonthermal techniques), manufacturing operations (operationson individual pieces), automatic control, etc., are presented. New tools and conceptsused in product and process development are described, such as product, material,and reaction engineering. Emphasis is placed on beterogeneous and compositeproducts. Finally, the authors present their ideas about challenges to the foodindustryin coming years.

The food industry is at the same time the instigator and the subject of cbangein society.When the food industry is subjected to several kinds of constraints, it hasto modify its structures, and these evolutions have an impact on its technology.

Abstract

Engineering and Food for the 21st Century16

The use of biotechnology and of biologic steps during processing has increasingimportance. A comprehensive discussion would be necessary to describe this aspect.Sorne of this inforrnation is reported in Reference 2. Table 2.4 summarizes a few

2.2.2 BIOTECHNOLOGY

Also, in the heat processing of food, major improvements can be provided usinga combination of classical heating methods (convection in-air or Iiquid) and newtechnologies as presented in brief in Table 2.3. The way to combine these technol- .ogies is not well established at present. Nevertheless, numerous applications ateavailable,

An interesting point to discuss is the aseptic processing principle. It must beindicated here that it is not realIy a new unit operation or principIe of processing,but it is a new set of technologies that permit work to take place in a safe andhygienic climate. The next questiort for such processes that researchers and engineershave to face concems process optimization. But the introduction of the hygiene pointof view probably will be very important to the future of food industries (see Figure2.1).

Figure 2.2 Factors inñuencing the success of new technologies at the industrial level.

LegislationConsumerScientificcommunity

Trade unions

Acceptance

InvestmentcostOperation costFlexibilityReliabilitySafety

Equipment

MicrobiblogyToxicologyAllergyParticulates

19

Concurrenttechnologies

Trends in Food Engineering

An exhaustive presentation of emerging methods for the processing of food productsis quite difficult. In the case of preservation, sorne points are summarized in Table2.2. In sorne cases, technologies have already been transferred to industry,The mainidea for such research is to process food without heat. In fact, in many of thesetechnologies, some heating occurs during processing. Except in sorne specific appli­cations that are highlighted in Table 2.2, it becomes obvious that a combination oftechnologies is preferred.

2.2.1 EMERGING PROCESSING AND PRESERVATIONMETHODS

2.2 TECHNOlOGICAl TRENOS

Another important point is the acceptance of the new technology by the user. Itis obvious that this mechanism of acceptance is not easy to implement, Figure 2.2represents different points that have to be considered during the evaluation of a newtechnology for industrial purposes.'

• Allhough heat is fue most common method for transformation, sanitatíon,and preservation, it is well known today that the eonsequences of heatingare not neeessarily good for the producto Therefore, nonthermal processingis an important objective. On the other hand, the ability to perform aecurateseparations of biomolecules becomes more and more important. The con­sequences of such progress are the lengthening of preservation time and anincrease in the consumer's perception of the food as being "natural."

• Another driving force for innovation is probably fue attainment of newproperties (texture or aroma, for exarnple), which may require new tech­nologies. The design of new products is a matter of competitiveness forindustry. In such new products, safety considerations become very impor­tant (Figure 2.1).

• The competition .between companies and the relative ease in fue designof "me-too" products imply firms' increasing focus on technologiesinvolved in the process.

• Innovation is evidently the direct result oí research and developmentwithin the firmo But it is also the consequence of research made elsewhere.Transfer from one industrial domain to another is a frequent path ofinnovation. Screw extrusion was used in the plastics industry before beingtransferred to the food industry to be utilized in extrusion cooking. Today,one of fue most promising directions of research and inuovation is cer­tainly derived from rapid progress made in the field of biology,

A set, probably not exhaustive, of reasons for innovation eonsists of the following:-,

2.1.2 WHAT ARE THE REASONS FOR INNOVATION?

This shows that most of fue existing teclmologies have been in use for a long time;there is more progressive evolution than striking innovation.

Engineering and Food for the 21st Century18

,t'.):.~

::;1(1):::Jo,<J>s:"TIge,m:J~.:J

~.:::J(JQ

Pieces of product are innnersed in oil _¿.Drying,baking, frying andal a high ternperature (180~C). extraction of oil

Precooked prepared meals Tor coldstorage

The most used method. The combinatlon of techniques is iuade to ímprove heat trunsfer.The tnain ways lo improve heat uansfer are te increaseCollveX:UÜI1(better heat transfercoefficicnt), introduce controlled radiation und .combine steani injection wíih un exchanger.... . . .

Mear, cereal products, fruits,vegetablcs, and fat productsEvery product

~

Fruits, meat, fish products, andvegetables

Thin product pieces

Pumpable products

Liquid or pieces of producís:application available for in­

package productsPuinpable products, even ifparticles are present

Niunerous applicatlons

Vacuum permits the reduction of Every kind of heat Lower temperaturetemperature, treauneut

Heating of tightly packaged products, Cooking amipastcurizution Quality, safety and less losses

Increase of transfer coefficient;controlof impregnation or drying1S possible through operatingconditionsIncrease of transfer coefficient; fastdryíng

Dehydration, soaking,salting, and pickling

walls ternperature

Baking, drying and roasting High-intensity drying;high heatingrate

Excellent control of exchunger

Direct in situ heating

Heating, pasteurizationElectric current sent in exchangerwalls.

-Superheatedsteam heats the productlike a hot gas.Pieces of"product are immersed in aconcentruted solution; heated or '001heated.

Electric current is directly injected in Heating, pasteurizationthe pipe; Joule effect, also in piecesof products, if present,

In situ heat generation Heating and íhawing Direct in situ heating-oftencombined with air

Infrared radiation heats the surfaces- Heating, surface treatment, Funetíon of optical properties ofsmall penetration depth. and pasteurization food

°Reat processingimprovement

cooking"Sous-vide"

Under vacuum

Immersion frying

Immersíon

Indirect ohmicheating

Superheated steam

Direct ohmicheating

Microwave/highfrequency

Infrared

ProductsPrincipie Applications Advantages

lAStE 2.3New Principies of Heat lreatments

Sterilízatíon, bu! theprinciple is not exactIyknown

m:::l~.:::J(1)(1):::!.:::J

(JQ

'":::Jo,"TIOOo,

Q'....::¡­(1)

N~~()(1)

;ae-<

NQ

Disinfection, sterilizationVerystrong and fast light pulsations;effect of high peak power andbroad spectrum of flash; realprincipIe unknownHigh-density pulsed magnetic fieldprovokes a dramatic decrease ofmicroorganisms.

A high-electric field is applied. If thevalueis higher than acritica! value,pores appear in the cellruernbranes. The deterioration ofmembranes is irreversible.

Purnpable foods; packages; in package possible;water processiug

Nontherrnal processing;different effects onparameters such as pH,ternperature, etc.;Inactivation al lowerternperature, alternauvefor pasteurizationSurface inactivation-alltypes of mícroorganismsare inactivated (sporesand viruses 'included)

Number of studies is stilltoo low

Effect on spores is unknown-only pumpableproducts

Low-temperature process Packaged product (in batch)-may becontinuous for líquids

Inactivation ofmícroorganísms, thawing;Ircezing; diffusion ofsolutions (impregnation);and protein denaturation

Saniuuicn, extraction

Increase of pressure (until 8000bars)-lhe stress applied modífiesthe behavior of microorganisms,proíeins, etc.

Pulsedmagnetícfield

Pu!sedlight

Pulsedelectricfield

ProductsHighpressure

\

AdvantagesApplicatlons (functions)Principie

lABLE 2.2New Nonthermal Principies of Preservation lreatmenfs

/

These manufacturing operations have other fearures that justify special interest,Many of them treat products on open conveyors or in open vesse1sor equipment,and they include human handling or the close proximity of humans. This means thathygienic questions are often critica1 for such operations and justify the use ofmicrobiological control of the atmosphere. Clean rooms or aerobic protection ofequipment must be employed.

In many instances, heterogeneity is part of product quality, especially when acomposite object consists, for example, of the combination of soft and crispy layers.The problem is then to control the transfer of wateriand/orother molecules) betweenthese layers.

In matters of quality, each piece must fulfill certain requirements (weight, com­position, contamination, etc.), whereas bulk products are sold by total weight andaverage characteristics with certain variation allowable among samples.

Many of these operations are results of the industrializationof manual operationsdeveloped in kitchens. Mechanization may be difficult due to the complex nature of

2.3.3 CHARACTERISTICFEATURESOF FOOD MAI'\IUFACTURtNG

OPERATlONS

This means that the most interesting and original of these unit operations consistsof shaping, separation, and assembly, including packaging.

.. Many heat and mass transfer operations (can sterilization and drying) arebased 00 principIes that do not differ from the principIes of opera:tionsperformed on bulk products, and they are classically studied,

• Tbe same situation exists for reaetions in food objects; their rates aredetermined by heat andJormass transfer and/or by reactions kinetics-e-allclassical concepts, .

• Transportationof objects isnot specific to the food industry if these objectsare packages or packaged products; however, a specíficity exists if itconcems bare food objects, beeause problems of stickiness, hygiene, anddeformation may be encountered if the producís are semisolids.

We can tentatively make a list of such unit operations (Table 2.5) as follows:

2.3.2 CAN WE DEFINE FOOD MANUFACTURING UNIT'"OPERATlONS?

considering objects individually or starting from a bulk product to inake suchindividual objects. These objects are generally "large," but their size .is AQ~merelevant eriterion. If fruits are peeled by a knife, they receive an individual treatmeüt,and the position of each of them is determined; this .maybe considered a manufac­turing operation.When potatoes are peeled by abrasion, the position of each of themis not controlled; there is random treatment 00 a bulk product, Similarly, the colorsorting of coffee granules by high-velocity optical machines considers each grainindividually, and this operation can be considered food manufacturing.

23Trends in Food Engineering

We have proposed" to define a new category of unit operations of food engineeringthat we could call food manufacturing operations. It could be defined as operations

2.3.1 WHAT ARE FOOD MANUFACTURING OPERATIONS?

Infact,most products sold to consumers (excludingmost ingredients sent to secondarytransformation) in industrial countries for many years have no longer been cornmer­cialized in bulk, Products are packaged, and often shaped, either traditionally (e.g.,bread, sausages, cheeses, and biscuits) or in new shapes (e.g., fish fingers and frozenhamburgers). Furthermore, people consume more and more composite objects suchas two-layer dessert creams, multilayer cakes, ice crearos in eones, pizzas, industrialsandwiches, and prepared dishes. All of this means that growing parts of food plantsare devoted to fomúng, assembling, conveying,and otherwiseprocessing suchobjects.

1. Treatment ofproduct in bulk, mainly liquids or solid particles, correspond­ing to the classical unit operations of chemical and food engineering(centrifugation, heatinglcooling in exchangers, distillation, milling, etc.)

2. Treatments on "objects," i.e., products like pizzas, cakes, pieces of meator fish, and packaged products (cans, bottles, etc.); examples of suchoperations include the deposition of fruits on a pie, cutting, molding,assembling of severa1parts, packaging, etc.

A visit to almost any food plant will show two types of operations:

2.3 FOOD MANUFACTURING OPERATlONS

directions of progress in bioteehnology that, in our opinion, offer important contrí­butions to the evolutionof food industries.When more generally speakingofbiology,nutrition must also be quoted as becoming a major incentive for the creation of newproducts.

Other technological evolutions have been described aboye. We now present asseparate topics two specífic trends: food manufacturing operations and automaticcontroL

for measuring pathogens, unwanted xenobiotic, etc.

Specific kits and atIine sensors become available.toolsNew analytical

Tbe cell factory ,'" The use of microorganisms is a way to "do things that can more rapidly lead tonew producís." Bioreaction engíneeríng (including enzymatic engineering) is animportant area of progress.

Probably, this is the major arca of interest, with the design of new specífic probes

Genetic and agronomical engineering for agricultural products permits the designof new raw rnaterials. The incidence on processing is not established.

Processing onthe field

lABLE ~.4Examples of Perspectives of Biotechnology Application for Innovation inFood Industries

Engineering and Food for the 21st Century22

Figure 2.3 PrincipIe of sensor development for food process control applicatíons.

principies

1t ís well recognized today that control science is one of the important avenues forprogress in fue food industries," A review of applications and the potentíal of controlscience in the food industries has been presented.' The main points and ideas areas follows. In parallel with heat and mass fluxes, which ate classic for food engineers,the complexity of flow sheets implies that fluxes of informati:on are essential aiJ;dmust be taken into account. As it may appear from Figure 2.1, the new objectivesof production imply a necessary evolution frOIDmechanization (important for 'P(Ó~

ductivity criteria) to control (important for quality and safety criteria). Withotjtcontrol, many processes cannot work.

The consequence is that numerous studies have proposed fue 'introduotion ofnew sensors. Figure 2.3 proposes a set of available methods for sensor designo It isimportant to remark that most of the progress today is being made using classical(simple-ro-use) sensors in combination with computer-based applications.

The direction of algorithm design for control purposes is still under activedevelopment. Nevertheless, an important gap remains between the level of laboratory

'J

2.4 AUTOMATIC CONTROL

require robotization (in the sense of programmable mechanization), This may 1imitour interest in investments in mechanization, robotization, and automation.

To all of these specifics may be added the fact that fuese operations so far havenot been the objects of education and academic research commensurate with fheirimportance in industrial investments and with the concerns of food plants operators,One important exception is packaging, which has received SOrne attention in recentdecades. This deficiency of research, however, has been aIleviated by the transferof technology from mechanical industries (products, robotization), These consider­ations raise our awareness of the need to give mote importance to the topic ofmechanics in the food industry.

Trends in Food Engineering

many products (thick liquids, pastes, or semisolids=-fragíle, deformable, oftensticky) ro fue composite structure of many of them and to their complicated shapesor dispositions. For example, think of how we could mechanize the deposition offour anchovies on a pizza, In such operations, the mechanical design of the machinemust be related to a knowledge of the mechanical behavior of the product.

Even then, repetitive mechanization, which requires constant human supervision,is real automation and is difficult to realize, because it supposes SOrne real-timemeasurements, The weight of pieces is fairly easy to measure (as is .color), but thedetermination of shape may require image analysis techniques. Furthermore, auto­mating the control of plants that inelude such operations is very different from thecase ofbulk products; it supposes the control of waiting lines, of flow rates measuredin objects per minute, etc., which are all techniques that have been more highlydeveloped in mechanical industries than in food processing.

In many cases, the same plant has to produce a succession of several batches ofproducts in the same day, which means that flexibility is necessary, and this may

Cheese, yogurt, dry sausageReactions Biological and enzymatic

Everything

Bread, biscuits, meatPreservesMeat, breadMeatHam, cheeseHam, cheese, sausages

'Iransportaiion Conveying

Heat and mass Cookingtransfer Canning

RoastingCooling, freezingSaltingDrying

Dosing, depositíon, powdering,coating

ArrangementClosing, sealingLabelingWrapping, cartoning

• of liquids• of pasty products• of powders and partic1esOn pizzas, cakes, prepared meals, allcornposite products

Candies, cookies in boxesBcttles, cansOn bottles, cans, etc.Bottles, cans, etc.

Assembling Filling

Mear carcas sesMear, fishFruitsFruits, vegetables, coffee grains

Separation DisassemblíngCuttingPeelingSorting

Bread, biscuirs, sugarBiscuits, ham, sugarPasta

Formífig Molding""'.Extrusion

Lamination

Example of productsPrincipie Unit operation

TABLI~ z.sExamples of Food Manufaduring Unit Operations

Engineering and Food for the 21st Century24

networks

(linquistc)

during processing

Trends

biochemical reactions and the evolution of important factors such as temperature,efficient

IN

for

the form 01'used to determine water content

engineering will have to be assimilated in the processesthe

used to

control?Will

transfer of vn,"''''¡t'',in?' and technology from other sectors. In addition to the fieldsdescribed 01' progress

this field will comeMost of the advances

used moreommendations related to hygiene,traceability, consumers, has'~"f',rll,,~j- batches.

31

the lineofrequent. At upper level, flux management andoperation makes this management more critical. The connection between sales, salesforecasts, materials and other L"-<./...,A."~U, pn)QUICnOn,has become factor

2.5.3

the

account as as in isof a "clean process," by which we mean that the process is designed to minirnizeflows of and thus ...."'rinr-H-.n

designs.The

Engineering and Food for the 21st Century30

7.

5.

3. Bimbenet 1. 1. and G. Trystram. 1993. "Evolution du Génie Industriel Alirnentaire,"alim. 1-12):

Preservation Technique," Colloque "La conservation de demain," Pessac, France,User1.

with machine rather than replacing him?It that

2.6.5 USE MORE MAIHEMATICS 10 INTEGRATE MORE COMPLEXITV

IN OfUSE MORE FUNCTIONAl

NEW PROOUCTS ANO PROCESSES

MECHANIZAIION IN

pbysico-chemical

very small scales.

profiles in products during and after processing, Will this method be

for