RESUMEN
Texture is an important sensory attribute for overall quality and consumer acceptance of prawns. However, texture is affected during cold storage due to the proteolytic activity of endogenous proteases, resulting in poor quality and a short shelf life. The objective of this study is to determine the inhibitory effects of Annona muricata leaves extract (AMLE) (0, 3, 10 and 20%) on the trypsin, cathepsin B and collagenase activities extracted from the cephalothorax of Macrobrachium rosenbergii. In addition, the textural changes in M. rosenbergii during 20 days of cold storage (4 °C) were also determined. M. rosenbergii were soaked in four different treatments: 0, 3, 10 and 20% AMLE and 1.25% sodium metabisulphate for 10 min at 4 °C. Protease activity was significantly (p < 0.05) reduced at 10 and 20% AMLE. Similarly, cathepsin B showed a significant (p < 0.05) low after treatment at 20% AMLE. The maximum inhibitory activity of trypsin was achieved at 20% AMLE and the standard inhibitor (Tosyl-L-lysyl-chloromethane hydrochloride (TLCK)) compared to the control. Whereas, the lowest collagenase activity was obtained at 20% AMLE compared to the control. These inhibitory effects further maintain the firmness of M. rosenbergii coated with 20% AMLE up to the eighth day of storage when compared to the control. Meanwhile, the highest penetration work was found in the M. rosenbergii coated with 20% AMLE at the twentieth day of storage. In conclusion, treatment at 20% AMLE could be used as a natural preservative to inhibit protease, trypsin and collagenase activity of M. rosenbergii and thus can maintain firmness for up to 8 days of storage.
RESUMEN
Giant freshwater prawn (Macrobrachium rosenbergii) is one of the important aquaculture species and quickly expanding in many countries. High demand and mass commercialization on M. rosenbergii regulating 18% of the international seafood business. Seafood products contend with various level across the supply chains and time to reach the consumers depending upon the marketing and delivery channels after harvesting. Therefore, these may cause biodeterioration such as melanosis (dark pigmentation) and microbial changes that limit the shelf life. This studies reveal the antioxidant properties from Annona muricata leaves extract and their effectiveness in inhibiting the polyphenoloxidase (PPO) activity and delaying the bacterial accumulation during 20 days of chilled storage. Five metabolites including coumarins, flavonoid, glycoside, terpenoids and steroid compound were found in A. muricata leaves extract. Total phenolic content and total flavonoid content of A. muricata were recorded at 191.24 ± 0.03 mgGAEg-1 and 1777.48 ± 1.08 mgQEg-1, respectively. Sixteen percent (16%) of A. muricata leaf extract effectively inhibit 82.41% PPO. Furthermore, 15% of A. muricata leaves extracts showed a significant reduced (p < 0.05) in total bacteria count during 20 days of chilled storage of M. rosenbergii. These conclude that the present of listed secondary metabolites and at approximately ~ 15-16% of A. muricata leaves extracts were effectively inhibiting the melanosis and prolong the shelf life for up to 8 days of M. rosenbergii stored at chilled condition. Therefore, A. muricata leaves extract is potential used as natural preservative agent in obtaining high quality seafood products.
RESUMEN
PRESENTS PROBLEM/FOCUS OF STUDY: The Covid-19 outbreak has had a staggering impact on the global economy, public health and safety, trade and education. In Malaysia, the government implemented the Movement Control Order (MCO) as a preventive measure against Covid-19. In education, the learning process has been transferred to online teaching. However, pandemic pedagogy is making learning into completely online either synchronous or asynchronous. Therefore, the current research aims to determine the secondary school teachers' psychological status, competencies in e-teaching and teachers work motivation as well as determine the relationship between secondary school teachers' psychological status and competencies in e-teaching during the Covid-19 outbreak. DESIGN/METHODOLOGY/APPROACH: Current research is a descriptive-correlational quantitative survey to determine teachers' psychological status, e-teaching competencies and working motivation during Movement Control Order (MCO) to contain the Covid-19 pandemic. The study sample consists of 595 secondary school teachers selected via convenient sampling. Quantitative data are collected from an online survey through the questionnaires with demographic, psychological status (stress, anxiety and depression), e-teaching competencies (teaching, monitoring and evaluation) and teaching motivation developed by the researchers were distributed during the MCO period. SPSS 25 is applied, Statistical measures such as Cronbach's alpha, means, percentage and standard deviation were employed to analyze the data to obtain the value of the school teachers' psychological status, e-teaching competencies and teaching motivation. Consequently, a Pearson correlation table was created to show the analysis of the school teachers' psychological status and competencies in e-teaching. FINDINGS: This finding indicated that the teachers' psychological factors in stress, anxiety and depressed are moderate, the teachers' competencies in e-teaching is moderate as well as teachers' working motivations is also the moderate level. However, the highest mean value was found among the variables, this is revealed that despite the challenges during the Covid-19 outbreak, teachers showed positive and strong motivation in conducting e-teaching. Additionally, the result showed a negative relationship between psychological status and e-teaching competencies (-0.286, p < 0.01), as well as reported a negative relationship between dimension of psychological status and competencies in e-teaching. LIMITATION & RECOMMENDATIONS: This study has its limitations. This study is included only Selangor teachers and given that the information obtained from the study was gather from secondary schools, the generalizability might be limited. future research may consider expanding the scope from secondary schools to primary schools' teachers and then to university lecturers. Perhaps the scope is expanding, so more information could be obtaining and help researchers understand the teachers' competencies in e-teaching, psychological status and work motivation.
