01/06/04
Brix versus Yield relationship
A cursory look at the Brix, or sugar content, of a processor tomato would tell you that
the higher the Brix, the better it is, if you are going to turn that tomato paste or dice, which is
what happens to the vast majority of California's processed tomato crop. After all, if the Brix
is higher, the tomato has less water and more solids. The percentage of solids directly relates
to the percentage of that tomato that can be processed into paste or dice. Higher Brix results
in a higher utilization of the tomato or more pounds of paste per ton, as the table in this story
shows. If a processor gets a higher yield of finished product per ton, he and the industry stand
to gain economically in a number of ways. First off, transportation costs from the field to the
processor per ton of finished product will be less. This would also be beneficial to the overall
economy as it results in better utilization of our resources. Same utilization of resources
argument can be made at the processing facility as less energy will be used to make a pound
of finished product if the percentage of solids is higher.
So it seems pretty simple. Growers should be doing whatever they can to increase Brix.
But it isn't that easy. Tradition, good growing practices and the economic structure of the
industry combine to create the current scenario, which may not be the most optimal, but it
works.
Brix vs. Yield
The Brix vs. Yield relationship is an interesting one. Though this is probably fairly
elementary for most growers, it makes sense to begin this discussion with that relationship.
Tim Hartz, a University of California at Davis researcher, has been working on a project to
increase Brix for a number of years. His progress has been reported on in this magazine over
the last couple of years, with the most recent article in the last issue of the California Tomato
Grower (Feb/March 2004, page 17). In addition, researcher Hartz has personally reviewed
countless other studies and projects that were designed to increase Brix.
So it is with a great deal of confidence, that, everything else is being equal, he can say the
only way to absolutely increase Brix level of a specific tomato variety is through
manipulating the amount of water that plant and tomato receive. Simply stated, a grower can
stress the field reducing the amount of water weight in a tomato, increasing the Brix or
soluble solids.
Hartz said there is a linear relationship between Brix and yield, so as a grower stresses the
field and increases the Brix of a particular field of tomatoes, he will decrease the yield. On a
best case scenario, a grower's Brix yield will remain unchanged. For example if he has a Brix
of 5.0 for an acre of tomatoes that yield 40 tons, his Brix yield would be 2.0 tons for that acre
(40 tons x .05 soluble solids). If through manipulating the water for that field, the grower was
able to increase his Brix to 5.2, the best he could hope for, assuming all other factors
remained unchanged, would be the same Brix yield with tonnage dropping to less than 38.5
tons.
This is true because the Brix gain is coming about purely because of the decrease in water in
the tomato itself. This decrease in water will result in a decrease in total yield for the field.
Of course, growers on different ground using different varieties and having different pest
situations and different fertilizer programs will have varying Brix/Yield relationship. And
some growers may not be optimizing that relationship. But for any specific grower to
increase his own Brix on his own field for a specific variety required a drop in yield.
(Researcher Gene Miyao has begun a project to analyze fields that have both high Brix and
high yields to see what factors might be at play.)
But for the time being, Hartz work has shown only an inverse relationship between yield and
Brix. How a grower manages this relationship is critical. This has become increasingly
important as the use of drip irrigation has increased yields by increasing the water weight of
the fruit. Just as the linear relationship works as Brix is increased, it also works in the
opposite direction as yields are increased. Hartz' work has shown that the increased yields
from drip irrigation have come at the expense of Brix.
This is not a value proposition that the processors have embraced. As yields go up, and Brix
decline, the processor has to spend more money for the raw product per pound of paste, and
also has to pay more in production and transportation costs.
As a rule of thumb, Hartz and his colleagues have shown that an increase in Brix results in a
per acre decrease in yield. He said the timing of the decrease in irrigation to stress the field
and increase the Brix is critical. A grower that does not manipulate this irrigation deficit
properly risks decreasing yield more than he increases Brix, and lowering the Brix yield of the
acre. In that scenario, he might produce a high Brix yield per ton harvested, but economically
he will suffer and he might not deliver the tonnage contracted for. Managing the deficit is
tricky, but Hartz said it is very doable. In fact he believes virtually every variety will react to
the water deficit reduction program he has developed, and produce a tomato with a higher
soluble solids.
Processor View
From the processor's point of view, a high Brix yield is purely an economic issue. As the
table below shows, a processor saves money if he processes a tomato with higher soluble
solids because he will produce more paste per ton from that tomato than the same variety with
lower Brix.
Rich Rostomily of The Morning Star Packing Company produced the information on the next
page to further this discussion. As the figures show, there is easily-measured economic
advantage to producing a tomato with a higher Brix. In the example given, Rostomily showed
that a tomato with a Brix of 5.1 vs. 5.0 was worth about $1.55 ton to the processor.
Conversely, 4.9 Brix is worth less.
Of course, having a tomato with a high Brix is not always the goal. Stuart Woolf of Los
Gatos Tomato Products said processors have many different customers with different wants
and needs that require different tomatoes. While economically a high Brix tomato might be
the least expensive to process, some customers are looking for other characteristics such as
high viscosity. While high viscosity doesn't necessarily mean low Brix, it means using a
particular variety for its viscosity, not for its Brix.
Woolf said his firm doesn't pick varieties based solely on high Brix, nor does he want growers
to pick varieties based solely on tonnage. "The best scenario for us is for a grower to surpass
the average Brix regardless of what variety he grows."
He said it is a simple matter of "doing the math." As the above figures show, the higher Brix
content of a tomato, the less it costs to process the tomato in relationship to the yield of
finished product.
The Grower Perspective
As one might imagine, growers were a bit reluctant to talk on the record regarding the
Brix/Yield debate. Off the record, some were willing to share their thoughts.
Longtime U.C. Farm Advisor Gene Miyao summed up the grower's perspective in an email
response: "I think given the choice, most growers would select a variety to consistently yield
well. With it would be packaged lots of disease resistance, good horticultural characteristics
(manageable vine, good canopy cover over the fruit for sun burn protection, vigorous, matures
uniformly, easy to harvest, etc.). However, the list of varieties is largely controlled by
processors selecting the varieties and narrowing the options for their contracted growers.
Processors are making the variety decisions more than the individual grower."
He continued: "The desirable fruit quality characteristics are processor driven (but clearly also
good for the grower in the long run - meeting the consumer preferences). With so many
different processed products (paste-oriented, soups, ketchup, diced/whole peel, sauces, etc.)
having a general performer is becoming more difficult. Each of these end products have
specific raw product requirements. Paste is a Brix/soluble solids driven product. The
industry is heavily weighted in producing paste rather than the other end products. And
within harvest day, for the processor, they are juggling loads coming in with volume they can
process of any particular finished product (assuming they produce more than just bulk paste).
What doesn't make whole peel, may end up in the paste line. So something that is great for
whole peel, may also be better if it also had some decent Brix levels (since a good variety may
only produce 50 percent acceptable whole peel tomatoes in a truck load delivery). Of the
general fruit quality characteristics, it appears that firm fruit with high solids and good color
are important. The issue of viscosity and consistency of product is also an important
component."
Speaking specifically of Brix, he reasoned that it is a topic of discussion because it can be
specifically measured...a fact most other characteristics don't share with it. "I suspect the
reason Brix is talked about so much is because it comprises the biggest volume of the end
product. It also is easily measured and quickly measurable."
A grower, speaking on terms of anonymity, admitted that Brix plays only a limited role in his
varietal selection or cultural decisions. "I can grow for high Brix and I'll be happy to do that
if the processor will pay for it, but they don't."
He said the occasional premium or "deduct" isn't a big enough incentive to drive his decisionmaking process. "I have very little choice in picking a variety," he said. "I usually only have
four or five varieties to choose from and I pick for yields."
Economic Drives Decisions
While Brix deductions or premiums are part of most processing tomato contracts, it is clearly
yields that drive the contract and the growers' decisions.
Hartz said in a perfect economic model with no other factors, Brix yield might be the best
way to price tomato processing contracts but "we don't live in a perfect world. There are
many other factors."
Woolf agreed stating that Brix is not always the most desirable criteria so it doesn't make
sense to use that as the basis for pricing. "I agree with having a baseline price (based on
tonnage)."
Hartz again does not see anything wrong with the way the industry has operated for the better
part of 50 years. But he said if processors owned all of their own fields, it would change the
dynamic and Brix yield would probably gain in importance.
For the time being however, growers are going to continue to try to push the tonnage yield
envelope while keeping the Brix numbers in line with processor wishes.
The Value of Brix
Question: If the factory wishes to produce 1,000,000 pounds of paste, what volume of tomatoes are required
if the incoming soluble solids are 5.0% and 5.1%?
Paste requirement - pounds
Paste NTSS
Factory Yield
Tomatoes required - tons
Pounds of tomatoes per lb of paste
Delivered tomato cost @ $60/ton
Delivered tomato cost per lb of
paste
Value of tomatoes w/ higher solids
5%
1,000,000
31%
97%
3195.9
6.39
$191,752.58
Tomato Soluble Solids
5.1%
1,000,000
31%
97%
3133.2
6.27
$187,992.72
00.1918
00.1880
0
$1.20
Question: If the factory capacity is 400 tons per hour, how many hours would they need to run given the
same conditions above?
Factory capacity - tons/hr
Hours needed to run paste requirement
Factory variable cost - $ per hour
Factory variable cost - total $
Factory variable cost per lb of paste
Value of tomatoes w/ higher solids
400
8
2000
15979.38
0.0160
0
400
7.8
2000
15666.06
0.0157
0.10
Question: If the factory has contracted the required tomatoes above expecting 5.0% soluble solids but
receives 5.1% soluble solids, how much more paste could the factory produce?
Tomatoes delivered - tons
Paste produced - lbs
Average $ contribution* per lb of paste
Average $ contribution* - total $
Value of tomatoes w/ higher solids
3195.9
1,000,000
0.04
40000
0
3195.9
1,020,000
0.04
40800
0.25
Total value of tomatoes w/ higher solids
0
1.55
(* = Fixed costs contribution)
Source: The California Tomato Grower