Title: Physiological, volatile, and SEM surface effects resulting from cutting and dipping treatments in cantaloupe Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 12, 2011
Publication Date: November 14, 2011
Citation: Beaulieu, J.C., Ingber, B.F., Lea, J.M. 2011. Physiological, volatile, and SEM surface effects resulting from cutting and dipping treatments in cantaloupe. Journal of Food Science. 76(7):S415-S422. Interpretive Summary: Recent human pathogen outbreaks in fresh and fresh-cut produce have refocused much research attention on food safety and efficacious sanitation treatments. Recently, several treatments have been evaluated as a means by which to deliver fresh-cut cantaloupe cubes with acceptable quality, and reduced microbial loads to improve food safety. Much of the research focus has been, understandably, on establishing sanitation treatments, effective levels, and microbial analysis. Volatile and sensory appraisals in most studies are lacking. It has been reported that cut fruit products, prepared for sanitation treatments, or to assess stress response, rapidly loose their typical flavor even when stored under refrigerated conditions. Subsequently, a quality and volatile assessment of various cutting and dipping/bathing treatments was performed in fresh-cut cantaloupe. Thin-sliced cantaloupe tissue had marked color loss, tissue translucency, weight loss, and substantially higher surface area to unit volume, compared with fresh-cut cubes. Washing tissue provided a boundary layer that effectively reduced short-term ester losses in tissue slices and cubes; however, washing both tissue types resulted in approximately 15% reduction in soluble solids. Ester volatile compounds that are known to be important for typical flavor perception decreased 92.9 and 95.8%, respectively, after 1 and 3 days storage in only thin-sliced tissue. Abusive cutting and handling sanitation treatment regimes and storage can radically alter the desirable volatile profile in cut cantaloupe. There is a likely trade off between possible benefits attained by washing and rinsing treatments geared toward microbial reduction, or tissue firmness that provides a protective boundary layer effect and traps flavor volatiles, versus the soluble solid losses that occur during rinsing. We have demonstrated that cutting method and sampling protocol are critically important when using volatiles as a means by which to assess or interpret stress response and ascribe fresh-cut quality. Reduction of tissue size to maximize food-safety sanitation efficacy (e.g. thin slices) will need substantial work to engineer equipment and design protocols to ensure product quality and volatile profiles are not compromised.
Technical Abstract: Previous research examined sanitation treatments on cut cantaloupe tissue, to deliver germicidal and food safety effects; however, an apparent compromise between volatile loss and treatment/sampling efficacy appeared. Subsequently, a physiological and volatile reassessment of thinly sliced tissue versus cubes was performed in cantaloupe tissue. Thin sliced cantaloupe L decreased 27.5, 40.5, and 52.9% in 3, 2, and 1 mm thickness, respectively, compared with cut cubes after 3 days. Overall color (C) decreased in freshly prepared cubes (2.4%) and slices (14.4%) that were washed in cold water. Surface area per unit volume (SA:vol) in slices was 4.1 times greater than typical cubes, as reflected by substantial water loss (20.4%, 9.5%, and 6.7% in 1, 2 and 3-mm slices, respectively) after 1 day at 5 °C. Rinsing cubes and thin-slices with 5 °C deionized water resulted in roughly 15% soluble solids loss. SEM indicated 65.4% reduced cell size in 1-day old thin slices, evidenced by excessive cell damage and desiccation, compared with stored fresh-cut cubes. In thin-sliced tissue exposed 15 min to an open atmosphere (mimic sanitation treatments), total esters decreased 92.8 and 95.8%, respectively, after 1 and 3 days storage at 5 °C. Washing tissue provided a boundary layer that reduced short-term ester losses in slices and cubes. Excessive cutting and sanitation treatment regimes and storage can radically alter the desirable volatile profile of cut cantaloupe. Reduction of tissue size to maximize food-safety sanitation efficacy or delivering items to a niche market will need substantial work to engineer equipment, and develop protocols to ensure that product quality and volatiles are not compromised.