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Resolving problems affecting the processing of dried marrowfat 

peas for fried foods:   

Hard-seededness and cooking temperature and time 

 

 

A thesis 

submitted in partial fulfilment of the requirements 

for the degree of 

Masters of Food Technology 

 

 

 

Massey University 

Palmerston North, New Zealand 

 

 

 

Froilan T. Ayaquil 

 

 

September 2017 



 

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ABSTRACT 

 

The Midland Seed Ltd, a top agricultural seed producer in New Zealand, wishes to 

increase their level of technical knowledge regarding the processing of peas to assist with 

solving production problems. In this study, analyses were conducted to resolve if hard-

seeded peas or the frying parameters caused the textural irregularities in fried marrowfat 

peas. Marrowfat peas (pisum sativum cv. Midichi and Midlea) from 16 different harvest 

locations and years (2014 to 2017) were subjected to tests such as hydration capacity, and 

sizing of peas were examined to ascertain how much hard-seeded peas were surfacing in a 

line batch and in different sizes (<6.7mm, 6.7-7.1 mm, 7.1 – 8.0 mm, and > 8.0mm) upon 

soaking (in different soaking times 12, 18 and 24 hours) and frying at 160°C for 12 minutes. 

Furthermore, frying conditions including, oil temperature, pea to oil ratio, were explored at a 

laboratory scale to obtain the most suitable frying parameters capable of producing fried 

marrowfat peas with consistent and highly acceptable organoleptic properties. It can be 

concluded from this study that the very low frequency of hard seeds found in marrowfat peas 

was not the cause of texture inconsistency generally.  However, it was shown that cooling 

the oil to below 130°C, when peas were added to the oil, slowed temperature recovery of the 

oil and significantly increased pea hardness to unacceptable levels. Marrowfat peas fried at 

160°C for 12 minutes, with a pea to oil ratio of between 1/20 and 1/40 resulted in peas 

consistently fried to a highly acceptable quality. 

 

  



 

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ACKNOWLEDGEMENTS 

First of all, I would like to thank our Lord Jesus Christ for giving me an opportunity to do this 
research project and Master’s programme.  

I would also like to thank the New Zealand Ministry of Foreign Affairs and Trade and New 
Zealand Aid Development program for offering the opportunity and scholarship support to 
the whole Master’s program. 

Massey University International Student Support Support Office Sylvia, Dave, Jamie, Logan, 
Dianne, Tina, and Saba; they are our second family here in New Zealand, and have never 
stopped caring for us. 

Midland Seeds Ltd, Brett Colgan and Krystyna Krivanek, for the research opportunity, trust, 
and support. 

Allan Hardacre, for his constant guidance, support, great advice in academic and personal 
life, and his limitless patience especially in checking my writing.  

I would also like to thank: 

Steve Glasgow, Warwick Johnson, Michelle Tamehana, Peter Jefferies, Sue Nicholson, 
Byron McKillop, Gary Radford, Chris Hall, Michael Parker for their technical assistance and 
support in my study. 

Ericka Ramirez and Edgar Santos for helping me in analysing my data and statistics. 

Ruth Mortimer for proofreading and guiding me.  

Sunny George Gwanpua, for his help and his mini-lecture to enable me to understand the 
topic easily. 

My colleagues, Grace Ng, JieHong, TeckAnn, Zitong, Maheeka, Jessie, Peter, Zhenghao, 
Echo for sharing each other’s lives in dealing with the struggles and challenges of 
postgraduate studies. 

My friends Dominic Lomiwes, Spencer Secretario, Marc Icaro, Tracy Decena, Fem Socorro, 
Marvin Novio, Kaye Nono, Francis and Joanna Vattiprolu, and Vision Church for the 
unending support encouragement and great memories. 

Our family, friends and relatives, Dr. Rosario Sagum , Tito Ansel and Tita Nenita Leonardo 
and family, Tito Ron and Babe Icaro and family, and Ayaquil, Tec and Cuico family.  

And especially to my wife and life partner, Michelle Cuico, her never ending patience, 
support and love the keeps me going and reaching for success. 

  



 

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TABLE OF CONTENTS 

ABSTRACT ........................................................................................................................... iii 

ACKNOWLEDGEMENTS ..................................................................................................... iv 

TABLE OF CONTENTS ........................................................................................................ v 

LIST OF FIGURES ............................................................................................................... v 

LIST OF TABLES .................................................................................................................. ix 

CHAPTER 1: INTRODUCTION ............................................................................................. 1 

Objectives ......................................................................................................................... 3 

General Objective .............................................................................................................. 3 

Specific Objectives ............................................................................................................ 3 

CHAPTER 2: LITERATURE REVIEW ................................................................................... 4 

2.1 LEGUMES AND PULSES ........................................................................................... 4 

2.1.1 Structure of legume seed ...................................................................................... 5 

2.1.2 Composition of legumes ........................................................................................ 6 

2.1.3 Nutritional benefits of legume consumption ........................................................... 8 

2.2.4 Quality standards and evaluation of pulses ......................................................... 10 

2.2.5 The hard seed phenomenon in legumes ............................................................. 12 

2.2 PEAS .................................................................................................................... 18 

2.2.1 Garden and field peas ......................................................................................... 18 

2.2.2 Growth and development .................................................................................... 19 

2.2.3 Adaptation ........................................................................................................... 20 

2.2.4 Pea seed structure and function .......................................................................... 21 

2.2.5 Pea size grading ................................................................................................. 23 

2.2.6 Current use and possible opportunities for peas ................................................. 23 

2.2.7 Marrowfat peas ................................................................................................... 23 

2.3 SOAKING AND COOKING ........................................................................................ 25 

2.4 FRYING ..................................................................................................................... 25 

2.4.1 Effects of frying ................................................................................................... 26 



 

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CHAPTER 3: MATERIALS AND METHODOLOGY ............................................................ 28 

3.1 MATERIALS .............................................................................................................. 28 

3.2 GENERAL METHODOLOGY .................................................................................... 30 

3.2.1 PHYSICAL TEST METHODS .............................................................................. 30 

3.2.2 MOISTURE CONTENT ....................................................................................... 30 

3.2.3 TEXTURE ........................................................................................................... 30 

3.2.4 DATA ANALYSIS ................................................................................................ 31 

CHAPTER 4: HYDRATION AND HARD-SEEDED PEAS ................................................... 32 

4.1 INTRODUCTION ....................................................................................................... 32 

4.2 MATERIALS AND METHODOLOGY ......................................................................... 32 

4.2.1 Sizing of peas ..................................................................................................... 32 

4.2.2 Hydration capacity ............................................................................................... 32 

4.3 RESULTS AND DISCUSSION .................................................................................. 34 

4.4 CONCLUSION........................................................................................................... 38 

CHAPTER 5: FRYING OF PEAS ........................................................................................ 39 

5.1 INTRODUCTION ....................................................................................................... 39 

5.2 MATERIALS AND METHODOLOGY ......................................................................... 39 

5.2.1 Analysis of benchmark samples .......................................................................... 39 

5.2.2 Effect of frying temperature and time................................................................... 39 

5.2.3 Frying peas at different frying loads..................................................................... 40 

5.2.4 Frying of different batches (line number) of marrowfat peas ................................ 41 

5.2.5 Frying of peas soaked in different salt solutions .................................................. 41 

5.3 RESULTS AND DISCUSSION .................................................................................. 42 

5.3.1 Analysis of benchmark samples .......................................................................... 42 

5.3.2 Effect of frying temperature and time................................................................... 43 

5.3.3 Frying peas at different frying loads..................................................................... 47 

5.3.4 Soaking solutions ................................................................................................ 50 

5.4 CONCLUSION........................................................................................................... 51 

CHAPTER 6: STARCH AND PROTEIN .............................................................................. 52 



 

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6.1 INTRODUCTION ....................................................................................................... 52 

6.2 MATERIALS AND METHODS ................................................................................... 52 

6.2.1 Protein Content ................................................................................................... 52 

6.2.2 Starch Isolation ................................................................................................... 53 

6.2.3 Pasting Properties of Pea Starch ........................................................................ 54 

6.3 RESULTS AND DISCUSSION .................................................................................. 54 

6.4 CONCLUSION........................................................................................................... 56 

CHAPTER 7: OVERALL CONCLUSION ............................................................................. 57 

CHAPTER 8: RECOMMENDATIONS ................................................................................. 58 

REFERENCES ................................................................................................................... 59 

APPENDIX A ...................................................................................................................... 64 

APPENDIX B ...................................................................................................................... 67 

  

 

  



 

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LIST OF FIGURES 

Figure 1 Seed Structure of (a) French Bean and (b) Pea         5 

Figure 2 Hydration rate of marrowfat peas stabbed, split and normal peas     14 

Figure 3 Percent moisture uptake of whole and dehulled HTC pinto beans    15 

Figure 4 Percentage moisture uptake (dry basis) of ETC (Rose Coco) and HTC (Pinto) 

beans             16 

Figure 5 Effect of soaking on (A) ETC and (B) HTC beans      17 

Figure 6 Hydration rates of faba beans soaked at different pH levels    17 

Figure 7. The pea seed          21 

Figure 8 Seed coat layers of Wild Pea (Pisum elatius)      22 

Figure 9 Dried marrowfat peas         29 

Figure 10 Texture Analyzer - 25 mm flat cylinder attachment     31 

Figure 11 Soaking marrowfat peas in water        33  

Figure 12 Size distribution of marrowfat peas       34 

Figure 13 Hydrated marrowfat peas (MF1644)        35 

Figure 14 Frying oil temperature log for different frying loads      49  



 

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LIST OF TABLES 

Table 1 Nutrient composition of pulses, wheat and maize (in %, dry basis)       6 

Table 2 Thermal properties of starch from different pulses and corn        8 

Table 3 Micronutrient composition of pulses, wheat and maize (in %, dry basis)       9 

Table 4 Quality parameters commercial quality pulses        10 

Table 5 Quality parameters identified by IPQC         11 

Table 6 Type of peas, seed characteristics and colour of cultivar       19 

Table 7 2014 – 2017 Marrowfat peas line number and location      28 

Table 8 Sample of marrowfat peas from different dressing processes     29 

Table 9 Hard-seeded peas and water absorbed of different marrowfat peas’ sizes    34 

Table 10 Hard-seeded peas at different soaking times of 2016 marrowfat pea lines   35 

Table 11 Percentage of hard-seeded peas from different harvesting locations    36 

Table 12 Water absorbed of marrowfat peas (2017) in different soaking times    37 

Table 13 Water absorbed of marrowfat peas from the seven dressing processes    37 

Table 14 Moisture content, volume and break force of different benchmark samples   42 

Table 15 Moisture content, volume and break force of fried peas (MF1638A) 160°C   43 

Table 16 Comparison of moisture, volume and break force of benchmark samples and 

laboratory fried peas            44 

Table 17 Moisture content and texture of marrowfat peas fried at different temperatures and 

time              45 

Table 18 Fried peas yield and quality defects after frying       46 

Table 19 Different pea batches fried at 160°C for 12 minutes      47 

Table 20 Peas fried at different frying loads         48 

Table 21 Correlation between physicochemical properties of dried and fried marrowfat peas

              50 

Table 22 Moisture content and texture of fried (160°C, 12 min) marrowfat peas with 

treatment in soaking solutions          51 

Table 23 Protein of normal peas and hard-seeded peas       54 

Table 24 Pasting properties of marrowfat peas starch       55