Potato sloughing instrumental methods. for its assessment Anna Hejlová, Jiří Blahovec

Size: px

Start display at page:

Download "Potato sloughing instrumental methods. for its assessment Anna Hejlová, Jiří Blahovec"

Amie Parrish
5 years ago
Views:

1 Potato sloughing and instrumental methods for its assessment Anna Hejlová, Jiří Blahovec

2 Potato sloughing and instrumental methods for its assessment Cooked potato quality and texture profile Sensory methods for texture assessment CPM/CPW (cooked potato mass/weight) tests for sloughing assessment CPEM (cooked potato effective mass) method as modification of CPM tests CT (cooking time) and disintegration rate - new sloughing parameters Sloughing in different varieties in different cultivation conditions in relation to tuber density and starch content

3 Cooked potato quality Cooking/utilization types: A Salad potato B Fairly firm all-purpose C Mealy D Very mealy salad mash A B C

4 Potato texture profile Texture attributes: Mealiness Hardness/softness Sloughing Moisture/dryness Graininess/structure Sensory methods for its evaluation: Visually when crushed with a fork, 1= non-mealy, 7= very mealy The force necesssary to cut the wedges with a fork, 1=firm, 7=soft Visually according to pictures, 1=remaining whole, 7=completely disintegrated Orally, 1=moist, 7=dry Orally, 1=fine, 7= coarse

5 Potato sloughing flaking and disintegration of the outer layers of potato tubers cooked in water Sensory methods visually according to pictures of cooked tubers 1 = remaining whole, 7 = completely disintegrated Instrumental methods determination of cooked potato tissue amount separating in water bath remaining on the cooked sample

6 Standard CPM/CPW test (cooked potato mass/weight) potato sloughing assessment Potato sample cut from inner parenchyma 100 g, 10x10x1.5 mm Cooked and stirred decanted CPM value recorded cooking curve: CPM ~ t EAPR (European Association of Potato Research), Wageningen,1977

7 CPM cooking curves potato mass (g) cooked Panda CT = 11 min 100 Nicola CT = 32 min 100 Javor CT = 14 min 100 Direct correlation between CT 100 and cooking type was not found CT 100 < 4 min very sloughed CT 100 > 12 min non-sloughed EAPR: recommends as a complement to sensory tests cooking time (min) (Vacek, 1997) 100 g mass of the raw potato sample CT 100 (characteristic time) resistance against sloughing CPM cooking curve result of measurements

continuously during cooking The whole cooking curve

8 Modification: CPEM method Sample cooked and stirred on the sieve Cooked potato effective mass CPEM recorded continuously during cooking The whole cooking curve obtained in one test The sloughing can be studied in relation to tuber density

9 Sample preparation 3-4 tubers of the same flakes 10x10x1.5 mm size and densityρ(kg/m 3 ) potato sample = 100 g estimated by double weighing in air (m) and in water (m uww ) ρ = ρ water m / (m m uww )

cooker) 4 laboratory stand 5 analytical balance SCALTEC 6 immersion heater ( 1 kw) 7 stirring apparatus with metal

10 CPEM experimental set-up 1 glass beaker (5l, dia 180 mm) with a round metal sieve 2x2 mm placed 5 mm above the beaker bottom 2 polystyrene desk 3 screen basket (dia 150 mm, height 190 mm, diamond mesh 3x5 mm, part of a pasta cooker) 4 laboratory stand 5 analytical balance SCALTEC 6 immersion heater ( 1 kw) 7 stirring apparatus with metal propeller (VEB Prüfgeräte-Werk, Dresden, 1967) 8 metal propeller 9 NTC thermistor 10 digital multimeter 11 - stopwatch

11 Time schedule of the CPEM test Balance Data :00 :05 :10 Initial Screen Effective Mass Sample inserted Balance Data :00 :05 :10 :45 Balance Data :00 :05 :10 Pre-Heating 120 s working temperature Calming 40 s Heating 30 s Calming 30 s Heating 30 s Calming 30 s Heating 30 s Experiment time (min) t = -1 t = 0 t = 1

12 Recorded cooking curve and temperature Recorded balance data m bal (g) Sample insertion SEM initial screen effective mass t (min) 100,0 99,5 Initial test temperature 99,0 T ( C) 98,5 98,0 97,5 97,0 96, t (min)

Calibration and final CPEM cooking curve CPEM (g) 7 6 5 4 3 2 1 0-1 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 t (min) transformed CPEM curve = initial screen effective mass SEM subtracted change in SEM

13 Calibration and final CPEM cooking curve CPEM (g) t (min) transformed CPEM curve = initial screen effective mass SEM subtracted change in SEM final CPEM curve = change in SEM compensated Change of SEM (g) Calibration test without sample m = t , R 2 = t (min) Sample included m = t , R 2 =

14 CPEM cooking curve and parameters 7 CPE EM (g) SBP - Slope of the Breaking Part Cooking Part Breaking Part CT - Cooking Time t (min) CT cooking time required to start disintegration (min) SBP disintegration rate (g/min)

15 Sloughing in different cultivars SBP (g.min -1 ) 1,20 1,00 0,80 0,60 0,40 0,20 0,00 Sloughed Agria cooking type B crisps cultivation regimes Saturna mealy starch CT (min) Nicola cooking type BA salad Salad 7 6 CT cooking time required to start disintegration SBP disintegration rate 5 CPEM (g) SBP (g/min) CT (min) t (min)

16 Different cultivation regimes CT (min) SBP (g.s -1 ) F0 F1 W0 W F0 F1 W0 W1 F Fertilization, W Irrigation Agria Fertilization lower degree of sloughing Irrigation no significant influence on sloughing CT cooking time required to start disintegration SBP disintegration rate CPEM (g) CT (min) SBP (g/min) t (min)

17 CPEM parameters in relation to tuber density CT (min) 18 1, Nicola Saturna Agria SBP (g.min -1 ) 1,20 1,00 0,80 0,60 0,40 0,20 0,00 Agria Saturna Nicola ρ (kg.m -3 ) ρ (kg.m -3 ) higher degree of sloughing higher tuber density correlation between tuber density, dry matter and starch content Maercker s tables (1880) Scheele s formulas (1937) CT cooking time required to start disintegration SBP disintegration rate CPEM (g) CT (min) SBP (g/min) t (min)

18 CT (min) Agria Linear model of cooking stage I Nicola Saturna ρ (kg.m -3 ) CT ~ CT MV - b (ρ ρ MV ) b (min.m 3.kg -1 ) R CT-sensitivity to tuber density and starch content Cooking parameter typical for variety, independent of growing conditions ρ MV (kg.m -3 ) Density mean value of tested tubers Correlates closely with starch content CT MV (min) Cooking time mean value Characteristic of potato variety

19 Why does the cooked potato tissue disintegrate? Biological plant material Parenchyma cells Disintegration = potato cell rupture and/or separation Starch starch swelling pressure due to gelatinisation, comparable with turgor pressure Cell wall and middle lamella degradation of pectic polymers

20 CT (min) Agria Linear model of cooking stage II Nicola Saturna ρ (kg.m -3 ) CT ~ a CT0 - b (ρ ρ 0 ) b (min.m 3.kg -1 ) R CT-sensitivity to tuber density and starch content Cooking parameter typical for variety, independent of growing conditions ρ 0 (kg.m -3 ) Density of hypothetical potato tissue without starch Estimated as 1005 kg.m -3 (empirical formulas between density, dry matter and starch content - von Scheele) a CT0 (min) Time of cooking necessary to start disintegration of fictive potato tissue without starch Characteristic related to cell wall and middle lamella properties

21 CT (min) b (min.m 3.kg -1 ) Agria Linear model of cooking stage III Nicola Saturna ρ (kg.m -3 ) Agria+Saturna+Samantana a CT0 (min) Nicola CT ~ a CT0 - b (ρ ρ 0 ) b (min.m 3.kg -1 ) CT-sensitivity to tuber density and starch content a CT0 (min) Time of cooking necessary to start disintegration of fictive potato tissue without starch Characteristic related to cell wall and middle lamella properties The most varieties followed a common inner mechanism of cell tissue disintegration Divergent behavior of salad cultivar Nicola was observed

22 Conclusions CPEM method objective instrumental method for potato sloughing assessment reduces experimental material and operational time potato cooking properties can be studied in detail in relation to tuber density CT cooking time main parameter less than 6 min sloughed (type C) 6 14 min moderately sloughed (type B) more than 14 min slightly and non-sloughed (type A) improvement of experimental set-up possible

23 Publications Hejlová A., Blahovec J., Vacek, J. (2006) Modified test for potato sloughing assessment. Journal of Food Engineering 77(3), Blahovec J., Hejlová A. (2006) Role of Tuber Density in Potato Sloughing. Journal of Texture Studies 37, Hejlová A., Blahovec J. (2008) Sloughing in potatoes induced by tuber density and affected by variety. Czech Journal of Food Sciences, 26(1): Blahovec J. and Hejlova A. (2010). Simple Kinetic Models of Potato Sloughing, International Journal of Food Properties, 13(1): Hejlová, A. and Blahovec, J. (2010). The Modified CPEM (Cooked Potato Effective Mass) Method: an Instrumental Assessment of Potato Sloughing. Czech Journal of Food Sciences, 28(5): Current research: Blahovec, J., Hejlová, A., Čopíková J. and Novák, M. (2011). Tensile Properties of Microbial β-glucan Films. Polymer Engineering and Science, 51: Hejlová A., Blahovec J. (2015). Stress Relaxation and Activation Volume in Tension in β-glucan and Chitosan Films. Polymer Engineering and Science, 55 (3):

24 Thank you for your attention

» Croscarmellose Sodium is a cross linked polymer of carboxymethylcellulose sodium.

» Croscarmellose Sodium is a cross linked polymer of carboxymethylcellulose sodium. BRIEFING Croscarmellose Sodium, NF 22 page 2856 and page 702 of PF 30(2) [Mar. Apr. 2004]. A modification is made in the test for Degree of substitution to correct the endpoint color to agree with the