Dry Transfer Inoculation of Low-Moisture Spices Containing Antimicrobial Compounds

Hildebrandt, Ian; Hu, Chuxuan; Grasso‐Kelley, Elizabeth M.; Ye, Peiran; Anderson, Nathan; Keller, Susanne E.

doi:10.4315/0362-028x.jfp-16-279

Cited by 23 publications

(5 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Every batch of microorganisms in SiO 2 can be dehydrated to the same a w level, regardless of the environmental variables present in individual laboratories. Similarly, sand (Blessington et al, 2013) and glass beads (Hildebrandt et al, 2017) were used in the same way, as they might have similar water sorption isotherms as that of SiO 2 .…”

Section: Sio 2 As An Inert Carrier In Dry Inoculation Methodsmentioning

confidence: 99%

“…This procedure may not be applicable to powdered foods and herbs, as sticking and agglomeration may occur (Wallack and King, 1988) and prevent uniform inoculation (Tamminga et al, 1977;Doyle et al, 1985;Nazarowec-White and Farber, 1997). Inoculating dry ingredients such as herbs and spices with a wet inoculum may also expose bacteria to water-soluble antimicrobial compounds (Shelef, 1984), which were observed to weaken bacterial cells before performing microbial studies (Hildebrandt et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dry inoculation methods for nonfat milk powder

Liu

Xie

et al. 2019

Journal of Dairy Science

View full text Add to dashboard Cite

Carriers with inoculated microorganisms are often used to validate low-moisture food safety interventions. In this study, we evaluated dry inoculation methods using silicon dioxide (SiO 2) and a small portion of nonfat milk powder (NFMP) as dry carriers for NFMP. Silicon dioxide was characterized by vapor sorption analysis. One milliliter of inoculum of a 5-strain Salmonella cocktail (serovars Agona, Reading, Tennessee, Montevideo, and Mbandaka) or Enterococcus faecium NRRL B-2354 was inoculated onto 1 g of SiO 2 or 10 g of NFMP as carriers. Both inoculated carriers were air-dried for 72 h [22°C, relative humidity (RH) ~30%], equilibrated to water activity (a w) 0.25 ± 0.02 (24 h at 22°C, RH 25%), and mixed with preconditioned NFMP (a w = 0.25 ± 0.02) to reach an inoculation level of 8.2 ± 0.2 log cfu/g. Inoculated NFMP was stored at 22°C, RH 25%, and its bacterial populations were monitored for 30 d. Both sets in equilibrated NFMP were subjected to isothermal treatments in closed aluminum cells at 85, 90, and 95°C. Silicon dioxide maintained moisture content (0.29 ± 0.03%, dry basis) at different water activities. The NFMP inoculated with both carriers exhibited stable bacterial populations over 30 d at 22°C. Strains in NFMP inoculated with SiO 2 showed equal or higher D-values but equal z-values compared with those inoculated with a small portion of NFMP. Enterococcus faecium exhibited comparable thermal resistance to Salmonella under all tested conditions. This study supports E. faecium as a Salmonella surrogate in thermal processing of NFMP and the use of SiO 2 to inoculate NFMP.

show abstract

Section: Sio 2 As An Inert Carrier In Dry Inoculation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dry inoculation methods for nonfat milk powder

Liu

Xie

et al. 2019

Journal of Dairy Science

View full text Add to dashboard Cite

show abstract

“…The inoculation method used in this study was shown to provide stable Salmonella populations in both types of milk powders prepared for thermal treatment. Different inoculation methodologies have been shown to significantly influence the thermal inactivation of Salmonella in low a w foods (Hildebrandt et al, 2016(Hildebrandt et al, , 2017Liu et al, 2019).…”

Section: Stability Tests Of Powder Inoculationmentioning

confidence: 99%

Effect of water activity on the thermal inactivation kinetics of Salmonella in milk powders

Wei

Lau

Chaves

et al. 2020

Journal of Dairy Science

View full text Add to dashboard Cite

Persistence of Salmonella in milk powders has caused several foodborne outbreaks. The determination of proper pasteurization processing conditions requires an understanding of the thermal inactivation kinetics of Salmonella in milk powders. However, there is a lack of knowledge related to the effects of water activity (a w ) and fat content on Salmonella inactivation in milk powder during thermal processing. Two types of milk powders, nonfat dry milk and whole milk powder, with different fat contents (0.62 and 29.46% wt/wt, respectively) were inoculated with a 5-strain cocktail of Salmonella and equilibrated to 3 a w levels (0.10, 0.20, and 0.30) for isothermal treatments at 75, 80, and 85°C to obtain D-values (the time required to achieve a 10-fold reduction of the bacteria at the isothermal treatment temperature) and z-values (the increase in temperature required to achieve a 90% reduction of the decimal reduction time D). Stability tests showed that the inoculation method used in this study provided a high and stable population of Salmonella for thermal inactivation studies. A moisture sorption isotherm was measured to understand the relationship between a w and moisture content of milk powders. The thermal resistance of Salmonella was found to significantly increase as a w decreased, which suggested that a higher temperature or longer processing time would be required at low a w to achieve the desired inactivation of Salmonella. The microbial inactivation kinetics were not significantly different for the 2 milk powders; therefore, data were combined to develop a universal model. A response surface model was compared with a modified Bigelow model. The modified Bigelow model performed well to predict D-values [root mean square error (RMSE) = 1.47 min] and log reductions (RMSE = 0.48 log cfu/g). The modified Bigelow model developed here could be used to estimate D-value as a function of water activity and temperature to design a thermal pasteurization system for milk powders.

show abstract

“…The TSA-grown cells methodology for preparation was simpler compared to dry inoculation or incorporation within the native biofilm methods. This inoculation method may have resulted in release of antimicrobial compounds (Hildebrandt et al, 2017), FIGURE 5 | Average log reduction in CFU/g of Salmonella enterica and E. faecium on cumin seeds processed using a lab scale vacuum steam pasteurizer chamber temperature 88 ± 5 • C, 97.9 kPa at different dwell times. Log reductions are the average of three independent runs and three technical replicates within run.…”

Section: Discussionmentioning

confidence: 99%

Inactivation of Salmonella enterica and Surrogate Enterococcus faecium on Whole Black Peppercorns and Cumin Seeds Using Vacuum Steam Pasteurization

Newkirk

Jian

Acuff

et al. 2018

Front. Sustain. Food Syst.

View full text Add to dashboard Cite

Spices, including black pepper and cumin seeds, have been implicated in outbreaks of salmonellosis and prompted recalls of ready-to-eat products containing contaminated spices. Vacuum-assisted steam pasteurization is performed to improve the safety and quality of many low water activity products, however process parameters associated with inactivation on whole spices are not well described. The objective of this study was to determine the effectiveness of a lab-scale vacuum-assisted steam process for the inactivation of Salmonella enterica and its potential surrogate Enterococcus faecium ATCC 8459 inoculated onto the surface of whole peppercorns and cumin seeds. In addition, the effect of two inoculation preparation methods [growth on tryptic soy agar (TSA) or inclusion within a native microbiota biofilm], on the reduction of S. enterica serovars or E. faecium was compared on steam pasteurized whole black peppercorns. Spices were processed using steam under a vacuum to achieve a mean product temperature of 86.7 ± 2.8 • C for different dwell times. Salmonella inoculated using the TSA-grown method, required 83 and 70 s respectively to achieve a 5-log reduction of Salmonella on peppercorns and cumin seeds. Longer time periods were needed to achieve a 5-log reduction of Salmonella when it was present in a native biofilm on whole peppercorns. Survivor estimations were best predicted by the Weibull models. The mean log reductions of E. faecium were 0.9 log CFU/g lower than Salmonella on whole black peppercorns inoculated using the TSA-grown cells (P = 0.0021). The mean log reductions of Salmonella and E. faecium prepared using the biofilm-inclusion method were not significantly different (P = 0.76). E. faecium log CFU/g reductions were not significantly different compared to Salmonella on whole cumin seeds (P = 0.42) indicating that while reductions are comparable the surrogate may not always provide a conservative indication of complete Salmonella elimination for all spices processed using vacuum-assisted steam. HIGHLIGHTS-E. faecium is a surrogate for Salmonella on steam processed whole black peppercorn.-E. faecium is not a conservative surrogate for Salmonella on steam processed >85 • C whole cumin.

show abstract

Dry Transfer Inoculation of Low-Moisture Spices Containing Antimicrobial Compounds

Cited by 23 publications

References 13 publications

Dry inoculation methods for nonfat milk powder

Dry inoculation methods for nonfat milk powder

Effect of water activity on the thermal inactivation kinetics of Salmonella in milk powders

Inactivation of Salmonella enterica and Surrogate Enterococcus faecium on Whole Black Peppercorns and Cumin Seeds Using Vacuum Steam Pasteurization

Contact Info

Product

Resources

About