Bäckerei- und Getreidetechnologie NanoBAK The NanoBAK technology Prof. Klaus Lösche, ttz BILB/EIBT...

Bäckerei- und Getreidetechnologie

NanoBAK

The NanoBAK technology

Prof. Klaus Lösche, ttz BILB/EIBT

Project 1st year meeting12th April – Holstebro/Denmark


Table of contents

1. Introduction

2. The NanoBAK System

3. The NanoBAK System - Ripening control with an optimal humidity in the atmosphere

4. The NanoBAK System – Humidity assisted cooling and freezing processes

5. Conclusions– Low energy and Premium quality


Table of contents

1. Introduction






Fuente: Chen. C.S., Lebensm.-Wiss.U. Technol., 18, 192-196, 1985

High energy demand

1. Introduction


• The ripening control:

retarded dough, interrupted dough, frozen dough.

• Bake-off processes:

par-baked and fully baked frozen products, pre-fermented dough, fully fermented and frozen dough, etc.

• Cooling after baking:

For packaging, for slicing, for post processing.

Current trends in bakery – fermentation control and frozen products

1. Introduction


Slow fermentation

Delayed fermentation

Interrupted fermentation

Deep-freezing

Control of the fermentation through less amount of yeast. It takes place at room temperature. Craft bakeries.

The fermentation speed is delayed through a quick decrease of the dough temperature.T range: +5°C to -6°C .

Interruption of the fermentation through a quick decrease of the dough temperature. T range: -7° to -18°C.

Long storage at lower temperatures than-18°C.

Maximum storage time: 8h.

Storage up to 72 h at aprox. 0°C, 80-85% RH.

Storage up to 72 h (90h) at aprox. -10°C, 80-85% RH.

Storage for several months Lower than -25°C, 75% RH

The fermentation process takes place during storage.

Final fermentation in a climatic chamber with optimal conditions depending on product.

Final fermentation in a climatic chamber: gradual change of temperature (1-2h, 3-10°C) followed by fermentation in optimal conditions depending on product characteristics.

Variations:DoughPar baked productsBaked products

Climatic chambers

1. Introduction


Cooling and freezing are high energy demanding processes and critical stages for the product quality

Conventional processingRel. Ambience H.= ~ 80-90 %

Desorption

Dough: Bread:Drying surfaces Freeze bruningIrregular products Weight losesWeight loses Undiserable colourUndesirable productCrust splitting

aW = 0,80-0,96(depending of it is dough or

bread)

Low cooling and freezing velocity

Skin formingHeterogeneous distribution of temperatureHumidity and temperature gradients

Low qualityHeterogeneous final products

Low conductivity

1. Introduction


Table of contents

1. Introduction

2. The NanoBAK Technology





Ultrasound based humidification system which generates a cold fog (mist) with water drops of around 1 micron

Cooling and freezing with assisted humidity

For assuring:

- High relative humidity in the chamber- Better humidity distribution (without sedimentation, without condensation)- Better conductivity- Saving yeast- and enzyme- activities in the surface- Less turbulences

Energy saving

2. The NanoBAK technology


Mollier h,x-Diagram

With a relative humidity of 70 % with +30°C 1kg air contains approx. 19g water

With a relative humidity of 75 % at +5°C , 1kg air contains approx. 5g water (retarder)



• Mechanical oscillations of the water surface that liberate the aerosol droplets

• Size of the water droplets depending upon the ultrasonic frequency (minimum 1MHZ), being down to 1 micron and generating a cold fog

• Mass-output, energetically efficient

The aerosol (~ 0.001 -0,005mm) is delivered by the air flow in the chamber and is distributed very fast and homogenously within the ambient air.

Piezokeramic transducer (Transducer, Schwinger)



0,1

1,0

10,0

100,0

1000,0

0 200 400 600 800 1000 1200 1400 1600

Droplet size [µm]

Fal

ling

sp

eed

[cm

/s]

10 30 60 100 250 500 750 1000 15000,303 2,68 10,2 27 94 210 313 400 545

Droplet size [µm]

sedimentation rate [cm/s]

Small drops have nearly no falling, float, can drift

Ultrasonic equipment: < 1,0µm electro-humidifier: > 50 – 150 µm

electro-humidifier

ultrasonic technology



An optimized humidity distribution in the chamber is achieved through the cold fog

Simulation of the humidity distribution in a climatic chamber with the MICROTEC system

Optimal humidity distribution




Without condentation problems


- Dried surface - Water loses and mass transfers (crust splitting)- Condensation on the surface- Sticky dough- Quality loses

-No drying effects, no condensation problems- homogenous Temperature and Humidity distribution- Water loses and mass transfer are minimized, so that the crust stress and consequently splitting is avoided- High quality products and low energy demand

aW = 0,89-0,96 aW = 0,89-0,96


Conventional processingRel. Ambience H.= ~ 80-90 %

NanoBAK technologyRel. Ambience H.= ~ 99 %

The improvement


Table of contents

1. Introduction






3. Case study: retarded fermentation

Remark: the temperatures depend on the chamber capacity and the size of the product, as well as on the design and production criteria.


expansion expansion

Conventional chamber Humidity assisted chamber

Retarded fermentation, T =+3°C, 16 hours





Retarded fermentation, T =+3°C, 16 hours


Conventional chamber

Hours

Crispiness retention

+Color

+ Crispiness

Conventional process

Humidity assisted

Humidity assisted chamber

Retarded fermentation: T = +3°C, 16 hours



3. Case study: interrupted fermentation

Remark: the temperatures depend on the chamber capacity and the size of the product, as well as on the design and production criteria.


Conventional chamberdough properties:sticky, wet and rough surface.

Humidity assisted chamberproperties:easily handling dough, humid inside but dry and smooth surface.

expansion expansion

Interrupted fermentation, T = -10°C, 20 hours



Conventional chamber

Humidity assisted chamber

Interrupted fermentation, T =-10°C, 20 hours



Conventional chamber with an electric humidifier (only able to work until +5°C) Energy consumption of the interrupted process, 20 hours= 44,40 KWh

Chamber with the humidity assisted system though cold fog (during the whole process)Energy consumption of the interrupted process, 20 hours = 27,80 KWh



High conductivity, better mass and heat transfer, faster browning:

Energy saving

Low conductivity, limited mass and heat transfer

Humidity assisted

Conventional process

Interrupted fermentation, T -10°C, 20 hours



Influence of the additional humidity on the enzymatic activity and/or the browning reaction (same baking conditions)

Decrease of the baking time



Interrupted fermentation, T =-10°C, 20 hours


Table of contents

1. Introduction






Conventional process: shock freezer

The freshly baked bread (previously cooled down) is frozen in a chamber at – 40°C (until -7°C on the core) and afterwards stored at -18 °C (or even -25°C)

Advantages:- Fast freezing

Disadvantages:- High energy consumption- Water loses up to 4%- Quality loses due to crust splitting- Freezer burn

4. Case study fully baked frozen bread


Crust splitting

- The crust splitting is evidenced after the freezing stage

- Part of the product surface is broken

- The storage of the product worst the problematic



a) Thermodynamic problem due to the temperature gradient

b) Gas pressure drop/ the gas bubbles contract

Hypothesis for the crust splitting problematic:

- Humidity diffusion to the cold crust- Condensation below the crust-Possibility of crystal formation below the crust-Expansion of ice will cause crust splitting

Congel.

Dry air

Source: Prof. Le Bail (ENITIAA, Francia)



Freezing process with additional humidity (at controlled intervals)

From 95°C until -10°C in the core (-20°C in the chamber), followed by storage at -18°C

Advantages:

- Better quality- Avoidance of water loses- Minimum crust splitting- Better conductivity = energy saving



Fully baked Baguette

Shock freezer immediately after baking (-40°C) until -10°C in the core followed by storage at -18°C (with packaging)

Fully baked Baguette

Humidity assisted freezing (-20°C) until -10°C in the core followed by storage at -18°C (with packaging)

Chamber at - 40°C Chamber at - 20°C, less energy consumption!



4. Case study: bread cooling

Adiabatic cooling


Step 1Adiabatic cooling with humidity contribution (discountinously) Freshly baked bread, from 95°C to +30 °C (core) (chamber at 20°C)Advantages:- Better final quality- No refrigeration system necessary, energy saving

Step 2Humidity asssisted freezing (interval)From 30°C up to -10°C in the core (chamber at -20°C)Advantages:- Better conductivity = energy saving- Better quality- Avoidance of the weight loses- Avoidance of the crust splitting and the freezer burn

Currently under study!



Figure 2: bread after 30 minutesIn a humidity assisted chamber at +1°C

Figure 1: bread after 30 minutesin a conventional chamber at +1°C

Case study: 1000g bread. Pictures taken using a thermograph after 30 minutes of cooling in a chamber at +1°C

27,3 °C 21,5 °C

Cooling process after baking



The product water loss during the cooling process can be avoided



Table of contents

1. Introduction






• Refrigeration technologies have enormously contributed to the growth, among others, of the bakery industry (starting by 1980/1985)

• Refrigeration technologies provide the bakery sector, both craft and industrial bakeries, with a great potential for innovation and development

• The way to optimal climatic techniques is driven by the final product quality and the energy demand

• The humidity assistance during the cooling and freezing stages improves enormously the current trendy processes and contributes to the energy reduction

• Optimal humidity conditions in the chamber and in the dough/bread are achieved

• Improvement of the bread and baked products quality: premium quality thanks to the humidity in the atmosphere

• At the same time, a significant energy saving can be achieved leading to an important reduction of costs

5. Conclusions – Low energy and Premium quality


Prof. Klaus Löschettz BILB/EIBT Am Lunedeich 1227572 BremerhavenTel. : +49 471 97297-13 Fax.: +49 471 97297-22

Vielen Dank für Ihre Aufmerksamkeit

Thank you for your attention


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Bäckerei- und Getreidetechnologie NanoBAK The NanoBAK technology Prof. Klaus Lösche, ttz BILB/EIBT...

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