Cooking with Sound: Cream and Jam

Page 1

Principal Investigator Dr Carmen Torres-Sanchez, Research Lead Multifunctional Materials Manufacturing Lab

Sponsors


Motivation Food & Drink manufacturers are constantly looking for solutions to improve product quality, enhance nutritional properties and extend shelf-life. A reduction in energy consumption in their processes coupled with less waste will allow them to reduce their carbon footprint and meet the targets imposed by climate-driven national strategies to achieve net-zero.


Hypothesis Sonication is the use of ultrasound to aid emulsification and cooking processes. It is a technology that intensifies the aeration of blends and gives them long-term stability. It also enables cooking at lower temperatures while achieving the same chemico-physical reactions necessary to deliver the desired final product.


Sound λ = 0.5 m

Ultrasound 20 kHz

30cm

100 kHz

What is Ultrasound?

Infrasound

f = 1 Hz

Ultrasound

Audible Range

1 kHz

Imaging and Diagnostics

1 MHz


1.0 Cream Products


Case Study Emulsification of cream products has been aided with sonication Sonication has a documented effect on the development of bubbles in foams. Whipped cream is both a foam (a matrix of a liquid phase with dispersed gas bubbles) and an emulsion (a product containing liquid droplets (fat) dispersed in a second liquid phase (water)). Its stability is positively correlated to a larger resistance to deformation when stirred and to a lasting gas ‘hold-up’. The whipping of cream is a time-consuming, energy-hungry process, and dairy-free cream products are more difficult to process, creating more waste when the target texture is not achieved.

Cream

The study measured the variation of shear stresses (how much it deforms) in response to an increasing shear rate (how quickly the liquid phase is deformed) using flow curves. It also measured viscosity of the foam at different shear rates. Large values of shear stress and viscosity are indicative of a well-aerated product, a tight size distribution of droplets, a stable matrix and good levels of gas ‘hold-up’.


Cream Flow curves with an increasing then decreasing shear rate scale

Oscillation curves with an increasing shear stress 10,000

180

Viscous Modulus (GPa)

140 120 100 80 60 40 20

Viscous Modulus (GPa)

200 150 100 50

403.01

319.88

253.89

201.52

159.95

126.95

100.77

79.98

63.48

50.39

39.99

31.74

25.19

20.00

15.87

12.60

10.00

10

100.77

126.95

159.95

201.52

253.89

319.88

403.01

100.77

126.95

159.95

201.52

253.89

319.88

403.01

79.98

63.48

50.39

39.99

31.74

25.19

20.00

15.87

12.60

10.00

7.94

5.00

-0.001

0.008

0.032

0.137

0.579

10.297

43.421

13.590

3.223

0.764

0.181

0.043

0.010

0.002

0.000

2.442

Shear Stress (Pa)

Shear Rate (1/s) 1,000

100,000

900

Viscous Modulus (GPa)

600 500 400 300 200 100 0

10,000

1,000

100

Shear Rate (1/s)

79.98

63.48

50.39

39.99

31.74

25.19

20.00

15.87

12.60

10.00

7.94

6.30

5.00

-0.001

0.008

0.032

0.137

0.579

2.442

10.297

43.421

13.590

3.223

0.764

0.181

10 0.043

Shear Stress (Pa)

700

0.010

Cream

100

1

0.002

Power Level 3

1,000

6.30

Shear Stress (Pa)

8 min

10,000

0.000

Power Level 2

7.94

5.00

0.002

0.008

0.033

0.137

0.579

10.298

43.426

13.590

3.223

0.764

0.181

0.043

0.010

0.003

0.000

2.442

Shear Stress (Pa)

0

12 min

Power Level 1

10

Shear Rate (1/s)

800

Control

100

1

0

250

Results from rheological measurements at different whipping times while exposed to sonication (4, 8 and 12 min) and at different ultrasound intensities delivered via power level 1 (blue line), level 2 (red line) and level 3 (green line). An unsonicated, silent sample (control) prepared for the same duration is added for comparison (yellow dashed line).

1,000

6.30

Shear Stress (Pa)

Sonication improves foam stability with enhanced gas and droplet dispersions

4 min

160

Shear Stress (Pa)


Ageing An ageing study to 7 days of a sonicated cream shows that the emulsion is stable and sustains a good degree of gas ‘hold-up’ until day 7, when the bubbles coalesce. This is an improvement over the control sample with a typical shelf-life of 2-3 days.

Cream


Cream 2,500

Flow curves with an increasing then decreasing shear rate scale

Cream

0.002

0.008

0.032

0.137

0.579

2.440

10.291

43.393

13.588

3.223

0.764

0.179

0.043

0.010

0.009

1,000,000

Oscillation curves with an increasing shear stress

100,000 10,000 1,000 100 10

Shear Stress (Pa)

403.01

319.88

253.89

201.52

159.95

126.95

100.77

79.98

63.48

50.39

39.99

31.74

25.19

20.00

15.87

1 5.00

Day 7

Shear Rate (1/s)

12.60

Day 4

0

10.00

Day 3

500

7.94

Day 2

1,000

6.30

Day 1

1,500

0.000

Results from the ageing tests after 1 day (blue line), 2 days (green line), 3 days (red line), 4 days (yellow line) and after a week (pink line). The product was kept at a controlled temperature (4˚C) in a sealed container.

Viscous Modulus (GPa)

Sonicated creams have a longer shelf-life

Shear Stress (Pa)

2000


2.0 Jam Products


Case Study Preserving fruit is more efficient when aided with sonication Jam and Preserves cooking processes are very energy intensive because they require high temperatures and/or cooking over long periods of time. The producers of fruit products worry about the variability of the raw ingredients that arrive to the processing plant (ripeness, sugar and pectin levels) which affect final product texture. Fruit identity retained after the cooking process is another important quality control feature.

Jam

Raw materials can be very sensitive to temperature. Vitamins, probiotics, proteins and other active ingredients can be degraded due to over-exposure to heat, leading to a mismatch with the nutritional values reported on the label. Sonication allows a gentler cooking regime: it shortens the duration of the process and reduces cooking temperature, preserving nutritional values in the final cooked product.


Jam Temperature Profile

Sonication reduces cooking temperature and time

90

The maximum temperature reached is lower when the cooking is aided by sonication. This is important for the preservation of vitamins and to prevent deterioration of other nutritional ingredients.

70

The gelation point is reached sooner when sonicated. The product can be cooked for a shorter time to obtain the same results as in silent conditions.

80

Temp (°C)

60 50 40

Gelation point: shorter plateau and 30

quicker gelation when sonicated

20 10

Silent Sonicated

0 0

Jam

10

20

30

40

50

Time (min)

60

70

80

90

100


Jam pH Profile

3.8

Sonication eases pH control

3.7 3.6 3.5 3.4

pH

The acidity of the recipe changes during cooking. Sonication results in a gentler decrease in pH during cooking. The target range of pH values (2.8-3.2) is easier to control and predict. This is an advantage when there is variability in the ripeness of the raw fruit.

3.3 3.2 3.1 3

Silent Sonicated

2.9 2.8 0

10

20

30

40

Time (min) Jam

50

60

70

80


Jam Sugar Content Profile

75

Sonication makes sugar content easier to control

70

65

Brix %

The cooking of the fruit increases sugar content. In this study silent jams were sweeter than required. Sugar content (measured via %Brix) was moderated using sonication. The desirable range of %Brix values (65-68) was easier to achieve by the end of the process in sonicated preserves.

60

55

50 Silent Sonicated

45 0

10

20

30

40

Time (min) Jam

50

60

70

80


Pera International’s primary role is to facilitate research necessary to drive a sector forward, to fund generic R&D and to stimulate the establishment of collaborative research consortia to carry out the R&D. www.perainternational.com

Principal Investigator Dr Carmen Torres-Sanchez, Research Lead Multifunctional Materials Manufacturing Lab www.carmentorressanchez.wordpress.com @carmentorres www.linkedin.com/in/carmentorressanchez

One of the top 20 research-led universities in the country, Loughborough is renowned for the relevance of its work, driven by society’s need for solutions to real-life issues. www.lboro.ac.uk