Lethality Value Research Articles

Characteristics of Indonesian traditional food “Ayam Taliwang” and “Sate Rembiga” packed by retort process: F0 - value, metal contamination and microbial analysis

Abstract “Ayam Taliwang” and “Sate Rembiga” are traditional foods from Mataram, West Nusa Tenggara, Indonesia with meat-based ingredients and have a short shelf life. In this study, the packaging of ready-to-eat food products with a retort process to increase shelf life was explored. The main objective of this study was to identify the packaging results of Indonesian traditional food “Ayam Taliwang” and “Sate Rembiga” by retort process, including parameters of Lethality value (F0 -value), metal contamination and microbial analysis. The procedure of this study was that the food samples were packed in aluminum foil, then vacuum sealed and processed in a retort. The retort processing temperature and time used were 121°C and 20 minutes. The results showed that the F0-value for “Ayam Taliwang” was 19.62 minutes, while the F0-value for “Sate Rembiga” was 30.32 minutes. Metal contamination test results for “Ayam Taliwang” showed that Plumbum (Pb) was 0.531 ppm, Cadmium (Cd) 0.0047 ppm and Arsenic (As) 0.0317 ppm, while Mercury (Hg) and Lead (Sn) were not detected. The metal contamination test for “Sate Rembiga” was Cd 0.0013 ppm, As 0.0104 ppm and Sn 1.1621 ppm, while Pb and Hg were not detected. Microbial contamination test results for “Ayam Taliwang” showed that Staphylococcus aureus and Clostridium perfringens were 10 colonies/gr, Enterobateriaceae were 10 colonies/gr, while Salmonella and Lysteria monocytegens were negative. “Sate Rembiga”, Staphylococcus aureus and Clostridium perfringens were found at 102 colonies/gr, while Enterobateriaceae, Salmonella and Lysteria monocytegens were negative. Therefore, ready-to-eat “Ayam Taliwang” and “Sate Rembiga” meet the requirements for distribution using the retort process.

Efficacy of long-lasting insecticide-incorporated nets on 2 scolytinae pests, the coffee berry borer Hypothenemus hampei and tropical nut borer Hypothenemus obscurus under laboratory conditions.

Several pests affect coffee (Coffea spp., Rubiaceae) and macadamia, Macadamia integrifolia Maiden & Betche (Proteaceae) in Hawaii. The coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), is the most damaging to coffee, while the tropical nut borer, Hypothenemus obscurus (Fabricius) (Coleoptera: Curculionidae: Scolytinae), is one of the worst pests of macadamia. This paper investigates the potential efficacy of a long-lasting insecticide-incorporated net (LLIN) under laboratory conditions to manage these pests. The LLIN (40 denier with mesh size 625 knots/in²), incorporated with α-cypermethrin (0.34%), was excised into 100 mm circles and inserted in 100 mm Petri dishes. Nets with the same quality but without insecticides were used as control treatments. Twenty beetles (H. obscurus or H. hampei) each were placed on the treated and non-treated netting at 4 treatment or exposure hours-1, 6, 12, and 24-with 5 replicates. Subsequently, the beetles were ranked alive, affected, or dead. The results showed that the LLIN with α-cypermethrin had significant lethal and sub-lethal effects on both Hypothenemus species, causing over 90% mortality after 24 h of exposure and paralysis after 1, 6, and 12 h of exposure. The highest lethality value was recorded after 24 h of exposure for both H. obscurus and H. hampei. The LT50 of H. obscurus and H. hampei was 18.78 min and 2.15 h, respectively, while the LT90 values were 32.11 and 20.67 h. These results imply the potential effectiveness of LLINs with α-cypermethrin for management of H. obscurus and H. hampei, but field studies are warranted for optimization.

Early identification of “Gudeg” product characteristics in High Barrier Retort Grade (HBRG) packaging

Food packaging is needed to reduce the risk of food spoilage caused by physical, chemical, and biological factors. Based on the recent development, it is necessary to use a type of packaging that can be applied as food packaging while still having the durability to meet the feasibility level of the sterilization process. This study aims to identify the character of gudeg packaged with HBRG packaging procedure. In this study, the heat penetration, proximate and metal contamination analysis were done as an initial identification step for the characteristics of the gudeg in HBRG packaging. In this study, two variants of gudeg were made, namely egg gudeg and non-egg gudeg. The results obtained in this study are gudeg products packaged in HBRG packaging with a net product weight of 235 g per package. The lethality value of egg gudeg is 3.51 minutes and 4.94 minutes for non-egg gudeg. The energy value of non-egg gudeg and egg gudeg in HBRG packaging is 149.38 kcal/100g and 160.25 kcal/100g respectively. The metal contamination analysis being done in this study has stated that no heavy metal contamination was detected in all variants of products. HBRG packaging procedure can be applied for gudeg by following food safety requirements.

Ready-To-Eat Rice in Retort Pouch Packaging as an Alternative Emergency Food Product

Recently, the rising incidence of natural catastrophe has increased the disaster preparedness, aiming to mitigate its devastating effect. Developing an emergency food is one of meaningful attempts to rise the preparedness. This research aimed to determine the best formula of ready-to-eat rice in retort pouch packaging accepted by consumers, and to determine the operating time to reach a lethality value (F0) to meet the commercial shelf-stable food requirements as an emergency food. The thermal process adequacy (F0) was used to determine the commercial shelf-stable products according to Indonesian regulation. The results showed that the determination of ready-to-eat rice was dependent on the ratio of rice and water. The most accepted product was determined according to quality attributes and organoleptic tests applied to meet the criteria for emergency food, namely color, flavor, and texture and best perceived by consumers. A formula with 140 g of half-cooked rice and 60 g of water was attributed to the best sample, having hardness of 7305.45 gf, elasticity of 36.40%, gumminess of 2185.720 gf, and adhesiveness of -167.975 g.s. In terms of microbiological quality, the TPC for the half-cooked rice sample reached 7.2×107 CFU/mL, while cooked rice in retort pouch packaging was <25 CFU/mL. Using heat distribution curve, heating at 110°C produced a come up time (CUT) after 40 min. Furthermore, the F0 value was 4.12 which was in accordance with the Indonesian regulation.

Quality assessment of ready‐to‐eat Pacific saury (Cololabis saira) using microwave‐assisted thermal sterilisation combined with olive oil vacuum impregnation

SummaryAlthough microwave‐assisted thermal sterilisation (MATS) held great potential to sterilise ready‐to‐eat (RTE) products compared with traditional retort sterilisation, the quality improvement effect of MATS treatment on shelf‐stable RTE products has not been extensively studied. This study was performed to evaluate the efficacy and applicability of MATS combined with olive oil vacuum impregnation against lipid oxidation and microbial growth in RTE Pacific saury during storage. MATS combined with olive oil vacuum impregnation (MTSO) effectively reduced processing time (by 57%) compared to retort‐treated RTE Pacific saury at the same thermal lethality value. The lower cooking loss (6.19%) and colour damage indicated that MTSO enhanced water retention and the stability of tissue structure compared to retort‐treated group (9.88%) or no olive oil group (7.11%). Lipid oxidation and protein degradation were effectively inhibited in MATS groups compared to retort‐treated ones during storage; such effect was more effective in olive oil impregnated group. Likewise, microbial activity and electronic sensory evaluations showed that the shelf life of MTSO group was extended by 1 week compared to retort‐treated groups. Overall, MTSO had considerable industrial potential to yield RET Pacific saury and even RTE products with better quality attributes than retort‐treated ones.

Treated Cow Milk Quality Analysis in High-Temperature Short Time (HTST) Thermal Treatment using F-Value and Methylene Blue Reduction Test (MBRT)

This study was conducted to evaluate raw and pasteurized cow milk regarding physical properties, microbiological quality, and lethality value ofMycobacterium Paratuberculosis(MAP)at different temperature and time combinations of the pasteurization process.Cow milk samples were pasteurized at high-temperature (70°C, 75°C, and 81°C) and short-time (15s and 25s) high temperature and short time (HTST) combinations. Raw and pasteurized (HTST) cow milk was analyzed, while commercial cow milk that undergo proses (HTST) was used as control. High-temperature short time (HTST) pasteurization showed a significant effect on the colour of raw and pasteurized cow milk (p<0.05) at every temperature. In addition, cow milk also indicated an increase in lightness and yellowness after HTST pasteurization.The microbiological quality of raw, pasteurized, and commercial cow milk is evaluated using the Methylene Blue Reduction (MBRT) test, a common, rapid, simple, and inexpensive method for microbiological quality evaluation.The MBRT on raw milk samples revealed that it was of poor quality. On the other hand, all pasteurized samples were good quality, and the commercial sample was excellent.Based on the evaluated F-values, the most suitable temperature and time combinationsin this study was 70°C and 25s.

Comprehensive investigation into quality of pasteurized Oncorhynchus keta Walbaum fillets and non-thermal effects of microwave

Microwave processing is a novel technology in shortening food processing time and improving product quality. These advantages are achieved through the thermal and possible non-thermal effects of microwave. The main objective of the study was to explore the non-thermal effects of microwave electromagnetic (EM) fields on quality traits of pasteurized Oncorhynchus keta Walbaum fillets. A single-mode microwave processing system processed the fillets with a pasteurization thermal lethality value of F90 = 10 min. Corresponding pasteurization process with synchronous heating was designed to match the time-temperature profile of microwave processing. Retort pasteurization was used as a conventional process to compare the fillet quality performance with microwave pasteurization. With the pasteurization thermal treatment level, the proportion of six free amino acids was significantly different (P < 0.05) between the microwave pasteurized fillets and synchronous heating pasteurized fillets. The result could be attributed to the non-thermal effects of microwave EM fields. Compared with the retort pasteurization, the microwave process performed better in overall quality. Results suggested that microwave pasteurization exerted non-thermal effects in individual quality traits and caused less damage to fillet quality than the retort process in overall quality.

Self contained Food Sample Homogenization Filter Bag for Microbial Analysis

The complexity of food materials owing to the diverse matrices and biochemical composition poses challenge to microbiologists especially to identify the microbial contamination at low level. The present study describes the development and evaluation of a ready to use self-contained food sample homogenization bag (All-In-Bag) with the required sterile diluent and an in-built filter for subsequent clarification of the homogenate for microbiological analysis. Three-ply non-foil laminate comprising outer alumina oxide coated polyester film, middle nylon and inner polypropylene layers were used for the outer layers while non-woven polypropylene sheet with of 50 μ to 100 μ size porosity was sandwiched between the laminated sheets to restrain the food debris but allow the microbial cells to pass through across along with the diluent. The homogenization bag along with the diluent was sterilized by thermal (retort) processing with F0 value (lethality value) of 12 to ensure the sterility of diluent during storage. The effectiveness of the All-in-Bag for the homogenisation of different food sample matrices for microbiological analysis was compared with BagPage®+ bag. All-in-Bag withstood the shearing action during sample paddling in the bag mixer/stomacher and no significant difference was observed for both aerobic plate count. Spike and recovery of E. coli from the different food matrices indicating absence of interference for microbial recovery in newly developed All-in-Bag. The All-in-Bag, the first of its kind with 12 months shelf life does away with the requirement of sterile diluent preparation and additional steps for the clarification of the homogenate and thus making microbial food quality analysis easier in places with limited resources.

공기 중 폭발에 의한 함정의 손상반경 간이 계산식 개발

To decide a separation distance of the redundant vital equipment in a naval ship, the damage radius due to an aerial explosion should be estimated. In this research, a simplified formula for the damage radius has been developed by using existing empirical formulae for reflected shock pressure and shock lethality value of equipment. As a numerical example, the damage radius for a typical pump aboard a naval ship has been calculated by the developed formula and compared with the results calculated by Measure of Total Integrated Ship Survivability (MOTISS) which is one of survivability analysis codes verified, validated and accredited by the US Navy. Also, comparison with the results calculated by existing other simplified formulae has been made.

Non-thermal effects of microwave processing on inactivation of Clostridium Sporogenes inoculated in salmon fillets

Microwave processing has been a promising technology in improving quality and ensuring microbial safety of food products, while non-thermal effects of microwave is in controversy. The objective of this study was to investigate the non-thermal effects of microwave electromagnetic (EM) fields on Clostridium Sporogenes (surrogate of Clostridium botulinum) inoculated in salmon fillets using same time-temperature profiles method. The inoculated salmon fillets were processed by a single-mode pilot microwave processing system with different radiation time (2, 3 and 4 min) and holding time (0, 2 and 4 min). Corresponding water bath treatments were designed for each microwave processing to obtain matching time-temperature profiles. Results showed that the same time-temperature profiles method was successfully achieved to evaluate the microwave non-thermal effects in salmon fillets. With equal or lower thermal lethality value, microwave processing brought significantly higher (P < 0.05) reduction values than water bath treatment. This determined the non-thermal effects of microwave EM fields. And the non-thermal effects increased with longer microwave radiation time and was intensified by higher temperature. However, the following holding section will weaken the additional inactivation efficiency of microwave non-thermal effects. Results suggested that microwave processing could provide better bacteria control with lower thermal processing level.

Lethality Calculation of Particulate Liquid Foods during Aseptic Processing

In the past two decades, aseptic processing has been implemented in the food industry to sterilize particulate liquid food mixtures. To ensure that particulates in the liquid receive sufficient heating, mathematical modeling is employed to evaluate the temperature and lethality level in the particles. We developed a model for the thermal processing of liquid foods containing cubic particles in a continuous laminar pipe flow system, comprising a tubular heat exchanger. In our simplified approach, heat transfer equations for particulate liquid foods were solved analytically and numerically to evaluate the effect of certain process parameters on the time temperature profiles of particles and the lethality value in the products. A comparison of the particles’ lethality values was made between the experiment and simulation for two different particle residence times in a case study, and the model predictions were in good agreement with experimental data. Based on modeling studies, it was found that within the range of parameters studied, an increase in flow rate and particle size resulted in a decrease in the lethality value of the particles, while an increase in particle concentration and holding tube length resulted in the opposite effect.

Anticancer activities of toxic isolate of Xestospongia testudinaria sponge.

Aims:The purposes of this study were to determine the anticancer activity of Xestospongia testudinaria sponge isolate and identify the responsible compounds.Materials and Methods:The metabolites were extracted using methanol maceration at room temperature. The separation and purification of metabolites were performed using fractionation and column chromatography. The toxicity was examined using the brine shrimp lethality assay, and the toxic isolates were tested for anticancer activity against HeLa cells. Gas chromatography-mass spectrometry analysis was used to identify the compounds in the isolate.Results:When the methanol extract was partitioned with n-hexane, chloroform, and n-butanol, the chloroform fraction was the most toxic, with a concentration that results in 50% lethality (LC50) value of 39.81 ppm. After separation of the chloroform extract, fraction B (FB) was the most toxic, with an LC50 value of 44.67 ppm. The isolate from FB showed anticancer activity with a concentration at which 50% of growth was inhibited (IC50) of 2.273 ppm. In total, 21 compounds were identified in anticancer isolates: Nonanedioic acid; tetradecanoic acid; trans-phytol; 2-pentadecanone-6,10,14-trimethyl; pentadecanoic acid; 2-hexadecen-1-ol, 3,7,11,15-tetramethyl-; pentadecanoic acid; 2-hexadecen-1-ol, 3,7,11,15-tetramethyl-; 2,3,7-trimethyloctanal; palmitic acid; docosanoic acid, ethyl ester; 1,E-11,Z-13-octadecatriene; chloromethyl 4-chlorododecanoate; 1-tricosene; 9,12-octadecadienoic acid; 4,8,12,16-tetramethylheptadecan-4-olide; 1-docosene; heneicosane; phosphonic acid, dioctadecyl ester; dodecane,4,6-dimethyl-; n-tetratriacontane; 1-iodohexadecane; and n-heneicosane.Conclusion:These findings indicate that the isolate of X. testudinaria can be used as a natural anticancer toward HeLa cell.

A Cytotoxic Activity of Tahongai (Kleinhovia hospita Linn.) Leaves Extracts Using Brine Shrimp Lethality Test

Tahongai (Kleinhovia hospita Linn.) leaves had been known contain alkaloids, flavonoids, saponins, steroids, and tannins. At Komering, South Sumatera tribe, tahongai leaves had been known to treat tumor, cancer, polyps, acne, and dysmenorrhea. The study of cytotoxic activity of tahongai bark and stem were done. This study aims to determine the cytotoxic activity of tahongai leaves extracts using BSLT method. Tahongai leaves were extracted using gradual maceration with n-hexane, ethyl acetate, and ethanol 96%. Each extract was tested cytotoxic activity towards Artemia salina L. larvae. The yield of n-hexane, ethyl acetate, and ethanol extracts are 2,686%, 7,033%, and 7,933% respectively. Ethanol extract of tahongai leaves had the best cytotoxic activity with lethality value 76,667% at 500ppm. Statistical analysis with two way ANOVA showed extract and concentration had a significant (p&lt;0,05) effect on larvae lethality percentage.

Comparative analysis of temperature loggers used in the development of regimes for heat treatment of food production in autoclaves

Heat treatment processes carried out in an autoclave at a temperature from 60 up to 130 °C are usually applied in the canned food production. Actual process lethality value is used as a criterion determining the product readiness and its microbiological safety. It is computed by summing the lethal effect values of heating obtained at different temperatures recorded inside the tin can with product. Loggers (thermographs) are special technical means of temperature measurement and recording in an electronic storage device, used to automate the task of obtaining product temperature kinetics. The article provides a comparative analysis of the widespread Thermochron DS1922T (used in the Thermochron protector capsule) and Ellab TrackSense PRO loggers, which protection class allows working in conditions (water, high temperatures and pressure) specific for typical heat treatment product regime. The logger Ellab TrackSense PRO was accepted as an etalon. Loggers recorded the temperature at the least heated point of the autoclave sterilization chamber during all processes. The graphs of temperature kinetics for pasteurization and sterilization processes were received in series of experiments. Thermochron thermographs absolute and relative errors, declared by the manufacturer, are experimentally verified. In result, the conclusion and recommendations of thermal recorder Thermochron DS1922T utilization are given.

Physicochemical Properties and its Relations of Beef Rendang inside Retort Pouch Packaging in Various Temperature Storage Conditions

Physicochemical characterization for beef Rendang inside retort pouch packaging had been evaluated. The objective of this study was to know the effect of time, and temperature storage to the physical properties of beef Rendang includes interactions between them so it could be evaluated what properties were changed along storage. Commercially sterile beef Rendang products using sterilization process at a pressure of 1.3 bar for 40 minutes holding time with the lethality value (Fo) of 4.67-7.49 minutes were stored at three different temperatures (35, 45, and 55 °C). Moisture content, pH, and rancidity value (TBA) as physicochemical properties examined were observed for 6 weeks of storage. The results showed that the effects of three different temperatures and times storage had significant difference value of moisture content, pH, and TBA value. Moisture content, pH, and TBA value of beef Rendang were approximately in the amount of 38-42%; 5.15 – 5.38; and 0.12 – 0.27 mg malonaldehyde/kg sample respectively, along 6 weeks of storage.

Investigating the influence of pH and selected heating media on thermal destruction kinetics of Geobacillus stearothermophilus (ATCC10149)

Geobacillus stearothermophilus is a thermophilic spore-forming bacterium which is used for intense thermal process validations (10 min–15 min). Several factors including the pH and heating medium influence the heat resistance of such microbial spores. In this study, the influence of using different buffer types including McIlvaine and phosphate was compared to distilled water at pH 7. Also, the effect of pH variations was studied using McIlvaine buffer at pH 3, 4, 5, 6, 7, and 8. All kinetics studies were conducted at 110 to 120 (°C). Results showed higher heat sensitivity (higher Z value) in distilled water (8.27 °C) than in phosphate (9.21 °C) and McIlvaine buffers (9.59 °C); likely being influenced by the high percentage of inorganic salts present in these buffers. The spores had the highest heat resistance at neutral pH, and the associated D values decreased both below and above pH 7.0. The pH effect on enhancing the heat sensitivity was higher at 110 °C, but the overall temperature influence was not significantly different (p > 0.05). Further, both first-order and Weibull models were compared for thermal destruction kinetics of G. stearothermophilus. Results demonstrated some concavity in the log-linear survival curves suggesting a slightly better fit for the Weibull model in some cases, but the model did not show any better prediction than the first-order model for a 3D lethality (Fo) value of 15 min. The combined effect of pH and temperature also showed cubic trends, and the Ea ranged between 240 and 398 (kJ) at pH 4–7.

Development and quality evaluation of retort processed RTE functional gluten free foxtail millet halwa

The present study focuses on the replacement of wheat and the development of ethnic RTE Indian products. Gluten, a protein complex present in wheat, causes celiac disease and gluten sensitivity in people. Foxtail Millet is one such cereal, which can be substituted for wheat due to its availability and nutritional importance. Halwa is a delicious sweet dessert rich in fat and carbohydrates, which is prepared mainly in North India. Through retort processing, the shelf life of halwa can be increased to make these products available for an increased period. The RTE foxtail millet halwa was prepared and retorted to the total lethality value of 5.26 minutes. Retorting has significantly reduced the total microbial population and much less physico-chemical changes were recorded after processing, when compared to the control. The retorted products were stored under refrigerated and ambient conditions and the changes in physico-chemical properties were evaluated. During the storage period, the shelf life study revealed that there were much less significant changes in the physico-chemical properties under both storage conditions. Though, there was a comparatively equal amount of changes occurring in both the refrigerated storage and ambient storage conditions, the appearance and texture of the products stored in ambient storage conditions rather than in refrigerated conditions were found to be good...

Shelf life prediction of canned fried-rice using accelerated shelf life testing (ASLT) arrhenius method

Research on shelf-life prediction of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius model has been conducted. The aim of this research to predict shelf life of canned-fried rice products. Lethality value of 121°C for 15 and 20 minutes and Total Plate count methods are used to determine time and temperatures of sterilization process.Various storage temperatures of ASLT Arrhenius method were 35, 45 and 55°C during 35days. Rancidity is one of the derivation quality of canned fried rice. In this research, sample of canned fried rice is tested using rancidity value (TBA). TBA value was used as parameter which be measured once a week periodically. The use of can for fried rice without any chemical preservative is one of the advantage of the product, additionaly the use of physicalproperties such as temperature and pressure during its process can extend the shelf life and reduce the microbial contamination. The same research has never done before for fried rice as ready to eat meal. The result showed that the optimum conditions of sterilization process were 121°C,15 minutes with total plate count number of 9,3 × 101 CFU/ml. Lethality value of canned fried rice at 121°C,15 minutes was 3.63 minutes. The calculated Shelf-life of canned fried rice using Accelerated Shelf-life Test (ASLT) of Arrhenius method was 10.3 months.

Assessment of Heavy Metal Induced Organ Toxicity in marketed Ayurvedhic Formulation and Report its LD50 value with Brine Shrimp Lethality Assay

Ayurvedhic system of medicine is an ancient and traditional medicine of India. These preparations use combination of remedies to alleviate diseases. Heavy metal poisoning in ayurvedhic preparation contribute to 0.6% of global burden for diseases. Children consuming this estimated to contribute about 6, 00, 000 of newer intellectual disabilities every year. Previously the ayurvedhic preparations were available as bhasmas and they are incorporated with adjuvant heavy metals to increase the potency. Heavy metals often found are lead, arsenic and mercury. Lead interferes with many bodily function affecting brain, lungs, liver and kidney. Arsenic causes keratosis, gangrene; cancer in skin, kidney, bladder and lungs after 20 yrs. Mercury is a neurodevelopmental poison affecting cell migration causing cell degeneration and death. In modern formulations their presence may be excessive because of poor quality control, contamination, adulteration and improper purification. Therefore users of ayurvedhic formulation are at risk of developing heavy metal poisoning leading to organ toxicity. In this study a selective herbal formulation were subjected to estimate for their heavy metal content and its lethality value is found by carrying out with brine shrimp lethality assay.

Effects of Packaging Geometry on Heat Penetration Time in Retortable Semi-Rigid Plastic Trays

Semi-rigid, retortable trays were filled with a food simulate and thermally processed in a water immersion automated batch retort system at rotational speeds of 6 RPM and 11 RPM. Triangle, rectangle, oval, and round trays were evaluated, each having approximately the same overflow capacity. During processing, trays were fixed in place with racks containing one shape per rack. Various rack location combinations were tested to provide processing data for each shape in each rack location. Heat penetration data was gathered using thermocouples located in the geometric center of each tray shape and this data was modeled to determine the slowest heating container. No differences were observed in rack location among tray geometries at either RPM level (P>0.05). The data generated during heat penetration runs was also used to model different retort temperatures and lethality values. A retort temperature of 215°F and a lethality value of 10 showed the highest average sterilization time (P 0.05) than any other shape tray. At a rotational speed of 11 RPM, differences in average process time to reach lethality between tray geometries were insignificant (P>0.05).