Sales of produce in clamshells and bags continue to rise at the expense of counterparts sold loose, according to the latest data from Nielsen Perishables Group.

Packaging is gaining even in bulk-traditional items, like avocados, bananas, citrus and grapes, according to the survey, which traced yearlong sales patterns in retail produce departments from July 2010 through July 2011.

It’s the most recent such survey released by the tracking firm formed in January 2012 by a merger of Chicago-based Nielsen and the Perishables Group.

Packaged formats, particularly clamshells, already dominated certain categories, such as berries, where the percentage of product sold in packaged form remained unchanged, at 98.9%. On the vegetable side, packaged carrots accounted for 90.9% of sales, which was virtually unchanged from 2010. Salad mixes already were 100% packaged.

Bulk sales accounted for most sales of apples (72.7%), avocados (93.3%), cherries (94.9%), citrus (87.5%), grapes (94%), pears (98.1%), specialty fruits (94.2%), sweet corn (98.4%), peppers (90.3%) and tomatoes (75.9%), but packaging showed year-over-year gains in each of those categories.

The gains have two messages, said Steve Lutz, Wenatchee, Wash.-based vice president of Nielsen Perishables Group.

“One is the longer-term trend toward packages continues, and you can see that across the board,” he said.

Sales of packaged product are increasing in all major categories of fruits and vegetables, he said.

The numbers also convey meaningful information on the effect packaging has on total category sales, Lutz said.

“In most cases, you’re getting a pretty good dollar generation by these packaged products. It’s disproportionate to the volume represented,” he said.

That quickly leads to a conclusion that retailers can increase packaging because the revenue generated per square foot is higher, Lutz added.

“There’s also a recognition on the part of retailers that they can choose to carry packs that appeal to specific groups,” Lutz said.

Shelf-life issues come into play, as well, said Ron Potterman, director of sustainability with Elmwood Park, N.J.-based Sealed Air Corp.

“I was recently at a Walmart Canada conference in Toronto, and they showed 75% decrease in shrink because of packaging,” he said.

Potterman said attendees at the conference reported bell pepper shrink rates of 14% on loose product.

Consumers likely don’t notice, but packaging is having a positive effect on the food supply, Potterman said.

“To many people, packaging is something we have to dispose of and we don’t think of the value of what it did to keep food safe and wholesome,” he said.