## 3 Results and Discussion
### Colour Properties  
During the storage days, the colour values of ground beef samples were influenced by the inclusion of MOLP in all treatments, as presented in Table 4. The lightness values of treated ground beef samples increased from days 0 to 15 with an increase of MOLP concentration. For the control sample, lightness values decreased with the passage of time. The low L * value in the control sample might be attributed to the high levels of redness in meat and muscle pigment. [PERSON] et al. [45] reported a reduction in the L * value of chicken patties with the inclusion of pomergranate peel powder extract. In addition, [PERSON] and [PERSON] [64] observed an increase in the L * value of frozen vacuum-packaged pork and beef during the frozen storage period of 4 months, although it later stayed constant due to the inclusion of natural antioxidants. Moreover, the inclusion of MO seed flour increased the L * values of beef patties [65]. The a * (stability of the red colour) values significantly increased (\(p<0.05\)) with the increase of MOLP concentration in treated ground beef samples. The control sample had lower a * values throughout the storage period. Low a * values of control sample during storage is related to oxidised myoglobin, metmyoglobin formation, and lipid oxidation of meat products [53]. [PERSON] et al. [63] reported the probability of oxidation of pigment that catalyses lipid oxidation and produces free radicals that might oxidise the iron atom as well as denature the myoglobin molecules, causing a decrease in meat colour. Nevertheless, different factors can influence the stability of meat colour but the formation of metmyoglobin due to free radicals is the main cause of this phenomenon [66]. These results are similar to those of [PERSON] et al. [67] and [PERSON] et al. [50], wherein the inclusion of plant extracts improved the a * values of beef patties. There was reduction of b * (yellowness) in the control sample in comparison with samples treated with MOLP during storage. The yellowness increased with an increase in concentration of MOLP but decreased with storage. The increase in yellowness of treated ground beef might have been due to the presence of carotenoids in MOLP [68]. However, these results are different from those of [PERSON] et al. [53] and [PERSON] et al. (2014), who reported that the inclusion of MOLP decreased b * values of beef patties and raw pork during storage. The chroma significantly increased with the addition of MOLP in comparison with the control sample, but decreased with storage. The increase in chroma values of treated ground beef might have been due to an increase in a * values with the addition of MOLP [69]. Therefore, the addition of MOLP improved colour intensity of ground beef. [PERSON] et al. [40] reported similar results, wherein the addition of MO leaf meal increased the chroma values of chicken breast meat. The H * (hue angle) value of the control sample was significantly (\(p<0.05\)) higher than ground beef treated with MOLP. This implies that a high concentration of MOLP decreased the hue angle of raw ground beef. Therefore, MOLP shifted the hue angle to below the average in the control sample. These findings show a similar trend to that reported by [PERSON] et al. [70], wherein the inclusion MO meal decreased the H * value of the Mexican hairless pig meat. Low a * and C * values and high H * values indicate meat discolouration due to their positive association with concentration of metmyoglobin in meat and meat products [71]. The total colour difference (\(\Delta\)E) of the control sample was significantly higher (\(p<0.05\)) than ground beef samples treated with MOLP. However, there was no significant difference (\(p>0.05\)) between treated ground beef samples during storage. The total colour difference is noticeable when it is beyond 2 [72]. On the basis of this information, the control sample had a measurable colour difference from 5, 10, and 15 days of storage, and the treated sample (0.8%) showed a noticeable difference at day 10.