Biology Experiment: Investigating Apple Browning Process and Solutions

This assignment details a biology experiment designed to investigate the enzymatic browning of apples and the effectiveness of various solutions in slowing down this process. The experiment involved slicing apples, immersing them in different solutions (sprite, oil, vinegar, and a control), and observing the time taken for browning to reach a specific color scale. The experimental design included two factors: solution type and condition (covered vs. not covered). The results were analyzed using ANOVA, Tukey's test, and Fisher LSD, revealing significant effects of both solution type and condition on the browning rate. The analysis also included diagnostic checks of assumptions and statistical comparisons between the means of different treatments. The study concluded that both the type of solution used and whether the apple slices were covered influenced the browning time, providing insights into potential methods for preserving the appearance of cut apples.

1.0 Introduction - 1 ppl
1.1 motivation of the project
Apple is a sweet and edible fruit grown on an apple tree. Consuming apples
have a lot of health benefits such as lower risk of diabetes, good for heart, good for weight
loss, have prebiotic effects, prevent cancer and more (Kerri, 2018). Thus, apples were
commonly consumed daily. However, when the apple was cut or bruised, the apple flesh will
eventually turn brown. It looks ugly and suspected unsafe to eat but this was only the
misconception of general people. The brown apple is perfectly safe to eat. The cause of this
change is enzymatic browning. When the apple cells have been destroyed, polyphenol
oxidase(PPO) enzymes and phenolic compounds that keep separately suddenly mix together,
and react with the presence of oxygen. The brown pigment came from the product of this
chemical reaction called melanin (Amanda, 2013). Even the color change is harmless to
human health, most people still wish to remove the unapealing brown colour on apples. Thus,
we choose to carry out this experiment to determine the effective way to slow down the
enzymatic process.
1.2 objectives of the experiments
To determine the time taken for browning reaction happened till a certain level
of brown intensity on the apple was observed after soaking in different solution for 30
seconds.
2.0 Methodology - 1 ppl
2.1 Experimental design
Two Le Crunch France Royal Gala red apples were bought from Econsave in
Kampar. Next, an apple was cut into eight slices with similar sizes to ensure that each
of the slices had the same thickness. The apple slices were put into four cups, each
cup contains two slices. Three different types of solution which were sprite, oil and
vinegar were added into the four cups respectively, remaining one cup was left as
empty. The solution was put higher solution level than the apple slices to make sure
that each of them were fully immersed. After immersing the apples into the respective
solution for 30 seconds, one slice of the apples was taken out from each cup and was
put into four cups with covered respectively. At the same time, the remaining slices of
apples from the four cups were taken out and transferred into another four cups
without covered. The stopwatch was started and the time needed for the browning of
apples were recorded. The experiment was repeated again with another apple after all
the data from the first apple were collected.

Figure 1. Eight slices
of apple were
immersed into
respective types of
solution for 30
seconds.
Figure 2. Four slices of apples were put into four cups with
covered while another four slices of apples were transferred into
four cups without covered after immersing the apple slices in the
respective solution for 30 seconds.
2.2 Choices of factors and levels
For choices of factors, there are two factors in this experiment which are solution
types and condition. The factor level for the solution types are 1(nothing), 2(sprite),
3(oil), and 4(vinegar) while for the factor level of condition, there are only two factor
levels which are A (covered) and B (not covered). Thus, there are a total of eight
treatments in this experiment which are 1A, 1B, 2A, 2B, 3A, 3B, and also 4A, 4B.
2.3 Selection of response variable
The response variable of this experiment is the time needed for the browning
effect (in minutes) to occur on apple slices. To determine the browning effect, a
colour scale for browning of an apple is used as below. After discussing among group
members, we decided to use scale 3 as the color scale for browning. Once any of the
1cm x 1cm area of the apple slice achieved the scale 3 color scale, the time needed for
the browning effect was recorded.
Figure 3. Color scale used to determine the browning of apple slices.

2.4 Numbers of replication
For the number of replication, there are only two replicates since we did the
experiment two times using the another apple.
2.5 Experimental unit
The experimental unit is the two Le Crunch France Royal Gala red apples as we
assigned them to the treatments.
2.6 Statistical Analysis
The experiment was performed according to a full factorial design (solution
type x condition) and subjected to an analysis of variance (ANOVA). The effect
model is yijk = μ + αi + βj + αiβj + εijk. This equation used is describing the effect of
solution type and condition, the combined effect of solution type and condition, and
the interaction effect of solution type and condition on the time needed for the
browning effect (in minutes) to occur on apple slices. To determine the optimum
conditions the residual plot and normal p-p plot between solution type, condition and
time needed for the browning effect (in minutes) to occur on apple slices were
generated.
3.0 Result and Discussion - 3 ppl
3.1 Statistical model
Table 1. Time needed for the Browning effect (in minutes) to occur on apple slices.
Solution
Type
Condition
A B
1
70 44
75 50
2
100 48
128 60
43 41

3 41 23
4
20 34
24 20
* Key: A=covered, B=not covered
a=4, b=2, n=2 (Help for confirm) correct
3.2 Analysis of variance (ANOVA)
yijk = μ + αi + βj + αiβj + εijk
yijk: Time needed for the Browning effect (in minutes) to occur on apple slices
μ: Overall mean
αi: Effect of type of solution i
βj: Effect of type of condition j
αiβj: Interaction effect
εijk: Random error
Anova: Two-Factor With
Replication
Source of Variation SS df MS F P-value F crit
Solution type 8253.69 3 2751.229 28.7898
4
0.000123 4.066181
Condition 2047.56 1 2047.563 21.4264
2
0.001691 5.317655
Interaction 2327.69 3 775.8958 8.11925 0.008233 4.066181
Error 764.5 8 95.5625
Total 13393.44 15
*α = 0.05
H0: All αi = 0
H1: Not all αi = 0
F crit = 4.0662, F = 28.7898
F > F crit, reject H0.

∴There is sufficient evidence to conclude that the solution type will affect the time needed for
the Browning effect (in minutes) to occur on apple slices.
H0: All βj = 0
H1: Not all βj = 0
F crit = 5.3177, F = 21.4264
F > F crit, reject H0.
∴There is sufficient evidence to conclude that the type of condition will affect the time
needed for the Browning effect (in minutes) to occur on apple slices.
H0: All αiβj = 0
H1: Not all αiβj = 0
F crit = 4.662, F = 8.1192
F > F crit, reject H0.
∴ There is sufficient evidence to conclude that the interaction effect will affect the time
needed for the Browning effect (in minutes) to occur on apple slices.
∴ In conclusion, all main effects and interaction effects are significant.
3.3 diagnostics of assumptions
In condition A, there is a problem with the distribution with the data being negatively skewed
while in Condition B, the distribution is asymmetric, hence meeting the assumption.
The interpretation is that positive values for the residual (on the y-axis) mean
the prediction was too low, and negative values mean the prediction was too high; 0 means
the guess was exactly correct. Hence, in this plot, the prediction was too high as shown
below.

As evidenced in the interaction plot below where the covariates appearing in the model are
evaluated at the following values: Time needed for the Browning effect (in minutes) to occur
on apple slices = 51.31. Condition B on average takes short time compared to Condition A.
3.4 other relevant statistical tests
Since the interaction is significant, the comparisons between means of one factor may be
obscured by the interaction effect. Therefore, the Tukey’s test and Fisher LSD method is
applied by fixing one factor to the mean of the other factor at the level.
The four solution types average in situation A (covered):
Ӯ11 = (70 + 75)/2 = 72.5 (solution type 1)
Ӯ21 = (100 + 128)/2 = 114.0 (solution type 2)
Ӯ31 = (43 + 41)/2 = 42.0 (solution type 3)
Ӯ41 = (20 + 24)/2 = 22.0 (solution type 4)
Tukey’s test Fisher LSD test

T0.05 = 4.05 (6.9124)
= 28.0
LSD = 2.306 (9.7756)
= 22.54
│Ӯ11 - Ӯ21│: │72.5 -
114│
= 41.5
│Ӯ11 - Ӯ31│: │ 72.5 -
42│
= 30.5
│Ӯ11 - Ӯ41│: │ 72.5 -
22│
= 50.5
│Ӯ21 - Ӯ31│: │ 114 - 42
│
= 72.0
│Ӯ21 - Ӯ41│: │ 114 - 22
│
= 92.0
│Ӯ31 - Ӯ41│: │ 42 - 22
│
= 20.0
> T0.05 = 28.0 > LSD = 22.54
> T0.05 = 28.0 > LSD = 22.54
> T0.05 = 28.0 > LSD = 22.54
> T0.05 = 28.0 > LSD = 22.54
> T0.05 = 28.0 > LSD = 22.54
< T0.05 = 28.0 < LSD = 22.54
These analysis indicates that at the covered situation, the mean of time needed for browning
effect is the same for solution type 3 and 4, while the mean of time needed for browning
effect of comparison between solution type 1 and type 2, 3 and 4 as well as between solution
type 2 and type 3 and 4 are significantly different.
3.5 etc
4.0 Conclusion and Recommendation - 1 ppl (SH)
5.0 References
Amanda, 2013. Why Apples Turn Brown. [online] Available at:
<http://www.decodingdelicious.com/why-apples-turn-brown/> [Accessed 30 March 2020]

Kerri, A. J., 2018. 10 Impressive Health Benefits of Apples. [online] Available at:
<https://www.healthline.com/nutrition/10-health-benefits-of-apples> [Accessed 30 March
2020]