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 Factors affecting the composition and 
quality of broccoli juice 
 
 
A thesis presented in partial fulfilment of the 
requirements for the degree of 
Master of Technology 
in 
Food Technology 
at Massey University, Palmerston North, New Zealand. 
 
 
Claire T Petersen Redman 
2009 
 

i 
 
 
Abstract 
A shelf life trial using a fully balanced factorial experimental design was used to analyse the 
effects of acidity and light on broccoli juice made on a semi commercial scale over an eight 
week period in simulated retail refrigerated storage conditions. The research focused on 
making broccoli juice on a pilot scale, and what happens to the colour, composition and 
flavour during storage.  
A pilot scale production of pasteurised broccoli juice was conducted and the juice satisfied 
microbiological safety limits for the eight week shelf life trial in retail storage conditions. The 
stability of the green colour of fresh broccoli through processing and storage was assessed. 
Neutral broccoli juice remained green for four weeks before the colour became more yellow. 
The acidified juice became yellow on acidification and did not change significantly during 
storage.  
Dietary fibre and pectin levels did not change during storage. Chlorophyll and carotenoids 
levels decreased during storage and were directly influencing the colour changes in the juices. 
Ascorbic acid levels decreased significantly during processing resulting in low ascorbic acid 
levels (12 - 15 mg /100ml of juice) at the start of the shelf life trial and dropped further to 2-6 
mg /100ml of juice after eight weeks. Acidification and storage in the dark had a protective 
effect on the degradation of ascorbic acid with only a 58% reduction in ascorbic acid levels 
compared to an 84% reduction in neutral light stored broccoli juice.  
The effect of processing and storage on the flavour of the beverage was assessed using a 
trained sensory panel providing descriptive analysis. The sensory profiles for neutral and 
acidified juices were extremely different with the unbalanced acidity suppressing the 
perception of the basic tastes, sweet, salty and bitter.  The neutral juice sensory profile only 
changed slightly in aroma attributes during storage for seven weeks. The astringent aftertaste 
of the acidified juice increased while the broccoli smell decreased during storage. 
The results from this research indicate that the production of a broccoli juice with a yellow 
green colour and some retained nutritional components is achievable with a refrigerated (4 °C) 
shelf life of 30 days in light excluding glass packaging. The neutral juice is recommended as it 
was greener and had a broccoli flavour.  
ii 
 
 
Acknowledgements 
I would like to thank my supervisors, Drs Marie Wong, Erin O’Donohgue and Lee Huffman, for 
their advice, patience, guidance and support throughout this project.  
Gratitude goes to Plant and Food Research (formerly Crop and Food Research). Their financial 
support and investment in my research made this possible.   
To my colleagues Carl Massarotto, Shiji Nair, Virginia Corrigan, Allan Hardacre, Suzanne Clark, 
Rebecca Zou and Annie Teoh for their tolerance, helpful advice and support.  
I would like to extend my appreciation to:  
Erin O’Donohgue and Sheryl Somerfield for their help and guidance with the analytical testing 
and HPLC analysis and scientific rigor. 
Garry Radford and Warrick Johnson at Institute of Food Nutrition and Human Health (IFNHH) 
Palmerston North for their support and help taming the UHT equipment, Malcolm Reeves from 
EIT for the use of the water press and Kapiti Green Ltd for the generous supply of broccoli. 
Duncan Hedderly and Andrew McLaughlan for their help and guidance with the statistical 
analysis. 
Virginian Corrigan and John Grigor for their advice on the sensory training, assessment and 
analysis and to the sensory panellists for their dedicated efforts. 
Ann-Marie Jackson, Laboratory services manager, School of Engineering and Advanced 
Technology, Massey University, and Weiping Liu, Laboratory Technician, IFNHH, Massey 
University for the microbial analysis. 
Lastly but my biggest thanks go to my family for their patience and tolerance, support and 
sacrifice, especially Stuart and little Jessica whose life to date has revolved around broccoli 
juice.   
  
iii 
 
 
CONTENTS 
Abstract ......................................................................................... i 
Acknowledgements ...................................................................... ii 
List of Tables ................................................................................ v 
List of Figures .............................................................................. vii 
Chapter 1 ........................................................................................... 1 
Introduction .................................................................................. 1 
Chapter 2 ........................................................................................... 3 
Literature review ........................................................................... 3 
2.1 Broccoli ....................................................................... 3 
2.2 Juice production ....................................................... 13 
2.3 Juice safety .............................................................. 23 
2.4 Juice visual quality .................................................... 26 
2.5 Juice flavour perception ............................................ 31 
2.6 Summary .................................................................. 33 
Chapter 3 ......................................................................................... 34 
Materials and Methods ............................................................... 34 
3.1 Juice Production ....................................................... 34 
3.2 Shelf life trial conditions and experimental design ..... 41 
3.3 Juice analysis ........................................................... 45 
Chapter 4 ......................................................................................... 58 
Preliminary experiments ............................................................. 58 
4.1 Acidification .............................................................. 58 
4.2 Pasteurisation ........................................................... 61 
Chapter 5 ......................................................................................... 66 
Shelf Life Trial Results and Discussion....................................... 66 
5.1 Introduction ............................................................... 66 
iv 
 
 
5.2 Processing factors .................................................... 67 
5.3 Standard juice properties .......................................... 70 
5.4 Composition .............................................................. 77 
5.5 Colour ....................................................................... 87 
5.6 Sensory Evaluation ................................................... 93 
Chapter 6 ....................................................................................... 102 
Discussion ................................................................................ 102 
6.1 Pilot scale production of broccoli juice .................... 102 
6.2 Broccoli juice in a retail environment ....................... 103 
Chapter 7 ....................................................................................... 114 
Conclusions and recommendations .......................................... 114 
7.1 Conclusions ............................................................ 114 
7.2 Recommendations .................................................. 115 
References ............................................................................... 116 
Appendix .................................................................................. 125 
 
 
 
  
v 
 
 
List of Tables 
Table 2.1 Composition of raw Broccoli (Brassica oleracea var. italica) (Athar et al. 2006; 
FSANZ 2009; USDA 2009) Carbohydrate, (a: by difference, b: available carbohydrates). 
5 
Table 2.2 Intrinsic and Extrinsic microbial growth factors (Jay 1996; Bari et al. 2005). 25 
Table 3.1 Resources used for juice production. 35 
Table 3.2 Experimental plan for acidification per 100 g of juice of raw broccoli juice. 37 
Table 3.3 Experimental plan for heat treatment optimisation of neutral and acidified broccoli 
juice pasteurised for 15 sec. 
38 
Table 3.4 Description of juice required for analysis for each type. 44 
Table 3.5 Equipment used in biochemical assays. 47 
Table 3.6 Enzymes, chemicals and reagents used in biochemical assays. 48 
Table 3.7 Attributes, descriptions and references for neutral and acidified broccoli juice. 55 
Table 4.1 The pH, titratable acidity and °Brix of raw broccoli juice acidified with increasing 
amounts (% w/w) of ascorbic acid or citric acid. 
60 
Table 4.2 Colour measurements of lightness, chroma and hue angle for raw broccoli juice 
acidified with increasing concentrations (% w/w) of ascorbic acid or citric acid. 
61 
Table 4.3 Microbiological test results for neutral and acidified broccoli juice pasteurised for 
15 sec at specified temperatures.  
63 
Table 4.4 Microorganism lethality calculations.  64 
Table 4.5 Titratable acidity (g/100ml citric), soluble solids (°Brix) and total chlorophyll 
(mg/ml) content in neutral and acidified broccoli juice pasteurised for 15 sec at three 
different temperatures. 
65 
Table 4.6 Colour measurements, lightness, chroma and hue angle for neutral and acidified 
broccoli juice pasteurised for 15 sec at different temperatures. 
65 
Table 5.1 Broccoli juice yield. 68 
Table 5.2 Composition of neutral and acidic broccoli juice for the shelf life trial.  68 
Table 5.3 Dry matter (g/100ml) of broccoli juice treatments during storage time at 4°C.  70 
Table 5.4 Microbiological test results for raw (un-pasteurised) neutral and acidified broccoli 
juice. 
71 
Table 5.5 Microbiological test results for neutral and acidified broccoli juice sampled 
according to the shelf life trial experimental design in Section 3.2. 
73 
Table 5.6 pH values of broccoli juice treatments following storage at 4°C for the times 75 
vi 
 
 
indicated. 
Table 5.7 Titratable acidity (g citric acid /L) of broccoli juice following storage at 4°C for the 
times indicated. 
76 
Table 5.8 Soluble solids (°Brix) of broccoli juice treatments following storage at 4°C for the 
times indicated. 
77 
Table 5.9 (mg/100ml) total chlorophyll, chlorophyll a and chlorophyll b for broccoli juice 
treatments over storage time at 4°C.  
84 
Table 5.10 ANOVA significant difference (p values) of total chlorophyll, chlorophyll a and 
chlorophyll b for all neutral or acidified broccoli juice treatments. 
84 
Table 5.11 Colour values for neutral and acidified broccoli juice in light or dark storage over 
and eight week period. 
90 
Table 5.12 Summary of significant attributes from ANOVA for neutral broccoli juice 
treatments. Significance = p<0.05. 
98 
Table 5.13a Summary of significant attributes from ANOVA for acidified broccoli juice 
treatments. Significance= p<0.05. 
101 
Table 5.13b Summary of significant attributes from ANOVA for acidified broccoli juice 
treatments. Significance= p<0.05. 
102 
 
  
vii 
 
 
List of Figures 
Figure 2.1 A broccoli plant with the outer leaves removed before harvesting. 6 
Figure 2.2 L-ascorbic acid (AA) and its oxidised form dehydro-L-ascorbic acid (DHAA)(Anon 
2009d). 
8 
Figure 2.3 Glucosinolate breakdown process (Fahey et al. 2001). 9 
Figure 2.4 Structure of pectin (Anon 2009e). 12 
Figure 2.5 Structure of chlorophyll a and chlorophyll b (Anon 2009d). 29 
Figure 2.6 Structure of carotenoids β-Carotene and lutein (Anon 2009d). 31 
Figure 3.1 Process flow diagram and pictorial for the production of broccoli juice. 40 
Figure 3.2 Shelf life trial full balanced factorial experimental design for refrigerated (4±1°C) 
storage time in retail lighting conditions. After set time periods juice was frozen at -20±2°C 
until the experiment was concluded and analyses commenced.  
42 
Figure 3.3 Intensity scale for rating neutral and acidified broccoli juice.  56 
Figure 5.1 Total dietary fibre content (g/ 100ml broccoli juice) for broccoli juice treatments 
over storage time at 4°C. Data are presented as means ± SE (n=3). 
78 
Figure 5.2 Pectin content (mg/ml) for broccoli juice treatments over storage time at 4°C. 
Data are presented as means ± SE (n=3). 
80 
Figure 5.3 Ascorbic acid (mg/ml) for broccoli juice treatments over storage time at 4°C. Data 
are presented as means ±SE (n = 3). 
81 
Figure 5.4 The change in mean total chlorophyll content (mg/100ml) of broccoli juice 
treatments over storage time at 4°C. Data are presented as means ±SE (n=3). 
83 
Figure 5.5 Total carotenoids (mg/100ml) for broccoli juice treatments over storage time at 
4°C. Data are presented as means ±SE (n=3). 
87 
Figure 5.6 Photos of broccoli juice shelf life trial treatments.  89 
Figure 5.7 Lightness values for broccoli juice treatments over storage time at 4°C. Data are 
presented as means ± SE (n=6). Values relate to the difference in lightness, with 0 black and 
100 = white. 
92 
Figure 5.8 Chroma values for broccoli juice treatments over storage time at 4°C. Data are 
presented as means ± SE (n=6). Values increase in purity of hue from 0. 
92 
Figure 5.9 Hue angle values for broccoli juice treatments over storage time at 4°C. Data are 
presented as means ± SE (n=6). 60° = yellow, 120° = green. 
93 
Figure 5.10 ∆E the total colour difference for broccoli juice treatments over storage time at 
4°C. Data are presented as means ± SE (n=6). 
93 
viii 
 
 
Figure 5.11 Spider plot of the sensory profiles of neutral and acidic reference broccoli juices. 95 
Figure 5.12 Spider plot of the means for neutral broccoli juice over storage time in weeks. 
Data is means of duplicate assessments and trained panellists (n=24). 
96 
Figure 5.13 Spider plot of the means for acidified broccoli juice over storage time in weeks. 
Data is means of duplicate assessments and trained panellists (n=24). 
99 
Figure 5.14 Shelf life trial summary of trends. 105