Pretreatments and Miscellaneous Strategies

Treatment of produce with methyl jasmonate prior to MAP has been found to be successful in suppressing fungal decay in a number of commodities, including fresh-cut celery and peppers, grapefruit, papaya, strawberries, zucchini squash, mango, and avocado [35]; the effects and mode of action of jasmonates in reducing disease development differ among various crops and pathogens. Synergistic activity between methyl jasmonate treatments and MAP

has been found for several commodities, including papaya. Gonzalez-Aguilar and others [35] found that exposure of papaya to methyl jasmonate vapor (10~5 or 10_4M) for 16 hours at 20°C inhibited growth of Collectotrichum gloeosporioides and fruit decay in papaya, an effect that enhanced a MAP treatment of 14 to 32 days at 10°C followed by 4 days at 20°C in a modified atmosphere of 3 to 5 kPa O2 and 6 to 9 kPa CO2.

As a treatment prior to MAP packaging, nonionizing, artificial UVC radiation has the potential to be effective in reducing the initial microbial load on produce, providing shelf life extension. UVC has been shown to damage microbial DNA, an effect that weakens or kills microbial cells. Some bacteria have been found to utilize repair mechanisms to overcome DNA damage, and some cells may mutate. Thus typically UVC treatment results in a reduction of microbial load but not complete sterilization. Allende and Artes [13] found that treatments of 254 nm UVC doses up to 8.14 kJ/m2 on Red Oak Leaf lettuce, subsequently stored at 5°C for 9 to 10 days, significantly decreased the growth of psychrotrophic bacteria, yeast, and coliforms. UVC has been shown to reduce postharvest diseases and decay in a variety of whole produce including strawberries, apples, carrots, sweet potatoes, zucchini squash, tomatoes, and onions [13,36]. These different produce typically are smooth surfaced and simple in shape; UVC would not be fully effective on produce with naturally convoluted, rough, or inaccessible surfaces, as radiation would not penetrate into shadowed regions of these types of surfaces.

Some antimicrobial compounds have been found naturally in fruits and vegetables and can be used as additional hurdles in MAP systems. Raw carrots produce compounds antimicrobial towards L. monocytogenes, an antimicrobial effect that is more pronounced in shredded than in whole carrots, and is absent in cooked carrots. Mixing shredded raw carrots with other MP vegetables that did not produce the antilisterial compounds resulted in overall reductions in populations of L. monocytogenes during storage, and a coleslaw mix of shredded carrot and cabbage stored under MAP conditions had less spoilage than either product stored individually [37]. Red chicory has been found to inhibit growth of Pseudomonas spp. and Aeromonas hydrophylla [38], and capsaicinoids found in green bell pepper were hypothesized to be antimicrobial towards Shigella spp. [39]. More knowledge is needed about antimicrobial compounds naturally found in fresh fruits and vegetables in order to utilize their benefits.

Was this article helpful?

0 0
Berry Boosters

Berry Boosters

Acai, Maqui And Many Other Popular Berries That Will Change Your Life And Health. Berries have been demonstrated to be some of the healthiest foods on the planet. Each month or so it seems fresh research is being brought out and new berries are being exposed and analyzed for their health giving attributes.

Get My Free Ebook

Post a comment