A Tale of Three Pads … 

Once upon a time there was a pad.  It was the only pad available.  It was made of paper, sodium metabisulfite and little else. It was the mid 1980s …

The international table grapes industry was growing fast … there were a lot boxes of table grapes been shipped from far remote places to the developed world. In the beginning only very high quality grapes could make it after 3 to 6 weeks of transportation and storage.

But more and more growers/exporters got into the business.  And millions more of boxes of table grapes were now using SO2 pads.  The same pad, the one we mentioned before, the traditional SO2 paper pad.  And a lot of grapes began to go bad, before, on or after arrival.

First, some exporters began to ship grapes that were not so good and strong; but second, handling conditions during transportation and storage (temperature and humidity) deteriorated because due to volume and limited cold storage facilities.   

Then in the beginning of 1990 and new pad came along ... Grapetek, a South African Company invented the laminated plastic SO2 pad: Uvasys. This was an innovative SO2 pad developed with three clear objectives:

  • To reduce the levels of SO2 concentration inside the box when a paper pad was used;
  • To maintain stable emissions and concentration in the box which were very highly unstable in the paper pad;
  • To extend the duration of the pad which was at the best; 60 days in the traditional paper pad under optimal conditions of storage and transportation.

While Uvasys improved upon the first generation of SO2 pads, it failed to succeed in two important areas.

 Uvasys did reduce SO2 emissions. However it lowered emissions so aggressively that in many cases it failed to stop the development of Botrytis, which by the way is the main purpose of the SO2 pads to control to.

Uvasys also extended the duration of the pad up to 180 days. This duration actually lasted beyond so far, the commercial viability of table grapes and their shelf life.

By 2005, the new millennium was underway and with a new era of globalization. The volume of table grapes shipped around the world has grown to an astounding 400 million cartons a year. And a new generation of pad, PROTEKU Laminated and Polypropylene pads, entered and revolutionized the market.

PROTEKU pads were developed as a balanced solution to control the development of Botrytis cinerea during transportation and storage of table grapes. Its signature was not too little, not too much approach.  PROTEKU pads provide all the benefits associated with previous generation of pads, but without any of its shortfalls.


-          Provide SO2 concentration inside the box that really keep Botrytis at bay and maintains stems green and fresh:

-          Maintain emission stability overtime preventing berry damage, particularly bleaching, when cold chain breaks occur;

-          Last just as long as the grapes are commercially viable, i.e. no more than 120 days.


Let us then compare a graphic developed by INFRUTA, manufacture of PROTEKU Laminated pads, with real data. The following graph shows the behavior of PROTEKU Laminated pad in terms of SO2 concentration inside the box over time versus traditional and Uvasys pads.

Why SO2 pads are similar (in functioning) but different? It is all about Structure … The answer is: because the way they are built and the materials they are built with.

The traditional SO2 paper pads were built with sodium metabisulfite as active ingredient and paper/ polyethylene: Two (or three) layers of paper/polyethylene  and then the active ingredient “sandwiched” in the middle using heat sealing to create little cells (or sachets). The first improvement was the use of paper coated with polyethylene, which gave more stability and longer duration to SO2 pads.

Then Grapetek developed Uvasys with the idea of “encapsulating” the active ingredient with a material (wax) that would also serve to laminate (stick) the layers together. And instead of using paper coated with polyethylene they used polyester. In other words they added two strong factors in limiting the emissions of SO2 from the pad and reducing concentration inside the box. That created stability and longer life to the pad.

When we came into the market, with already a lot of experience in SO2 pads, we knew that something was not right. There were traditional pads that generated too much SO2 and did not last long enough and in the other extreme Uvasys pads that generated too little and lasted too long.

We found the solution: PROTEKU Laminated and Polypropylene Pads. We wanted a pad that had all the advantages of Uvasys but not the disadvantages. We wanted a pad with the following characteristic:

-          Is easy to use in order to lower labor costs;

-          Eliminates the use of moisture absorbent materials;

-          Efficient in distributing emissions around the box;

-          Capable to limit completely the possibility of active ingredient spills;

-          Capable to limit substantially the exposure of SO2 to the packing workers;

-          Sufficiently long- lasting to yield commercially viable table grapes;

-          Prevents bleaching and maintain stems green and fresh; and

-          It is Superior at controlling Botrytis cinerea.

How do we accomplish all of these? 

We have mastered the appropriate combination of MATERIALS AND PROCESSES. We looked into the elements that give life to the SO2 generating pad: the materials that make up the layers, the excipients, the active ingredient, and the manufacturing process. We change all of them, except of course the active ingredient. We use a balanced mix of paer, polyethylene, polypropylene and other materials. We do not encapsulate the active ingredient. We don´t use extraneous materiasl such of paraffin wax.


And thus conclude the story of three pads:

-          An early version of SO2 pads made or paper led the way in resolving the problems associated with the development Botrytis cinerea during transportation and storage of table grapes.

-          The invention of the laminated Uvasys pad brought about the solution to many of the functional and operational problems of the traditional paper pad.

The introduction of PROTEKU pads, especially the Laminated one, gives birth to a new generation of pads which strikes the right balance in controlling Botrytis cinerea without damaging the grapes while at the same time serving the operational needs of the table grape industry.