30 November 2011

Quality on the Edge: Quality from a Manufacturing Perspective

Quality on the Edge: Quality from a Manufacturing Perspective

E. Wijs1 and W.B.C. de Heij2
2 ATO b.v., NL, wouter.deheij@wur.nl

         Convenience        is  booming      business.    Some     thirty  years   ago,   first  attempts    in
providing easy to handle and ready-to-eat foods to consumers were reported. During the
last   decade     developments       have    been    fast  and   major     progress    has   been    made    in
maintaining quality and safety of the fresh cut produce. And in that last remark not only
the progress is indicated, but the major problems as well: what is quality, what is safe and
what is fresh?
         The     chain   concept    and   its  benefits   are   built  upon    trust  in  predecessors     and
successors in that chain. Entire food supply chains and networks are built on that concept.
For the fresh cut produce that is not different. Trust is fine, but… commercial companies
are no fools. They need some proof of trustworthiness, some proof of quality, some proof
of safety, some proof of freshness. So, even in the concept of chains and networks, some
product     properties    have   to  be   measured     and   some    indication    of  quality,   safety   and
freshness has to be provided.
         About 60 companies are producing fresh cut, washed and packed vegetables in the
Netherlands,   most   companies   produces   there   products   for   local   hospitals,   restaurants,
catering   services   and   food   services.   Based   on   annual   turn   over,   in   Holland   the   top   6
products are mainly prepared for the supermarkets (“retails”). Sales of fresh cut produce
in the Netherlands have increased from the early nineties from €100 million to about €300
million nowadays.       Roughly 80% of these sales are realised in the retail sector.
         In this paper, an overview will be presented of aspects important to commercial
application of fresh cut horticultural and agricultural produce, how to acquire the proper
information, and how (and to what extent) to trust your partner. An integrated view on
fruit and vegetable quality, applicable throughout the chain will certainly make life and
business easier.

         VEZET’s        origins   lie  in  a  factory   built  in   1914   for   salted  vegetables     by   K.
Wagenaar. The “Vereenigde Zuurkoolfabrikanten in Nederland” the ”N.V. tot Exploitatie
van    Zuurkoolfabrieken“        existed    in  1956,   whose     objective   was    the  manufacture      and
handling of sauerkraut, salted vegetables and other food. VEZET began to look for ways
of expanding the range with products other than the well-known and trusted sauerkraut at
the   beginning of   the seventies, with the help of Albert Heijn (supermarket - AHOLD).
This   was   found   in   "vegetables,   which   were   made   so   ready   for   consumption   that   the
consumer   only   had   to   prepare   them".   In   short,   this   product   was   called   "ready-to-cook
vegetables".   This   early   period   was   marked   with   discussions   about   traditional   products,
such as different sorts of cabbage, endives, carrots, leeks, soup vegetables etc. The name
was   changed   in   1973   to   "Vereenigde   Zuurkoolbedrijven   B.V.",   quickly   abbreviated   to
"the     V.Z.",     which     gave     rise   to   the    name     VEZET.        The    name      Vereenigde
Zuurkoolbedrijven B.V. was also officially changed to "VEZET B.V." at the beginning of
1998. The factory underwent a large-scale expansion and adaptation in 1996-1999. Many
ultra-modern       provisions   were   introduced   during   this   reconstruction   to      initiate  further
         Now, in the year 2002, VEZET is one of Holland’s largest vegetable processing
companies and is the market leader in freshly cut, ready-to-cook vegetables. This modern
vegetable      cutting   company      has   a  range    of  about    250   different    products    (different
mixtures,   packages   and   sizes).   The   product   range   includes   salads   and   raw   vegetables,
mixed vegetables and soup vegetables. Traditional cooking vegetables are also still a part
of the total product range. Besides regular products a growing range of organically grown

Proc. Int. Conf. Quality in Chains
Eds. Tijskens & Vollebregt                                                                                   29
Acta Hort. 604, ISHS 2003

products   has   entered   the   market   as   well.   These   products   are   owned   and   prepared   in
accordance with the Skal guidelines.
         The total annual production is about 30,000 tons of fresh vegetables. About 450
people (permanent and flexible) are currently employed at VEZET. Since October 1973
VEZET has been the exclusive supplier of ready-to-cook vegetables to Albert Heijn B.V..
The existing premises were expanded several times due to the rapid growth in this market
during     the  nineties   An    other   portion   of  the   produced     goods    is  sold  as  vegetable
intermediates      in  bulk   to  industrial   customers    and   for  the   food   service   market    (e.g.
restaurant chains and food services). These customers process the intermediates into for
example soups, salads, pizzas, cheese spreads and mixed vegetables. Since 1997 ready-to-
cook vegetables are also supplied to supermarket organisations abroad.

         Since quality of perishable produce is a rather subjective attribute, you know all
more about that, it is very difficult to develop viewpoints, preferably measurable, that can
be shared by the actor in the chain. A system that does work in practice is the so-called
manufacturing approach (Sloof et al 1996). It is once defined what can be understood
by   quality   in   measurable   attributes,   and   these   findings   are   laid   down   in   the   product
specifications. So, whenever a batch of produce does comply with the specifications, that
batch is acceptable for the chain. The danger of this system arises when the specifications
no longer reflect the preferences of the consumers / buyers. This happened a few years
ago with tomatoes produced for Germany. No one in the chain, not even the companies
where the tomatoes were supplied to, had anticipated the fierce and sudden rejection of
the   quality   of  the  produced     tomatoes.    So,  when    applying   this   simple   and   appealing
system, somebody has to watch continuously the changing trends and preferences of the
         When      including   constantly    the   preferences    of  the  market,    we   gradually    shift
towards the User based approach (Sloof et al 1996). In this system, the psychology on
consumers, his preferences and his constantly changing buying behaviour is an essential
part.   Although   this   system   reflects   more   accurately   the   actual   situations,   for   practical
purposes it is at the moment quite out of reach for commercial companies. As a matter of
fact, as far as I understood, for scientific purposes as well, a very popular and workable
intermediate between the two systems is the system of keeping quality.
         Among   the   factors   that   affect   the   way   consumers   understand   concepts   of   food
quality and safety, the multiple food retailers, or supermarkets, are significant. As more
food produce is moved through a reducing number of supermarket chains the power of
supermarkets   over   food   supply businesses   grows. What   consumers   believe to stand for
quality has become more closely aligned to the supermarkets’ own definitions of quality,
of which food safety is a part. Consequently, as greater numbers of consumers shop in
supermarkets,   suppliers   are   forced   to   adjust   their   own   understanding   of   quality   in   line
with that of supermarkets if they are to stay in business (Jongen, 2002). We come back to
keeping quality as applied by commercial companies in the sector of cutting vegetables in
the next section.

         Keeping quality has been defined as the time a commodity remains acceptable far
a large group of consumer (Tijskens et al. 1996). Problems arise immediately from this
definition: what is a large group of consumers? What is still acceptable? Is it the always
the   same   quality  attribute that is limiting? All three questions can (and will) affect the
eventual   outcome   of   quality   assessment   and   acceptability   further   down   the   chain.   As
already mentioned, the chain is largely built upon thrust among the actors in a chain. The
chains actors nevertheless need a clear description of what to measure (and to provide) to
be a reliable partner.
         Bacterial load (CFU) is largely accepted as the prime indication of freshness and
keeping quality. So, washing the delivered commodities is a very central process in the


preparation of cut vegetables. There are however, indications that bacterial load is not at
all   so   tightly   connected   to   the   keeping   quality   of   the   produce.   And   during   continuous
washing, the water itself tends to get a high bacterial load. In practice the bacterial load of
leafy    vegetables     can   be  reduced     by  roughly    one    log-cycle,   with   (USA)     or   without
(Holland)   the   legal   permission   to   use   chlorinated   washing   water.   On   top   of   that,   by
excessive washing in large tanks produce can pick up as much as 20% of their weight by
sucking in water.   Polluted   water,   Chlorinated   water!? What   is the effect of this on the
keeping quality?
         What      else   do   we    have   as   an   indication    of   quality    and   keeping     quality?
Appearance!        But   how    to   express    appearance      in  a   numerical     way    to  be   able   to
communicate with   the   partners   in the   chain? What to measure? Bacterial spots? Slimy
patches? Then we are already too late. Wilting? Picking up that amount of water surely is
an adequate remedy to that. Does it last? Maybe the technology developed during the last
couple of years at the ATB (e.g. Herppich 2000) can provide some useful concepts. But
what is needed above all are simple measuring techniques. Freshness of produce? In the
USA the term freshness may be used as long as the produce is respiring. But that is not
what is meant by freshness in the vegetable cutting and packaging business or even the
freshness definition as being used by consumers.
         Price? Expensive products will have a better quality! But does it? Always? Price
mechanisms depend on more factors then careful production. And it certainly cuts down
your profits. Higher quality can be paid a higher price. That is not impossible. People in
the   western   world   are   most   of   the   time   willing   to   pay   a   higher   price   for   quality   and
convenience. That is what the cutting business is all about. But again, how to evaluate
quality?   Instead   of   being   a   solution   to   the   problem,   economic   factors   seem   to   be   the
initiator of the problem. What can be done, and what is done on a regular basis, is making
price covenants with suppliers and retailers, based on trust and previous experience.
         So,    all  these    attributes   and    product    properties,    however      important     for  the
evaluation of the quality for fruits and vegetables, can hardly be measured by objective
means, and one is in practice stuck with the good visual and manual inspection of samples
of batches of produce. And that is not too reliable to communicate up or down the supply
chain. A great research opportunity!

         VEZET puts quality high on its list of priorities. Quality is important in the whole
chain   from   the raw   materials to the final product as being seen (Figure 1), bought and
eaten   by   consumers.   VEZET   is   therefore   very   closely   involved   in   the   cultivation   of
vegetables and has been working for many years with growers, who follow a controlled
cultivation   programme.   This   is   now   being   extended   to   a   Eurep-GAP   (Eurep   =   Euro-
retailer produce working group, GAP= Good Agricultural Practice) certified cultivation.
Quality     is  also  an   important    item   during    the  production     process.    During    the  whole
production process from the incoming raw materials to the outgoing final products daily
checks are therefore made to guarantee the (keeping) quality the client expects. Tracking
and   tracing   is   a   subject   that   is   receiving   increasing   attention   since   the   whole   chain   is
important in relation to keeping quality and clients wants to know more about what has
happened to a product and where it has gone to. Everything is becoming clearer and the
chain   has   become   more   transparent   with   the   increased   implementation   of   automation
methods. It becomes possible to take action in the chain at the right moment to guarantee
the quality and safety of the final product. Certification of the production process and the
methods      of  working,     play   an   important    role   as  well.   VEZET      is  therefore    certified
according to EDI, BRC and SKAL regulations. It has the HACCP-certificate since 1998.
With   these   certifications   our   costumers   are   ensured   that   a   minimum   set   of   (hygienic)
procedures have been implemented.
         VEZET,        however,     continuously      tries   to  improve     the   product     quality.   The
laboratory      plays   an   important     role  in   this.  Continual     checks    and   assessments      are
conducted in the laboratory, starting from the delivery of raw materials. A produce that

does not comply with the specifications, is returned to the supplier. Samples are regularly
taken during the production process as well, so that the quality is guaranteed up to the end
of the production process. For example metal detectors are used, to check each individual
product package. Other attributes that are being monitored regularly are: microbial count
(bacterial load), optical quality and the smell / odour of the product. Besides the benefits
of   having   an   own   specialised   laboratory,   both   the   product   and   process   are   regularly
innovated.     A   good    way   to  innovate    is   to  work  together   with   skilled   scientists   from
research institutes like ATO. These scientists are able to translate fundamental knowledge
to   practical   applications    and   vice   versa.   An   example     of  such   a  collaboration     is  the
research project involving twelve companies, the branch organisation (Frugi Venta) and
ATO. This project focuses on the efficiency of the (submerged) washing processing and
the relation of this process with the overall product quality.

         As   the   reader   of   this   articles   probably   noticed   right   now,   more   questions   arose
than    answers    were    provided.    The   world,    hence    also  the  fresh   produced     companies,
changes rapidly due to economical, political but above all consumer demands. Based on
the    wish    of   these   modern      emancipated      consumers,      new    (European)      legislations,
commercial companies have to, and will improve their processes and the quality of their
products.   As   a   short   conclusive   summary  and   with   the   intention to tickle   the   reader,   a
short list of research needs from the perspective of the vegetable fresh cut industries is
provided below.

From a product point of view:
        •   Thorough       overview     for  all   single   and   mixed     produced     products    will   be
            o     What      are   essential    attributes    (colour,    smell,   microbial     load?)    that
                  determine the product quality and the keeping quality?
            o     Which      attribute   will  drop   most    probable    below    a  certain   threshold   or
                  quality acceptance limit?
            o     What is the (main) mechanism of deterioration?
            o     Prediction   of   keeping  quality  and   shelf-life as   a   function   of the   relevant
                  external   factors:   temperature,   moisture   content,   initial   quality of the raw
                  material etc.
        •   A Keeping Quality knowledge management system to store and share product
            specific information.

From a process and technology point of view:
        •   Fundamental   research   to   the   effects   of   (industrial)   processes   on   the   overall
            product      quality.   Hence,    how    does    the   keeping    quality    interact   with   the
            processes used in the industry?
            o     What   is   the   optimal   washing   method   (type,   temperature,   residence   time
                   etc.) to produce an optimum (keeping) quality?
            o     What is the optimal method to dry washed products, what are the optimal
                   drying conditions?
            o     What      is  the   optimal     product    specific   packaging      material,    modified
                   atmosphere (MAP) and storage temperature?
        •   Mathematical   modelling   of   most   important   process   steps   (cutting,   washing,
            drying). Process oriented modelling can be used to support the design of and
            adjustments   to   equipment   (e.g.   what   is   the   effect   of   implementing   additional
            cooling into washing equipment).
        •   Further implementation of measuring and controlling systems in all processing
            steps    to  enhance     the  functionality     (flexibility  of   process    lines),  to  reduce
            processing costs and to improve product quality.
        •   Development        of   product    quality   probes   /  sensors    /  monitoring    systems     to


independently quantify the essential attributes of both the raw material and the
            final product. The system or method must be accepted by all actors in the chain.

From chain point of view:
        •    Optimisation and further collaboration between all actors in the chain:
            o     Research   to   the   demands   and   preferences   of   consumers.   Based   on   the
                  outcome of this research, an accepted definition of product specific quality
                  may be introduced based on relevant attributes. The sector needs a better
                  insight   of   food   quality   and   safety   and   they   have   to   come   to   terms   with
                  consumers’ changing perceptions of food quality and increasing awareness
                  of food safety issues.
            o     How   to   increase   the   trust   between   the actors   in   the   chain   and   provide   a
                  sustainable relations vertically between the different suppliers? The focus
                  will   be   on   food   quality   through   the   entire   food   chain   and   the   consumer
                  demands in stead of short term profits of individual companies inside that
                  chain (Van Kooten, 2002).
            o     Transparency        of  the   chain    by   further   implementation       of   knowledge
                  management systems           (tracking-and-tracing). Modern consumers want to
                  know   what   the   origin   of   their   vegetables   is   and   how   the   food   is   being
                  processed. Greater involvement of the public will decide how to manage
                  and   regulate   technology   innovation   (e.g.   averse   of   chlorination,   with   or
                  without additives etc.).

Literature Cited
Sloof   M.,   Tijskens   L.M.M.,   Wilkinson   E.C.   (1996):   Concepts for   modelling quality of
    perishable products. Trends in Food Science & technology, 7, 165-171
Tijskens L.M.M., Polderdijk J.J. (1996): A generic model for keeping quality of vegetable
    produce during storage and distribution. Agric. Systems 51, 431-452
Herppich W.B., Hemple H, Geyre, M (2000): Carrot water relations during postharvest :
    effects     on   internal   and   external    product     quality.   Proceedings      2    International
    conference  An   integrated   view   on   fruit   and   vegetable   quality   p.   64-72.Technomic
    Publ. Co. USA.
Kooten O. van, (2002): Transparante ketens: een kwestie van vertrouwen ! (transparent
    chains: a matter of trust), ISBN 90.5059.151.5, Den Haag.
Jongen, W. (ed.), (2002): Fruit and vegetable processing – improving quality Woodhead
    Publishing Ltd, Cambridge


Table 1. Difference between manufacturing and user based approach.
 Manufacturing approach                                 User-based or perceived quality
 oriented to non-perishables                            oriented to perishables
 only objectively measured properties                   Subjective aspect of consumer evaluation
                                                       (appearance, colour, …)
 Formalised into technical specifications               Perspective of the consumer
 quality is replaced by ‘meeting specs’                 ‘fitness for use’
 substitute for consumer preference
 Perspective of producer


                                  Keeping Quality = “Quality-in-chains”

   Grower                         VEZET b.v.                   DC            Supermarket           Consumer

 Cultivar                           (See Figure 3)        Keeping Quality   Refrigeration (type) Refrigeration
 Green house vs    Wholesale                              Temperature/time  Keeping Quality      Temperature/time
   field grown                                            Handling          Temperature/time     Transport to home
 Dutch vs EU       Grade                                                    Handling             Handling
   vs …            Keeping Quality                                                               Receipt
 Classical vs      Temperature/time

                               Responsibility / influence of actors in the chain

Fig. 1. Overview of the vegetable chain.


Fig.   2.   Examples   of   products   being   produced.   Mixed   vegetables   (left   above);   cooking
                    vegetables   (right   above),   salad   bowls   (left   below),   food   service   market   (right

                                                                                          VEZET b.v.VEZET b.v.

      Raw materialRaw material                                        ProcessingProcessing                                    Storage of productStorage of product                      transporttransport

  Temperature/timeTemperature/time                  Temperature production facilityTemperature production facility                 HumidityHumidity                                HumidityHumidity
  Packaging (crate)Packaging (crate)                Humidity production facilityHumidity production facility                       Temperature/timeTemperature/time                Temperature/timeTemperature/time
  Relative humidityRelative humidity                Certification (e.g. HACCP)Certification (e.g. HACCP)                           Packaging (crate)Packaging (crate)              HandlingHandling
  CultivarCultivar                                  Training of employeesTraining of employees                                     HandlingHandling                                DistanceDistance

          CuttingCutting                   MixingMixing                    WashingWashing                               DryingDrying                      MixingMixing                  PackagingPackaging

  Cutting methodCutting method                                     Submerged vs sprayingSubmerged vs spraying    Method (e.g. centrifuge)Method (e.g. centrifuge)                  Modified atmosphereModified atmosphere
  Particle sizeParticle size                                       Residence time productResidence time product  RPM vs timeRPM vs time                                            MaterialMaterial
  SprayingSpraying                                                 Temperature waterTemperature water            LoadLoad                                                          SizeSize
  CleaningCleaning                                                 Quality of waterQuality of water                                                                                Air/product ratioAir/product ratio
                                                                   Water refresh rateWater refresh rate                                                                            PressurePressure

                   Control of product quality = management, technicians, laboratory, purchase, …Control of product quality = management, technicians, laboratory, purchase, …

Fig. 3. Vegetable processing chain of Vezet. Key-words mentioned influences the overall
                    (keeping) quality of the produce.

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