Dr Desmond Layne, associate professor of pomology, tree fruit specialist, and state program team leader for horticulture at Clemson University

Stone Fruit

Truth In Advertising

Desmond R. Layne
dlayne@clemson.edu

The Federal Trade Commission (www.ftc.gov) guides all businesses on the topic of “truth in advertising.”  According to the Act, advertising must be “truthful and non-deceptive, advertisers must have evidence to back up their claims, and advertisements cannot be unfair.”  In the produce business it’s difficult to strictly enforce these rules, because quality is such a subjective characteristic.  How often do we see the words, “fresh, tree-ripe, sweet, juicy, tasty, etc.” on a sign or a box of fruit?  Maybe these characteristics are hard to measure, but there is an implied experience for the consumer based on the quality of the product at the time of consumption.  This experience may be delightful or disappointing.  It is delightful when the fruit is picked at the right time and handled properly, but it may be disappointing when it is picked immature or held too long at the wrong temperature.

Listen To The Consumer
The consumer has the final say about your fruit quality, and the national trend for per capita peach consumption is downward, indicating that consumers are not happy.  When surveyed, many people indicate that they were disappointed in the quality and taste of the fruit.  If consumers had a bad experience with their first peach of the season from the local chain store, they may move on from peaches to purchase other fruits for the rest of the summer.

By contrast, local markets often do a brisk business with repeat customers all summer long.  This is partly because many of these markets allow consumers to taste the fruit before buying it.  In this way, the consumer will do his/her own quality assessment before purchasing to ensure satisfaction.  The grower/farmer may get direct feedback if the fruit was immature and dissatisfying!

Fruit size, color, aroma, texture, and taste all are affected by the fruit’s stage of development at harvest.  Various criteria are used commercially to determine when to pick a particular cultivar.  Some standards that are used include the historical calendar picking date and a minimal marketable size (or larger) for that time during the season, etc.  For traditional, yellow-fleshed peach cultivars that have a partial red blush at maturity, change in background color (green to yellow/orange) and fruit size are well-established harvest criteria.  For newer cultivars that become solid-red before they are mature, background color estimation is much more difficult.  Fruit diameter is also an imperfect measure of maturity and it can change considerably in the last two weeks while fruit hang on the tree depending on cropload, rainfall, etc.

Whether fruit is destined for the distant or local market, it is vital that the grower, field supervisor, and picking crew are all on the same page to ensure that fruit of a given cultivar are picked at the optimal stage of maturity.  A well-trained field manager who closely supervises the picking crew and checks its work regularly is necessary.  This is particularly important when harvesters are paid by piecework as opposed to by the hour.

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Photo 1. Puncture pressure (flesh firmness) determination using a penetrometer (measured value on yellow scale is 8 pounds).

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There are some objective methods for estimating proper harvest maturity.  Flesh firmness can be evaluated by measuring the puncture pressure with a penetrometer (see Photo 1 on the right).  This tool measures the pounds of force required to push an 8-millimeter tip into the flesh of the peach.  A lot of information is available about the firmness of different cultivars at ideal harvest maturity.

Another useful measurement is the sugar content (°Brix), or soluble solids concentration, which can be checked with a refractometer (see Photo 2 on the right).  It does take a little bit of know-how and experience to make consistently accurate measurements, but it is not rocket science.  The procedures can be taught to a high school student or other laborers.  Because these tools require a “destructive” harvest, they do result in loss of a small subsample of fruit, but this is a negligible cost concerning the value of an entire crop.
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Photo 2. Soluble solids concentration determination using a refractometer (measured value on scale is 17 °Brix).

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Maturity Determination

Ideal maturity determination in the commercial peach industry today is tricky because there is considerable variation among cultivars.  This variation includes skin color (solid red, partial blush, yellow or white), flesh texture (melting, non-melting, stony hard/crunchy), flesh color (yellow, white, or red), and acidity (normal versus sub-acid).  A “one size fits all” approach for maturity determination has obvious limitations.  It may take several tests (size, background color, puncture pressure, brix) to ensure accuracy for each cultivar.  Keeping good harvest maturity records from year-to-year is a good idea!

Research by breeders and postharvest physiologists using trained taste panels indicates that a minimum °Brix level should be in the 10-12 range for consumer eating acceptability.  Puncture pressure for fruit at the local market should be 2 to 4 pounds while fruit being shipped to distant markets can be considerably firmer (i.e. 10 pounds).

One website where refractometers and penetrometers can be found is:  www.qasupplies.com.  In our program, we use the FT-327 model penetrometer with the stone fruit tip (8 millimeter diameter).  Note that this product comes with two different sized tips.  The “stone fruit tip” is the smaller one.  We also use a temperature compensating ATC refractometer.  Together, you can purchase both a penetrometer and a refractometer for less than $400.

So how does your advertising (direct or implied) reflect the consumer experience as they eat peaches grown on your farm?  If they are delighted, as they used to say in the 1980s, “keep on keepin’ on.”  You must be doing things right!  If they are disappointed, perhaps taking a more proactive approach to maturity evaluation might be worth investigating.  Also, if you are growing new solid-red cultivars, sub-acid types, etc., the parameters you are using may need some fine-tuning.

 

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This column by Dr. Desmond R. Layne, “Truth In Advertising” appeared in the March 2010 issue of The American Fruit Grower magazine on pages 42-44.

Desmond R. Layne, Ph.D., is an associate professor of pomology, tree fruit specialist, and state program team leader for horticulture at Clemson University. He is also president of the American Pomological Society.

For more information, go to www.clemson.edu/peach.