Evaluating Heat Treatment Evaluating Heat Treatment Effectiveness - PowerPoint PPT Presentation

Evaluating Heat Treatment Evaluating Heat Treatment Effectiveness Effectiveness Bh. . Subramanyam Subramanyam ( (Subi Subi) ) Bh Department of Grain Science and Industry Department of Grain Science and Industry Kansas State University Kansas State University Manhattan, KS 66506 Manhattan, KS 66506 Tel: 785- -532 532- -4092 4092 Tel: 785 Fax: 785- -532 532- -7010 7010 Fax: 785 E- -mail: mail: bhs bhs@wheat. @wheat.ksu ksu. .edu edu E May 15, 2004 Heat Treatment Workshop May 15, 2004 Heat Treatment Workshop

Insect Species Vary in Their Insect Species Vary in Their Susceptibility to Heat Susceptibility to Heat

Fig. 1. •Red flour beetle •Newly hatched larvae are heat tolerant 500 Eggs Young larvae Old larvae 400 Pupae Adults LT99 (minutes) 300 200 100 0 50 52 54 56 58 60 Temperature ( o C)

Fig. 2. •Confused flour beetle •Old larvae are heat tolerant 350 Eggs Young larvae Old larvae 300 Pupae Adults 250 LT 99 (min) 200 150 100 50 0 46 48 50 52 54 56 58 60 Temperature ( o C)

Effect of Humidity on Mortality of Red Flour Beetle Adults Effect of Humidity on Mortality of Red Flour Beetle Adults (KSU Pilot Flour Mill, Steam Heat Heat Treatment, March 17 Treatment, March 17- -20, 2000) 20, 2000) (KSU Pilot Flour Mill, Steam Exposure Temp. Hours to Hours % RH % Exposure Temp. Hours to Hours % RH % time reach 50 o C above 50 o C Mortality time reach 50 o C above 50 o C Mortality range ( o C) range ( o C) (hours) (hours) 24 22.1- -42.0 42.0 0.0 0.0 71.7 0.0 24 22.1 0.0 0.0 71.7 0.0 22.1- -42.0 42.0 0.0 0.0 58.6 0.0 22.1 0.0 0.0 58.6 0.0 22.1- -41.5 41.5 0.0 0.0 50.6 0.0 22.1 0.0 0.0 50.6 0.0 No 22.1- -41.5 41.5 0.0 0.0 30.7 1.7 No 22.1 0.0 0.0 30.7 1.7 Glycerol Glycerol G. 27.5- -28.3 28.3 0.0 0.0 36.2 1.7 G. 27.5 0.0 0.0 36.2 1.7 Chamber Chamber 47 47 22.1 22.1- -51.8 51.8 43.0 43.0 4.0 4.0 70.5 70.5 100.0 100.0 22.1- -51.8 51.8 43.0 4.0 57.5 100.0 22.1 43.0 4.0 57.5 100.0 22.1- -50.7 50.7 44.5 2.5 49.3 100.0 22.1 44.5 2.5 49.3 100.0 No 22.1- -51.2 51.2 44.0 3.0 26.2 100.0 No 22.1 44.0 3.0 26.2 100.0 Glycerol Glycerol G. 27.5- -28.7 28.7 0.0 0.0 37.1 0.0 G. 27.5 0.0 0.0 37.1 0.0 Chamber Chamber

Effect of Humidity on Mortality of Red Flour Beetle Adults Effect of Humidity on Mortality of Red Flour Beetle Adults (KSU Pilot Flour Mill, Steam Heat Treatment, March 17- -20, 2000) 20, 2000) (KSU Pilot Flour Mill, Steam Heat Treatment, March 17 Temperature = 50.1-52.4 o C; Growth chamber = 27.5 o C % RH, 20 Minutes 30 Minutes 50 Minutes % RH, 20 Minutes 30 Minutes 50 Minutes Range Range 53.6- -63.1 63.1 0.0 29.0 b 100.0 53.6 0.0 29.0 b 100.0 46.1- -49.3 49.3 0.0 93.8 a 100.0 46.1 0.0 93.8 a 100.0 31.6- -48.1 48.1 0.0 97.5 a 100.0 31.6 0.0 97.5 a 100.0 20.4- -20.5 20.5 0.0 95.0 a 100.0 20.4 0.0 95.0 a 100.0 No Glycerol No Glycerol 32.4- -38.1 38.1 0.0 0.0 c 0.0 32.4 0.0 0.0 c 0.0 Chamber Chamber For each time and treatment combination, n = 3.

Mortality of Red Flour Beetles Insulated by Mortality of Red Flour Beetles Insulated by Whole Wheat Kernels and Flour Whole Wheat Kernels and Flour (KSU Pilot Flour Mill, Steam Heat Treatment, November 23- -28, 28, (KSU Pilot Flour Mill, Steam Heat Treatment, November 23 1999) 1999) Commodity Location Temp. % RH, % Commodity Location Temp. % RH, % range ( o C) range Mortality range ( o C) range Mortality Wheat Top, 4” 21.7 - - 40.1 40.1 32.2 - - 81.4 81.4 9.5 Wheat Top, 4” 21.7 32.2 9.5 Middle, 14” 22.9 - - 40.1 40.1 26.2 - - 79.5 79.5 40.0 Middle, 14” 22.9 26.2 40.0 Bottom, 23” 22.9 - - 39.7 39.7 26.1 - - 80.2 80.2 25.0 Bottom, 23” 22.9 26.1 25.0 Flour Top, 6” 19.4 - - 38.8 38.8 27.9 - - 76.4 76.4 4.8 Flour Top, 6” 19.4 27.9 4.8 Middle, 14” 19.4 - - 38.9 38.9 27.6 - - 75.5 75.5 0.0 Middle, 14” 19.4 27.6 0.0 Bottom, 22” 19.8 - - 37.9 37.9 28.3 - - 70.6 70.6 0.0 Bottom, 22” 19.8 28.3 0.0

Apply a residual pesticide such as Tempo or diatomaceous earth

Why is sanitation alone not Why is sanitation alone not enough? enough? • Stored Stored- -product insects live for product insects live for • several months several months • They can survive on very little food They can survive on very little food • • 50% of the facility is inaccessible for 50% of the facility is inaccessible for • cleaning cleaning • Insects can seek out cool spots Insects can seek out cool spots •

Remove products and fumigate Remove products and fumigate to reduce risk of reinfestation reinfestation to reduce risk of Verify that the fumigation was Verify that the fumigation was successful successful

Should equipment be opened or closed? Should equipment be opened or closed? Open, clean, and then close Open, clean, and then close

Monitoring Insects Monitoring Insects • Before heat treatment, several weeks Before heat treatment, several weeks • • After heat treatment, several weeks After heat treatment, several weeks • • Identify species of importance Identify species of importance • • Degree of suppression Degree of suppression • • Duration of suppression Duration of suppression • • Use traps or take samples of products before Use traps or take samples of products before • and after heat treatment and after heat treatment • Results vary depending on whether traps or Results vary depending on whether traps or • products were used products were used

Monitoring Insects: Traps for Beetles Monitoring Insects: Traps for Beetles Flit- -Trak Traps Trak Traps Flit

Pherocon II traps for moths

1 2 30 30 25 A A 25 10 Distance from left front (m) 6 20 8 20 B B 6 4 15 15 4 10 10 2 C C 2 A A 5 5 A 0 0 A 0 0 Back room Back room 5 10 15 5 10 15 Distance from left front (m) Distance from left front (m) A=Wild bird food B=Small animal food C=Cat and dog food

8 C ryptolestes ferrugineus 6 Changes in mean number of insects captured in traps 4 2 0 1.0 15 C ryptolestes pusillus Sitophilus sp. 0.8 10 0.6 Number of adults 0.4 5 0.2 0.0 0 2.0 100 Tribolium confusum Tribolium castaneum 1.6 80 1.2 60 0.8 40 0.4 20 0.0 0 2.0 120 Total adults Trogoderm a variabile 100 1.5 80 1.0 60 40 0.5 20 0.0 0 7/18/00 8/1/00 8/15/00 8/29/00 9/12/00 7/18/00 8/1/00 8/15/00 8/29/00 9/12/00 D ate (m onth/day/year)

July 21-28, 1999 August 18-27, 1999 November 9-18, 1999 450.00 450.00 450.00 400.00 55.00 400.00 400.00 50.00 11.00 350.00 45.00 350.00 350.00 10.00 40.00 9.00 300.00 35.00 300.00 300.00 8.00 30.00 7.00 250.00 25.00 250.00 250.00 6.00 1.00 20.00 5.00 200.00 15.00 200.00 200.00 4.00 10.00 3.00 150.00 150.00 5.00 150.00 2.00 0.00 1.00 100.00 100.00 100.00 0.00 0.00 50.00 50.00 50.00 0.00 0.00 0.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 Before heat trt 1 After heat trt 1 Before heat trt 2 N KSU Pilot Flour Mill, mill floor - 1

Predictive Models Predictive Models • Need to generate data at constant Need to generate data at constant • temperatures in the laboratory temperatures in the laboratory • Uses temperature to determine Uses temperature to determine • mortality for any given temperature- - mortality for any given temperature time history time history

Nonlinear Relationship Between Survival of Nonlinear Relationship Between Survival of Old Larvae and Exposure Time at 46- -60 60 o C Old Larvae and Exposure Time at 46 o C 2.5 2.0 Log survival 1.5 46 o C 50 o C 48 o C 54 o C 1.0 0.5 58 o C 60 o C 0.0 0 50 100 150 200 250 300 Tim e ( t ), m inutes D ( ( T T ) is reciprocal of the negative slope averaged over time ) is reciprocal of the negative slope averaged over time D

Nonlinear Relationship Between Mean D ( T ) and Temperature Mean instant. D -value (minutes) 1000 y = 22.67 + 1.66*10 14 exp(-0.56* x ) n = 6; Adj R 2 = 0.95 800 600 400 200 0 44 46 48 50 52 54 56 58 60 62 Temperature ( o C)

The thermal death kinetic model was derived from the following equation N dt = − log ( ) t dt 10 N D ( T ) t t where N t-dt is the survival at t-dt time interval, N t is survival at time t N = 0 N ∆ t t ∑ t D ( T ) 0 t 10 where N t is number of larvae at time t ; N o is the original number of insects, ∆ t is the incremental exposure time (0.5-min), D is the mean instantaneous D -value as a function of temperature (T) , and T t is time- dependent temperature profile

Heating rate (1.09 o C/h) 120 120 N o 100 100 Number of insects Temperature ( o C) Temperature profile 80 80 N t Predicted population 60 60 T t Observed population 40 40 20 20 0 0 0 200 400 600 800 1000 1200 1400 1600 1800 Time (minutes)