RESULTS GOTTEN FOR PALM KERNEL OIL PROJECT WORK IN ABAKALIKI

CHAPTER FOUR
RESULT ON DISCUSSION
Table 4.1  Effect of Pre-processing Condition on  Saponification Value of Palm Kernel Oil Sample
    
Storage  time                     Saponification Value (meq/kg)
            months                                   Boiled                                    Fermented
0                                  25.25                                      29.45
2                                  42.08                                      57.50
4                                  119.21                                    131.88
6                                  197.75                                    221.59
Total  =12                              384.29                                    440.42

X       =3                                 96.07                                       110.105

R2                                            0.969                                      0.977
2                                             195.74                                    201.39
 



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The result on the effect of pre-processing condition on the characteristics of palm kernel oil revealed that the saponification value of the palm kernel oil sample increased with increase in storage time. Saponification value (SV) obtained for the palm kernel oil samples ranged from 29.45 to 221.59 MgKOH/g and from 25.24 to 197.75 MgKOH/g for palm kernel oil gotten from fermented and boiled palm fruits processing methods respectively, presented in table 4.1. The increase in saponification value with storage time indicated that the amount of soap obtainable from a unit mass of the product palm kernel oil (PKO) increased with time. This suggest that the overall reaction in the stored palm kernel oil resulted in the breakdown of the lipids and fatty acid into smaller molecules leading to lower average molecular weight of the palm kernel oil. (Table 4.1) the sponification value obtained in this study are less than the expected range of 318 to 319MgKOH/g of oil for edible palm kernel oils as specified by NIS (1997), as from 0 month upto 6 months storage. The saponification values of oil for both fermented and boiled process were less than 318MgKOH/g oil, hence not recommended for use in edible purpose within 6 month storage. Low saponification value of the palm kernel oil from both fermented and boiled process is an indication that the oils will be most suitable for biodiesel as an alternative to traditional oil.
            The results were of statistical significant (P<0.05) on the storage time of the palm kernel oil sample, and were not significant (P>0.05) on processing method, while the interaction between storage time and processing method were not significant P>0.05)..

Table 4.2       Effect of the Processing Condition on  Free Fatty Acid of Palm Kernel Oil                                 Sample

            Storagetime                         Free  Fatty  Acid  Value (MgKOH/g)
              months                      Boiled                                    Fermented  
 


                         0                                 6.564                                      1.907 
    
                        2                                  8.308                                      2.917 

                        4                                  9.088                                       3.983

                         6                                 11.108                                     6.900                                                                  Total=12                                35.068                                    15.707                                   
X     = 3                                  8.767                                      3.927                                     
R2                                            0.988                                      0.961
2                                             1.215                                      3.546 
                                               
            The effect of processing condition on the characteristics of free fatty acid (FFA) of palm kernel oil obtained show different methods is presented in (Table 4.2). The result indicate that there was a remarkable increase in FFA of palm kernel oil from the boiled processing method of palm fruits than the one from fermentation processing method throughout the storage period. From the result obtained in table 4.2, it can be seen that the acid value increased from 6.564 MgKOH/g to 11.108MgKOH/g within the palm kernel oil storage time of 6 months. The increment in the value with storage time could be due to hydrolysis or splitting of some fats and oil (lipids) to give more fats acids, diglycerides and monoglycerides. The value obtained were not within the range reported by AOCS, (1996) and Swerm et al, (1964). Storage time and processing method are significant effect (P>0.05) on the FFA while  the interaction between  the storage time and processing method are not significant (P>0.05) on free fatty  acid of the palm kernel oil sample.

Table 4.3 Effect of Pre-processing Condition on  Peroxide Value of Palm Kernel oil Sample

Toragetime                          Peroxide Value  (Meq/Kg)
 months                                  Boiled                        Fermented
                        0                                  28.60                          26.60
                        2                                  39.00                          32.60
                        4                                  41.60                          38.20
                        6                                  46.40                          45.60
            Total=12                                155.6                          143
X      =3                                  38.9                            35.75
            R2                                            0.965                          0.998
2                                             4.361                          5.501

            The peroxide value determine the extent to which the oil has under gone rancidity, thus it could be used as an indication of the quality and stability of fats and oils (Ekwu and Nwagu, 2004) the peroxide value (Meq/Kg) of the palm kernel oil extracted from fermented and boiled palm fruits increased with increase in storage time respectively (Table 4.3), with the palm kernel oil from boiled palm fruits process had the higher peroxide values from 28.60 Meq/Kg to 46.40 M­eg/Kg during the 6 month of storage period, than palm kernel oil from fermentation process ranging from 26.60 Meq/Kg to 45.60 Meq/Kg during the 6 months storage period. The statistical analysis shows that there is significant variation on the storage time, no significance difference (P>0.05) on processing method. while the interaction between the storage time and processing method are not significant (P>0.05) on the peroxide value of palm kernel oil sample. Steady increase in the peroxide value of palm kernel oil with storage time could be due to increase in the extent of oxidation resulting in increase in the formation of hydro peroxides during fats oxidation. The observation that the peroxide values of palm kernel oil from boiled palm fruits process were higher than those from fermented process could be due to the fact that initial extent of hydrolysis was higher in the product of the boiled process. Although peroxides are possibly not directly responsible for the taste and odour of rancid fats, their concentration is often useful  in accessing the extent to which the rancidity has advanced.
            As presented in (Table 4.3) the peroxide value range from 28.60 to 46.40 Meq/Kg and 26.60 to 45.60 Meq/Kg for boiled and fermented process are highly than the standard minimum value of 10 Meq/Kg specified by SON (2000) and NIS (1992). Within the 6 months storage period, the peroxide value of palm kernel  oil gotten from both fermented and boiled process were great than 10 Meq/Kg oil, hence not recommended for  used in edible purpose within the 6 months storage time without refining. The increase in peroxide value with increase in storage time could indicate the onset of primary oxidation due to lipid degrading enzymes like peroxidase and lipoxygenase  Onyeka et al (2005) which progressed with time.                

      Table 4.4   Effect of Pre-processing Condition on Iodine Value of Palm Kernel Oil                                     Sample
            Storagetime                                     Iodine  Value  (Wij/s)
                Mouths                                          Boiled         Fermented
                        0                                              5.329                          0.508
                        2                                              6.599                          0.761
                        4                                              8.122                          1.269
                        6                                              10.659                        2.30
            Total=12                                            30.569                        4.568
            X     =3                                               7.677                          1.142
            R2                                                        0.986                          0.976
2                                                         2.054                          1.184
 


            Iodine value is an index of the degree of unsaturation, which is one of the most important analytical characteristics of oil. The on changes in the iodine value of the palm kernel oil is presented in (Table 4.4) it was observed from the figure that iodine value increased during storage time of the palm kernel oil from the two processes studied.  Minimum iodine value was 5.329 Wij’s initially in palm kernel oil from boiled palm fruits process and 0.508 Wij’s in palm kernel oil from fermented palm fruits process. The values increased to 10.659 and 2.030 Wij’s for palm kernel oil from boiled and fermented palm fruits respectively at the end of 6 months storage period (Table 4.4). The changes in iodine value of palm kernel oil samples may be attributed to propagation of auto oxidation process where hydro peroxides are formed from free radicals in fatty acids generated by initiation stage of the auto oxidation reaction. The iodine value obtained were within the limits of standard range of 45 to 53 Wij’s, recommended by SON (2000) NIS (1992). However, the value obtained indicate the increase in iodine value with storage time of palm kernel oil could be due to the detachment of fatty acids which can lead to increase in degree of unsaturation of the lipid (oil) and therefore, susceptible to oxidation.
            The addition of antioxidants may be necessary to prolong the storage stability of this type of palm kernel oil. The storage time, processing method and the interaction between the storage time and processing method on the iodine value of the palm kernel oil sample had significant effect (P>0.05) on the iodine value.

Table 4.5       Effect of Pre-processing Condition on Moisture Content of Palm kernel Oil Sample
    
Storagetime                           Moisture Content  (%)    
 Months                                 Boiled            Fermented
                        0                                  9                                  6
                        2                                  12.5                            11
                        4                                  15.5                            14
                        6                                  18                                16.5
            Total=12                                55                                47.5
            X     =3                                   13.75                          11.88
            R2                                            0.997                          0.986
2                                             3.291                          5.150
 


            Moisture content is the quantity of water contained in a material such as oil, it is used in a likely range of scientific and technical areas and its expressed as ratio can range from 0 (completely dry) to the value of the materials porosity at saturation. The moisture content is one of the most important indicator of oil determination. The changes in moisture content during 6 months of storage period are given in (Table 4.5). The moisture increase from 0 month of storage period 9% to 18% for the palm kernel oil from boiled palm fruits and 6% to 16.5% for the palm kernel oil from fermented palm fruits. The increases of moisture content of the palm kernel oil both the one extracted from boiled and fermented palm fruits during the storage period could be due to the storage environment of the palm kernel oil. The value obtained are higher than value (6.5%) reported by Alasie et al (2009). The result in the moisture content shows that the storage time of the palm kernel oil sample are significant effect (P<0.05) on the moisture content while the processing method were not significant (P>0.05) and the interaction between storage time and processing method were not significant on moisture content.


Table 4.6       Effect of Pre-processing Condition on Melting Point of Palm kernel Oil                         Sample

             Storagetime                                     Melting  Point (oC)
                Months                              Boiled                        Fermented
                        0                                  26                                            27
                        2                                  24                                            26
                        4                                  23                                            25
                        6                                  21                                            24
            Total=12                                94                                            102
            X      =3                                  23.5                                        25.5
            R2                                            0.992                                      1
2                                             0.553                                      0.196
 


            The experimental results showed decrease in the melting point of palm kernel oil from both the one extracted from boiled and fermented palm fruits. The decrease in melting point of palm kernel oil from boiling process was only from 26oC to 21oC for the 6 months storage period while for fermentation process decreased from 270C to 24oC (Table 4.6). The high melting point observed for palm kernel oil from fermentation process of palm fruits could be due to the presences of some high melting saturated components in the palm kernel oil sample. By boiling the palm fruits, the portion of the unsaturated fatty acids increased but these fatty acids do not take part in any chemical change in the oil, do not  interact with triacylglycerol as they are of similar chemical composition of the molecular species of triacylglycerol would have changed the other physical properties of the palm kernel oil as the physical and chemical properties of palm kernel oils are function of fatty acids in triglycerides (Tan and Man 2002; Fogila et al, 1993).
            The melting behavior of the palm kernel oil from both boiled and fermented varies due to the different characteristics and composition of fatty acids in terms of triglycerides in both processed palm fruits (Fassina et al, 2008). The melting point  were of statistical significant (P<0.05) on the storage time, processing method and interaction between storage time and processing method on the melting point of the palm kernel oil sample.

    Table 4.7   Effect of Pre-processing Condition on Freezing Point of Palm kernel Oil                                    Sample
    
            Storagetime                                     Freezing  Point  (oC)
 Months                                             Boiled            Fermented
                        0                                              0                                  0
                        2                                              2.0                               2.2
                        4                                              2.1                               2.3
                        6                                              2.4                               2.5
Total   12                                            6.5                               7
            X         3                                              1.63                            1.75
            R2                                                        0.946                          0.935
2                                                         2.213                          2.361
 


The result presented in (Table 4.7 ), shows that the freezing point slightly increased with storage time for both procedures. These show that the component with the lowest freezing point did not significantly change with storage time. However, the products from fermentation process had higher freezing point from (0oC to 2.5oC) than those from boiled process of palm fruits (0­0C to 2.40C). This could be due to the fact that fermented process had the capability of extracting higher broad spectrum of component which resulted during n-hexane extraction of palm kernel oil including the poly unsaturated which had lower freezing points. The result were statistical not significant (P>0.05) for both storage time, processing method and interaction between the storage time and processing method on the freezing point of palm kernel oil sample

Effect of Pre-processing Condition on  the stability of Palm kernel Oil Sample
            The stability of palm kernel oil (PKO) were measured by the rate change of key properties such as the free fatty acid and peroxide value as presented in (table AI), it should be noted that process of oxidation and hydrolysis normally go through induction, propagation and termination steps and antioxidants can help in early onset of termination. The sample from fermentation process of palm kernel oil gotten from palm fruit displayed higher hydrolytic stability having lower rate of change of free fatty acid with storage time. (   FFA/  t) this could be due to the fact that the product from palm kernel oil gotten from boiling process of palm fruits experience hydrolysis during the boiling period and this hydrolysis had already gotten through the initiation and propagation stages prior to the oil production where as the fermentation process experience less hydrolysis which may still be in the induction prior to oil production. From the result it can also be seen that for both processes, the stability decreased with storage time up to 4 months after which it increased. The decrease in stability up to 4 months was as a result of the propagation step of free fatty acid liberation been higher than the termination may have become predominant leading to the reduction in FFA liberation and observed increase in hydrolytic stability. The oxidative stability of palm kernel oil extracted from boiling process of palm fruits were higher than those of palm kernel oil extracted from fermentation process of palm fruits as shown in Appendix A1. The reason for this is probably due to the fact that the fermentation operation retard some hit labile antioxidants which could have aided in the oxidation reaction where as the boiling process did not.

            On the effect of pre-processing condition, the oxidation stability decreased with storage time up to 6 months after which it increased with time. This is similar to the observation on the variation of hydrolytic stability with storage time. Similar reason can be deduced. In order words, the propagation step control the oxidation reaction up to 6 months while the termination step took over after 6 months. Furthermore, the reaction of the peroxides to other products such as aldehydes and ketones may have set in after 6 months storage result in decrease in observed rate of increase in peroxide value.


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