Food Engineering

Grilled chili pepper producer increases yield

January 1, 2010
Mexican food maker quadruples output and slashes energy costs with modified flame griller.

Before and after: (Left) Chili peppers enter Agroin’s old griller, which produced inconsistent results and didn’t have output to match the freezer’s capacity. (Right) New griller from Unitherm has three to four times the output and provides consistent grilling on all sides. Source: Unitherm.


Founded in 2003, Agroin operates as a division of La Huerta, one the largest frozen produce exporters in Mexico and a supplier of frozen vegetables to Wal-Mart. Agroin processes the frozen poblano chili pepper line for La Huerta, but its output was limited by its hand-built griller.

 “We have very limited production at our plant here in Mexico, but our clients were asking for more and more of our chili pepper products,” says Leonardo Randolph, production manager for Agroindustria de Aguascalientes S.A. de C.V.

“We grow and harvest our own peppers, wash them, and then roast them,” explains Randolf. “Afterwards, we peel off the blackened outer skin and then immediately freeze and package the product in different presentations. But our old griller...was a bottleneck in the whole process. We had enough demand to more than triple our output, but we realized that we would need three more of our old roasters to meet the throughput that our new freezer was capable of handling. We needed to process one metric ton per hour, but our existing griller could only roast 250 kg per hour.”

Aside from insufficient capacity, the construction of the old griller produced inconsistencies in roasting, as the distance between the gas burners and the product handling equipment could vary, making it difficult to quickly and thoroughly peel off the unevenly-blackened skin. At the output end of the griller, some of peppers would fail to be separated from the springs that carried them, which required a person to pull out the stuck peppers by hand.

While attending a trade show in Chicago, Randolph and La Huerta’s Ricardo Arteaga Barba were introduced to an equipment manufacturer who offered to work on a solution.

“Because our pepper-roasting process is unique, we were not sure that any standard griller could do the job correctly and preserve the special taste of our product,” recalls Randolf.

“They brought in the same type of green poblano chili peppers we use, roasted them in their griller, and made adjustments until they came out the way we wanted,” says Randolph. “We tasted them and they were really good. We could see that this was going to work for us and provide the production volumes we were seeking.”

A final design was selected for a single-flame griller that could meet Agroin’s goal of one metric ton of product per hour. Preservation, if not improvement, in product quality was achieved by the grilling system’s ability to roast each pepper on all sides, providing the sought-after consistency.

“Unitherm’s griller was so efficient that we only needed one unit to do the job of three or four of our old grillers,” says Randolph. “As such, we expect our energy consumption to shrink tremendously. But the best part is that we expect the quality to improve, because with the new equipment we can control the speed of the griller bed, the amount of burners that can be turned on, and the quantity of heat going out of the griller.”

An unexpected gain from this design is increased yield. “By weight, the product shrinks by about 20-25%, and this is normal during the roasting process,” comments Randolph. “However, the new griller can limit that loss to 15-20%.”

For more information: Adam Cowherd, 918-367-0197, adamc@unithermfoodsystems.com