Evaluation of combination treatment processes for the microbial decontamination of pork trim.

Combination treatment processes for the microbial decontamination of pork trim were developed and evaluated. Lean pork trim tissue (LPT) and fat-covered pork trim tissue (FPT) inoculated with swine feces were treated with intervention processes as follows: (i) control (untreated), (ii) water (15 degrees C, 120 s), (iii) water followed by lactic acid wash (15 degrees C, 75 s), (iv) combination 1 (water plus hot water [65.5 degrees C, 15 s] plus hot air [510 degrees C, 60 s] plus lactic acid), (v) combination 2 (water plus hot water [82.2 degrees C, 15 s] plus hot air [510 degrees C, 75 s] plus lactic acid), and (vi) combination 3 (water plus hot water [82.2 degrees C, 45 s] plus hot air [510 degrees C, 90 s] plus lactic acid). Populations of aerobic bacteria, psychrotrophic bacteria, coliforms, Escherichia coli, and lactic acid bacteria were determined before and after treatment and at days 2 and 7 of 4 degrees C storage. Regardless of the intervention treatment, lower microbial populations were observed on FPT than on LPT immediately after treatment and during the 7-day storage period. Both LPT and FPT treated with water plus lactic acid, combination 1, combination 2, and combination 3 had lower remaining populations of all microbial groups immediately after treatment than did water-treated samples. Populations of aerobic bacteria, coliforms, E. coli, and lactic acid bacteria on either LPT or FPT did not statistically increase during the 7-day storage period. On LPT, populations of psychrotrophic bacteria grew during 4 degrees C storage but remained lower at day 7 on LPT treated by combinations 2 and 3 (2.29 and 1.89 log10 CFU/cm2, respectively) than on LPT treated with water (4.07 log10 CFU/cm2) or water plus lactic acid (3.52 log10 CFU/cm2). Populations of psychrotrophic bacteria remained below detectable levels throughout the 7-day storage on FPT treated with water plus lactic acid or any of the three combination treatments. Treatment of pork trim with any of the combination treatments significantly (P < 0.05) affected the color and emulsion stability of the ground pork. Water and water plus lactic acid were the most favorable treatments in reducing microbial populations on pork trim without affecting the quality attributes of the ground pork.

Microbial and quality attributes of ground pork prepared from commercial pork trim treated with combination intervention processes.

The effects of combination intervention treatments of commercial pork trim on microbial and quality attributes of the subsequent ground pork were examined. Fresh commercial pork trim was inoculated with swine feces and subjected to five different intervention treatments: (i) control (untreated), (ii) water (15 degrees C, 120 s), (iii) water followed by 2% lactic acid wash (15 degrees C, 75 s), (iv) Combination 1 (water plus lactic acid plus hot air [510 degrees C, 90 s]), and (v) Combination 2 (hot air plus water plus hot air). Following treatment, the pork trim was stored at 4 degrees C for 24 h, then ground, stuffed, vacuum packaged, and stored at 4 degrees C for 21 days. Populations of aerobic bacteria, coliforms, Escherichia coli, and lactic acid bacteria in the ground pork were monitored before treatment, after treatment (day 0), and at 2, 7, 14 and 21 days. In addition, uninoculated pork trim was treated as described above, and the color and emulsion stability of the ground product was evaluated. Ground pork prepared from trim treated with any of the treatment processes had lower initial microbial populations compared to the untreated samples. The applications of water plus lactic acid or Combination 1, which included a lactic acid wash, were more effective than water or Combination 2 at both reducing initial populations and suppressing the growth of aerobic bacteria, coliforms, and E. coli in ground pork during refrigerated storage. By day 21, populations of aerobic bacteria in ground pork prepared from control, water-treated, and Combination 2-treated trim were 8.22 to 8.32 log CFU/g, but in water plus lactic acid and Combination 1 ground pork, populations were 6.32 and 4.90 log CFU/g, respectively. Among the trim interventions examined, Combination 1 was most detrimental to the color and emulsion stability of the ground pork. The water plus lactic acid treatment provided the greatest microbial reduction and inhibition without large negative effects on quality attributes of the ground pork.

Occurrence of fumonisins in corn-based food products.

Corn-based food products obtained from commercial outlets in three different parts of the U.S., Maryland, Nebraska, and Arizona were analyzed for total fumonisins by a commercial competitive direct enzyme-linked immunosorbent assay (CD-ELISA) and for fumonisin B1 (FB1) by high-performance liquid chromatography (HPLC). The highest fumonisin concentrations were found in samples collected in Maryland, where all 18 samples were found positive for fumonisins (200 to 7,450 ng/g of food) by CD-ELISA and 15 of the 18 samples (83%) were found positive for FB1 (< 75 to 5,916 ng/g) by HPLC. Fumonisins were also detected by CD-ELISA in 14 of 15 samples collected in Arizona with concentrations ranging from 200 to 1,450 ng/g, but analyses by HPLC showed that only 8 of 15 samples (53%) were positive for FB1 (< 75 to 1,565 ng/g of food). Of the 23 samples collected in Nebraska, 20 (87%) were positive for fumonisins (200 to 2,500 ng/g) by CD-ELISA, but only 10 (44%) were positive for FB1 (< 75 to 927 ng/g) by HPLC. The highest fumonisin and FB1 concentrations were found in cornmeal samples, ranging up to 7,450 ng/g of cornmeal by CD-ELISA and 5,916 ng/g by HPLC. These findings indicate that there may be a risk of human exposure to fumonisins through the consumption of some corn-based foods.

Stability of fumonisins in thermally processed corn products.

Little is known about the stability of fumonisins in corn-based foods during heating. This study investigated the effects of canning, baking, and roasting (dry heating) processes on the stability of fumonisins in artificially contaminated and naturally contaminated corn-based foods. All samples were analyzed for fumonisin levels by both a commercial enzyme-linked immunosorbent assay (ELISA) and a high-performance liquid chromatographic (HPLC) method. Canned whole-kernel corn showed a significant (P < or = 0.05) decrease in fumonisins by both ELISA (15%) and HPLC (11%) analyses. Canned cream-style corn and baked corn bread showed significant (P < or = 0.05) decreases in fumonisin levels at an average rate of 9% and 48%, respectively, as analyzed by ELISA. Corn-muffin mix artificially contaminated with 5 micrograms of fumonisin B1 (FB1) per g and naturally contaminated corn-muffin mix showed no significant (P < or = 0.05) losses of fumonisins upon baking. Roasting cornmeal samples artificially contaminated with 5 micrograms of FB1 per g and naturally contaminated cornmeal samples at 218 degrees C for 15 min resulted in almost complete loss of fumonisins.