Improving the Microbial Safety of Wheat Flour through non-thermal Pre-Milling Interventions - PowerPoint Presentation

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Improving the Microbial Safety of Wheat Flour through non-thermal Pre-Milling Interventions

Luis E. Sabillón

The Food Processing Center

University of Nebraska – Lincoln

Low-moisture ingredient It cannot support the growth of microorganisms Bacterial contaminants may survive in a dormant state until they reach environments that are more receptive to growth Validated kill step during processingMicroorganisms are destroyed during baking or cookingProduct safety relies on the consumer to perform this stepConsumers often disregard package instructions and warnings

Misconceptions about flour food safety

Conditioning is a routine processEnhance the efficiency of flour extractionIt influences the microbial load of milled productsIt can be used as a tool to improve the microbiological quality of wheat grains prior to milling Current approaches:Chlorine (milling industry) OzoneNovel tempering solutions

Wheat conditioning

Overall objective Improve the microbiological quality of wheat milling-end products through non-thermal pre-milling interventionsSpecific objectives Evaluate the effectiveness of organic acids and saline solutions as antimicrobial treatments for wheat during conditioning Examine the influence of the stages of milling process on the microbiological quality of milled productsDetermine the effect of tempering solutions on the functional properties in both white flour and whole-wheat flour

Objectives

Whole-grain flour

Straight-grade flour

Enumeration before

conditioning

A

PC, Yeasts, Molds,

Enterobacteriaceae

Enteric pathogens

Incoming

wheat

Tempered wheat

Tempering

solutions

15.5

% moisture

24

hr

holding period

1%, 2.5%, 5% Organic acids

1%, 2% NaClCombinations

Enumeration

24hr

after

conditioning

Buhler experimental mill

Enumeration

Enumeration

Functionality tests

Materials and Methods

Specific objective # 1

Reducing microbial load through conditioning

Natural microbial flora

Natural microbial flora

Natural microbial flora

Natural microbial flora

Enteric pathogens

Specific objective # 2

Microbial redistribution caused by milling process and additional effect of this novel tempering in the mill

Microbial distribution during milling

Microbial load of wheat flour

Whole-grain flour

Microbial load within the mill

Specific objective # 3

Effects on flour functionality

Titratable acidity

Treatments

Flour pH

(SD

)

Acidity ml 0.1N NaOH (SD)Control (Water)5.74 (0.04)a1.50 (0.28)cLactic acid 2.5% - Salt 1%5.73 (0.02)a1.43 (0.06)cLactic acid 5.0% - Salt 1%5.58 (0.01)b1.60 (0.00)cAcetic Acid 2.5% - Salt 1%5.45 (0.02)c2.00 (0.00)bAcetic Acid 5.0% - Salt 1%5.28 (0.02)d2.28 (0.04)a

TreatmentsFlour pH (SD)Acidity ml 0.1N NaOH (SD)Control (Water)6.25 (0.02)a1.53 (0.07)eLactic acid 2.5% - Salt 1%5.79 (0.02)b2.90 (0.00)dLactic acid 5.0% - Salt 1%5.51 (0.05)c4.23 (0.15)bAcetic Acid 2.5% - Salt 1%5.74 (0.01)b3.16 (0.06)cAcetic Acid 5.0% - Salt 1%5.41 (0.02)d4.59 (0.02)a

Whole-Grain Flour

Straight-Grade Flour

Flour starch properties

P

asting

Peak viscosity

Final viscosity

Setback

Breakdown

Flour starch properties

P

asting

Peak viscosity

Final viscosity

Setback

Breakdown

Mixing properties of wheat flours

Treatments

Peak time (Minutes)Peak height (%)Right slope (%/Minute)Straight-Grade FlourWater 5.75a 49.36b -1.08aLA 2.5% + Salt 1% 5.58ab 51.55a -0.52aLA 5.0% + Salt 1% 5.29ab 53.18a -1.23aAA 2.5% + Salt 1% 4.97b 52.31a -0.43aAA 5.0% + Salt 1% 5.23ab 52.41a -1.16aWhole-Grain FlourWater 4.48b 45.33a -0.88aLA 2.5% + Salt 1% 4.61ab 45.85a -1.42aLA 5.0% + Salt 1% 5.05ab 45.56a -1.42aAA 2.5% + Salt 1% 4.68ab 45.58a -1.05aAA 5.0% + Salt 1% 5.32a 45.95a -1.58a

Conclusions

Implementation of

organic acids and salt

in tempering water

prior to milling

could benefit the milling industry and consumers by

reducing the risk of microbial contamination

in milled products.

Consistent

use of this process would ensure

more sanitary milling

operations

by preventing microbial establishment and growth within the mill; therefore,

reducing the risk of post-processing contamination

during milling.

Thank you

Questions or comments?