Statistical Model Reduces Chicken Giveaway

 One would assume that a 4-pound value pack of chicken breast fillets bought in the local supermarket actually weighs 4 pounds. But it may weigh up to 13 percent more than that. This kind of overfill proves costly to poultry processors.

Food marketing changes in the United States have led to a shift from unit pricing to minimum-weight pricing (MWP) in some wholesale and retail situations. Under unit-pricing procedures, products are priced at a fixed price per unit, for example, 20 cents per ounce. Under MWP, products that meet weight minimums may be of varying sizes—but are priced at fixed rates. In MWP, it is sometimes necessary to fill containers beyond the stated weights in order to meet the weight minimum. Product above the stated weight is commonly designated as giveaway.

ARS food scientist Louis L. Young developed a statistical modeling approach to minimize the amount of overfill in prepackaged poultry products.

"During a visit to a poultry processing plant, I saw enormous variations," says Young. "Processors overfill bags to meet minimum weights. If a bag is short by 1 ounce, a whole breast fillet is needed to bring the bag into compliance."

Young simulated a scenario of packing 4-pound packages of chicken breast fillets. The bags contained from six to nine breast fillets. These pieces were presorted into six weight categories, or quantiles. The mean weights of the quantiles were 168, 209, 231, 248, 262, and 277 grams.

When the bags were assembled using breast fillets chosen from only two of the weight categories, greater variation occurred in the bag weights—up to 25 percent overfill was noted. For a 4-pound bag of chicken breast fillets, this means an extra pound given away by the wholesaler.

But when breast fillets were chosen from selected combinations of the six categories, there was much less variation from the 4-pound goal than when the fillets were randomly chosen. The amount of giveaway decreased to about 2.5 percent.

"The trick is to choose combinations of categories that minimize variation in overall package weights," contends Young.

The statistical model indicates that presizing the product and then packaging by specific numbers of pieces from each weight category may help reduce the amount of giveaway, a cost savings for wholesalers--especially of high-value products such as chicken breast fillets.

"This allows us to alter the process without having to alter technology," says Young.—By Sharon Durham, Agricultural Research Service Information Staff.

Louis L. Young is in the Poultry Processing and Meat Quality Research Unit, Richard B. Russell Research Center, 950 College Station Rd., Athens, GA; phone (706) 546-3416, fax 706-546-3633. 

"Statistical Model Reduces Chicken Giveaway" was published in the July 2001 issue of Agricultural Research magazine.