Microbial Hygiene Considerations with Mechanical Harvesting of Blueberries

Transcription

1 Microbial Hygiene Considerations with Mechanical Harvesting of lueberries Renée Allen UGA Extension, Alma, GA Dr. Harald Scherm UGA Plant Pathology, Athens, GA Dr. Jinru Chen UGA Food Science, Griffin, GA Dr. Changying Li, UGA

2 Georgia lueberry Industry Located throughout state, but highly concentrated in south Georgia Fresh and frozen markets NASS 2014: 92 M lbs, $109.8 M 52 M lbs fresh, 40 M lbs processed Rabbiteye and Southern Highbush varieties Estimated production value >$335 million (2014 Georgia Farm Gate Value Report)

3 Food Safety and Implications Marketers and clients require product from farms and packing plants inspected by third-party audits Audits require intense cleaning and sanitization protocols Microbial hygiene focused on packing plants mainly Not much focus on farms in reality Current practice may or may not include rinsing of harvesters Food Safety & Modernization Act requires better cleaning and sanitization in fresh product industry Exports tested for micros upon delivery

4 Known Human Disease Outbreaks in lueberry Industry Form Country of origin Pathogen Year Outbreak location No. of cases (deaths) Comments Fresh New Zealand Hepatitis A 2002 New Zealand 43 (1) Mode of contamination was likely infected food handlers or contaminated ground water (pit latrines located near orchard, with no hand-washing facilities) NR* NR* Salmonella Muenchen 2009 United States, multiple states 14 (0) Consumed in private home(s) Fresh United States (Georgia) Salmonella Newport 2010 United States, Minnesota 6 (0) Traced to single grower *Not reported Palumbo et al Limited number of cases No Listeria spp. outbreaks Let s take due diligence now

5 Cleaning and Sanitization of Farm Equipment Recommended for decades Only recently does one see practical application Farmers find sanitation protocols timeconsuming and laborintensive Hwang et al. 2014

6 What is the microbial load and level of indicator organisms on various mechanical harvester surfaces?

7 Harvester Microbial Safety 2015 & 2016: Objectives Determine microbial loads on different harvester surfaces during different times of day What are the most problematic surfaces? Determine microbial loads on fruit before and after they pass through harvester Does harvester increase microbial risk? Focus on environmental indicator organisms: Determine general microbial load; could impact post-harvest decay/fruit quality Total aerobic bacteria (TSA) Total yeasts and molds (apda) High numbers increase risk of mycotoxin production in product Indicators of fecal contamination Enterococci (Enterococcus agar) Coliforms and fecal coliforms (Maconkey agar) Fecal coliforms of greatest concern because indicator of E. coli and other pathogens present

8 Harvester Surfaces Acetyl delrin eater bars Conveyor belts Gescosteel.com High density polyethylene Lug Havenharvesters.com Highcor.com Dbe.ca Plexiglass Catcher pan fish scale Stainless steel Sides of harvester Metal conveyor belts Rubberized plastic canvas Filling flap

9 Sample Surfaces #1: upper rod #2: lower rod

10 Sample Surfaces #3: upper wall #4: lower wall

11 Sample Surfaces #5: fish scales

12 Sample Surfaces #6: conveyor belt

13 Sample Surfaces #7: lug

14 Additional Sample Surfaces for Top-loading Harvesters #8: vertical conveyor #9: filling flap

15 Surface Swabbing and Sample Processing Total of 7 harvesters sampled three times a day (2015 & 2016) Swabbed 100 cm 2 surface area with sterile sponge saturated with D/E neutralizing buffer Collected sponge in sterile sampling bags Dilution-plated in duplicate on appropriate media 50 g of pre- and post-fruit washed in PS for 30 min and dilution-plated

16 2016 Total Aerobic acteria 2016 Total aerobic bacteria Upper rod Lower rod D CD AM Noon PM Upper wall D Lower wall C Catch plate A Conveyor A Lug CD 1e+1 1e+2 1e+3 1e+4 1e+5 1e+6 1e+7 1e+8 1e+9 1e+10 CFU/cm 2

17 2016 Total Yeast & Mold 2016 Total yeast and mold Upper rod Lower rod AM Noon PM Upper wall Lower wall Catch plate A Conveyor A Lug 1e+0 1e+1 1e+2 1e+3 1e+4 1e+5 1e+6 1e+7 CFU/cm 2

18 2016 Coliforms 2016 Coliforms Upper rod Lower rod AM Noon PM Upper wall Lower wall Catch plate Conveyor A A Lug CFU/cm 2

19 2016 Fecal Coliforms 2016 Fecal coliforms Upper rod Lower rod AM Noon PM Upper wall Lower wall Catch plate Conveyor A A Lug A CFU/cm 2

20 2016 Enterococci 2016 Enterococci Upper rod Lower rod Upper wall C C C AM Noon PM Lower wall C Catch plate Conveyor A Lug C CFU/cm 2

21 Harvester Surfaces Significant, Time Generally Not Table 1. P-values of mixed-model analysis of variance for the effects of harvester surface (seven different surfaces) and time (AM, noon, PM) on the population density (log 10 colonyforming units per cm 2 ) of microbial indicator organisms across seven mechanical blueberry harvesters, 2015 and Aerobic bacteria Yeasts & molds Coliforms Fecal coliforms Enterococci Harvester surface < Time Surface x time Harvester surface < < < Time Surface x time

22 2016 Fruit: Total Aerobic acteria 1e Total aerobic bacteria 1e+5 AM Noon PM CFU/g 1e+4 1e+3 1e+2 1e+1 Pre-fruit Post-fruit

23 2016 Fruit: Total Yeast & Mold 1e Total yeast and mold 1e+4 AM Noon PM CFU/g 1e+3 1e+2 1e+1 Pre-fruit Post-fruit

24 2016 Fruit: Coliforms 2016 Coliforms AM Noon PM CFU/g Pre-fruit Post-fruit

25 Difference between Pre & Post Fruit Not Significant Table 2. P-values of mixed-model analysis of variance for the effects of fruit location (before entering or after leaving the harvester) and time (AM, noon, PM) on the population density (log 10 colony-forming units per g) of microbial indicator organisms across seven mechanical blueberry harvesters, 2015 and Aerobic bacteria Yeasts & molds Coliforms Fecal coliforms Enterococci Fruit location Time Location x time Fruit location Time Location x time

26 Conclusions 2016: Harvester surfaces significant for all groups, total aerobic bacteria, yeast & mold, coliforms, fecal coliforms, and enterococci 2015: surfaces significant for 3 out of 5 organism groups Populations consistently highest on horizontal conveyor belt, catcher plate, followed by either the lower wall or lug Time only significant in 2 out of 5 cases each year In general, time not significant Only case in both years significant was for fecal coliforms at AM

27 Conclusions In none of the cases was microbial load increased significantly for fruit after they left the harvester, compared with when they entered it

28 Harvester Microbial Safety Studies Tentative Conclusions Harvester surfaces carry high microbial loads Conveyors, catcher plates, lower walls, and even lugs tend to have highest microbial loads For total aerobic bacteria, yeast & mold, coliforms Opportunity to target these areas during cleaning and sanitization of mechanical harvesters Growers should be cognizant of how lugs are handled, stored overnight, etc. Enterococci and fecal coliforms only sporadically detected Room for improvement in C & S of harvesters; let s take due diligence to prevent a foodborne illness outbreak However, important to note that fortunately, harvesters are not showing direct impact on microbial load of fruit

29 Future Plans Identify representative aerobic bacteria, yeast, and mold isolates cultured from harvester surfaces for use in biofilm studies Test biofilm development with these isolates in different combinations with a plant pathogen (i.e. Exobasidium maculosum) Test cleaning and sanitizer efficacy on these harvester surfaces, including novel padding and netting type surfaces Develop rapid method cleaning check for growers