Hot-fill pasteurization of cucumber pickle spears: An alternative to tunnel pasteurization

Authors: YAVUZ, NIHAT - North Carolina State University; FOSTER, L. ANDERSON - North Carolina State University; SHARMA, TANYA - North Carolina State University; PATEL, KRISHA - North Carolina State University; STOFOROS, GEORGE - North Carolina State University; SANDEEP, KANDIYAN - North Carolina State University; PLANITKAR, PAUL - North Carolina State University; Breidt, Frederick

Submitted to: Food Protection Trends
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2018
Publication Date: 7/1/2019
Citation: Yavuz, N., Foster, L., Sharma, T., Patel, K., Stoforos, G., Sandeep, K.P., Planitkar, P., Breidt, F. 2019. Hot-fill pasteurization of cucumber pickle spears: An alternative to tunnel pasteurization. Food Protection Trends. 38(4):258-265. http://staging.nxtbook.com/nxtbooks/trilix/fpt_20180708/stage.php.

Interpretive Summary: Large scale thermal processing of acidified vegetables, including commercial processing of cucumber spears in jars, is typically done with a hot water or steam tunnel pasteurizer. Jars packed with cucumber spears in a flavored brine are capped and travel on a belt for heating and cooling in the tunnel apparatus. To reduce energy costs and water usage, we have developed a hot-fill method for jars of cucumber spears that can achieve thermal treatments similar to tunnel Pasteurizer processes. This method involves refilling jars multiple times (3 times) with a hot brine prior to capping, thereby eliminating the need for the hot water or tunnel pasteurizer. Because the first two filling cycles can use hot water or lightly salted water that can be recycled, heat in the brine is retained and water usage is limited. For a commercial process the final hot fill of the jars prior to capping could be done with the typical flavored cover brine for the product. We found that this method can achieve similar heating characteristics as compared to tunnel pasteurizer processes, including meeting food safety requirements for killing bacterial pathogens, as well as achieving heating times for quality factors, such as killing spoilage organisms and inactivating softening enzymes. While further development is needed to automate jar inversion and refilling, we have established that this method may be useful for cucumber spear products, and it has the potential to save energy and water used compared to current practices.

Technical Abstract: For commercial production of acidified vegetable products, a tunnel pasteurizer is typically used for thermal processes. To help reduce energy costs and use of water, we developed a hot-fill method for pasteurization of cucumber pickle spears in 0.7 liter (24 oz) jars. The method required refilling jars three times with 70°C to 85°C brine. Initial cucumber spear temperatures up to 60°C were tested with insulated or uninsulated pickle jars. The data showed that for cucumber spears with an initial targeted temperature of 40°C or 60°C, a hot fill method could achieve or exceed a temperature of 73.9°C (165°F) for up to 13.9 min. These conditions exceed published 5-log reduction values (F160 of 5.6 min) for food pathogens and were sufficient to meet typical industry processing conditions of 10 or more min at 73.9°C, to destroy spoilage bacteria and inhibit cucumber softening enzymes. A simulation model was developed that may be useful for the optimization of brine temperatures and processing times. Although further development of processing equipment may be needed for inverting and refilling jars, the in-jar pasteurization process has potential application for cucumber spears and related products.