Impact of Microwave heating on starch properties and texture in

sandwich bread Roua BouOrm12, Vanessa Jury12, Lionel Boillereaux12 , Luc Guihard12 and Alain Le-Bail12

1ONIRIS, BP 82225, 44322 Nantes, France 2UMR GEPEA CNRS 6144 - ONIRIS, 44307 Nantes, France

v Impact of heating mode on the evolution of Amylopectin Retrogradationand the formation of amylose-lipid Complexes during staling

o Microwave (MW) bread baking remains one of the most interesting alternatives due to its high volumic power, less baking time and its relatively low space demand.o MW baking was used to provide bread with less acrylamides, which can be considered as more “healthy” [1].Therefore, producing high-quality microwave- baked products

is a challenge for food technologists. Since starch is the main component of most baked goods, an in-depth understanding of the effects of MW on starch will play animportant role in improving the quality of “MW products”.

o The aim of this study was to compare the effect of MW baking andconventional baking:o on starch structure at different scaleo on staling in sandwich bread

v Moisture Content & Crumb Firminess Evolution

[1] S. Chandrasekaran, S. Ramanathan, and T. Basak, Microwave food processing-A review, Food Res. Int., vol. 52, no 1, pp. 243–261, 2013

Baking Heating Modes

Objectives Materials and Methods

Results

Conclusions

References

All analyses were performed in triplicate for each bread sample ( Center )

Conventional baked Crumb MW baked Crumb

The effect of different baking modes was analyzed at 7°C/min

Convection Microwave Oven ( Sharp Inverter )

- 230 watts 10 min

Conventional Oven(MIWE – deck oven)- 220°C for 20 min

0

0.5

1

1.5

2

2.5

3

3.5

4

1 6 14

Mel

ting

Enth

alpy

(J/g

dry

Fl

our)

Storage Period (Days)

H Class-6 °C/min

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

3 6 14

Mel

ting

Enth

alpy

(J/g

dry

Flo

ur)

Storage Period (days)

H 7°C/min - MW H 7°C/min - CV

P < 0.05 Vs.

Control

0

10

20

30

40

50

60

70

1 6 14

Moi

stur

e C

onte

nt (

g/10

0 g

d.m

.)

Storage (days)

0

1

2

3

4

5

6

7

8

9

1 6 14

Firm

ines

s (N

)

Storage (days)

üThe evolution of crumb firmness during storage was faster and the crumb was firmer in the case of MW baking compared to conventional baking

üMW produced a more homogenous heating with less baking timeüIncreased crumb firmnessüDisruption and Severe deformation of most starch granulesüFurther tests should be considered with faster heating ratesüOptimization of MW heating and Bread Recipe for industrial application

ü MW baking resulted in the formation of superficial cracks and granule deformation while in conventional baking, no ghost of starch granules were visible, the crumb being made of a continuous starchy gel with

very few granules remnants.

vStarch Granules Microstructure using ESEM in crumbs baked under diffrentheating modes

The 54th Annual Microwave Power Symposium

Drying cabinet : Moisture Content Réf. AACC method 44-15A (AACC, 1999)

SETARAM Micro-Calorimeter (MICRODSC-7)

Amylopectin retrogradation and amylose-lipid crystallization

Scanning Electronic MicroscopyStarch granules Microstructure

TA-XT TexturometerCrumb Hardness during Staling

The 54th Annual Microwave Power Symposium