PERTANIKA JOURNAL OF SCIENCE AND TECHNOLOGY

This study optimized microbial growth inhibition conditions using pineapple leaf juice (PLJ). The sugarcane press machine was used to press the PLJ. The study considered four factors to be analyzed by Two-level factorial design (TLFD), which are microbial inhibition time (0.5–5 h), the concentration of total phenolic content (TPC) (0.2563–0.5127 mg GAE/ mL), temperature (26–37 °C), and the ratio of PLJ to microbe (PLJ/M) (v/v) (1:1 and 1:3). Colony-forming unit (CFU) method was employed to measure microbial growth inhibition. The microbial growth inhibition was expressed as a percent in terms of CFU/mL. A central composite design (CCD) experimental design created using response surface methodology (RSM) determined the optimum temperature (35–39 °C) and microbial inhibition time (10–50 min) of microbial growth inhibition. The best conditions were 0.5 h of microbial inhibition time, 0.5127 mg GAE/mL of TPC, 1:1 PLJ/M, and a temperature of 37 °C. The analysis of variance (ANOVA) showed that temperature (Factor C) has the greatest contribution (1.56%) to inhibiting microbial growth, accompanied by TPC concentration in PLJ (Factor B) with 1.27%, microbial inhibition time (Factor A) with 1.07% and PLJ/M (Factor D) 0.29%. Optimization studies show that at an optimum temperature of 37 °C and an inhibition time of 34.25 min, maximum microbial growth inhibition of 94.73% with a minimum value of 9.12×104 CFU/mL was achieved. This research suggests that PLJ can be utilized as a value-added natural product for application in the agricultural sector.

• Ammer, M. R., Zaman, S., Khalid, M., Bilal, M., Erum, S., Huang, D., & Che, S. (2016). Optimization of antibacterial activity of Eucalyptus tereticornis leaf extracts against Escherichia coli through response surface methodology. Journal of Radiation Research and Applied Sciences, 9(4), 376-385. https://doi.org/10.1016/j.jrras.2016.05.001

• Arshad, M. S., & Batool, S. A. (2017). Natural antimicrobials, their sources and food safety. In D. N. Karunaratne & G. Pamunuwa (Eds.), Food Additives (pp. 87-104). InTech. https://doi.org/10.5772/intechopen.70197

• Asim, M., Abdan, K., Jawaid, M., Nasir, M., Dashtizadeh, Z., Ishak, M. R., & Hoque, M. E. (2015). A review on pineapple leaves fibre and its composites. International Journal of Polymer Science, 2015, Article 950567. https://doi.org/10.1155/2015/950567

• Aydar, A. Y. (2018). Utilization of response surface methodology in optimization of extraction of plant materials. In V. Silva (Ed.), Statistical Approaches with Emphasis on Design of Experiments Applied to Chemical Processes (pp. 157-169). IntechOpen. https://doi.org/10.5772/intechopen.73690

• Domínguez, C. R., Avila, J. A. D., Pareek, S., Ochoa, M. A. V., Zavala, J. F. A., Yahia, E., & González-Aguilar, G. A. (2018). Content of bioactive compounds and their contribution to antioxidant capacity during ripening of pineapple (Ananas comosus L.) cv. Esmeralda. Journal of Applied Botany and Food Quality, 91, 61-68. https://doi.org/10.5073/JABFQ.2018.091.009

• Eddleman, H. (1998). Optimum temperature for growth of bacteria. Indiana Biolab Palmyra IN.

• Hajdu, S., Holinka, J., Reichmann, S., Hirschl, A. M., Graninger, W., & Presterl, E. (2010). Increased temperature enhances the antimicrobial effects of daptomycin, vancomycin, tigecycline, fosfomycin, and cefamandole on staphylococcal biofilms. Antimicrobial Agents and Chemotherapy, 54(10), 4078-4084. https://doi.org/10.1128/AAC.00275-10

• Hoskeri, J., Krishna, H., Jignesh, V., Roshan, S., & Vijay, S. (2012). In-silico drug designing using β-sitosterol isolated from Flaveria trinervia against peptide deformylase protein to hypothesize bactericidal effect. International Journal of Pharmacy and Pharmaceutical Sciences, 4, 192-196.

• Jayaratne, D. L., & Dayarathna, M. T. A. (2015). Phenotypic variability of ceratocystis paradoxa isolated from North Western and Western Provinces of Sri Lanka and its bio control by potential bio-control agent; Trichoderma viride. Coconut Research & Development Journal, 31(2), 10-10. https://doi.org/10.37833/cord.v31i2.61

• Klimczak, I., Małecka, M., Szlachta, M., & Gliszczyńska-Świgło, A. (2007). Effect of storage on the content of polyphenols, vitamin C and the antioxidant activity of orange juices. Journal of Food Composition and Analysis, 20(3-4), 313-322.

• Lee, D. S., & Lemieux, T. (2010). Regression discontinuity designs in economics. Journal of Economic Literature, 48(2), 281-355. https://doi.org/10.1257/jel.48.2.281

• Lobo, V., Patil, A., Phatak, A., & Chandra, N. (2010). Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy Reviews, 4(8), 118-126. https://doi.org/10.4103/0973-7847.70902

• López‐García, B., Hernández, M., & Segundo, B. S. (2012). Bromelain, a cysteine protease from pineapple (Ananas comosus) stem, is an inhibitor of fungal plant pathogens. Letters in Applied Microbiology, 55(1), 62-67. https://doi.org/10.1111/j.1472-765X.2012.03258.x

• Maqsood, S., Benjakul, S., Abushelaibi, A., & Alam, A. (2014). Phenolic compounds and plant phenolic extracts as natural antioxidants in prevention of lipid oxidation in seafood: A detailed review. Comprehensive Reviews in Food Science and Food Safety, 13(6), 1125-1140. https://doi.org/10.1111/1541-4337.12106

• Noormohamadi, H. R., Fat’hi, M. R., Ghaedi, M., Azizzadeh, S., & Nobakht, V. (2018). Mechanochemically synthesized Ag (I) coordination polymer as a new adsorbent and its application to ultrasound assisted wastewater treatment via the central composite design: Isotherm and kinetic studies. Journal of Molecular Liquids, 262, 71-77. https://doi.org/10.1016/j.molliq.2018.04.042

• O’Toole, G. A. (2016). Classic spotlight: Plate counting you can count on. Journal Bacteriol, 198(23), 3127-3127. https://doi.org/10.1128/JB.00711-16.

• Reichhardt, C., Lim, J. Y., Rice, D., Fong, J. N., & Cegelski, L. (2014). Structure and function of bacterial biofilms by solid-state NMR. Biophysical Journal, 106(2), Article 192a.

• Saunders, L. J., Russell, R. A., & Crabb, D. P. (2012). The coefficient of determination: What determines a useful R2 statistic? Investigative Ophthalmology & Visual Science, 53(11), 6830-6832. https://doi.org/10.1167/iovs.12-10598

• Shane, H. (2017). What is the Purpose of Factor Analysis? Sciencing. https://sciencing.com/what-is-the-purpose-of-factor-analysis-12225143.html

• Siddiqui, N., Rauf, A., Latif, A., & Mahmood, Z. (2017). Spectrophotometric determination of the total phenolic content, spectral and fluorescence study of the herbal Unani drug Gul-e-Zoofa (Nepeta bracteata Benth). Journal of Taibah University Medical Sciences, 12(4), 360-363. https://doi.org/10.1016/j.jtumed.2016.11.006

• Ya’acob, A., Zainol, N., Ridza, P. N. Y. M., Mortan, S. H., & Samad, K. A. (2021). Pineapple leaf juice characterization and evaluation of factors affecting microbial growth inhibition. Biocatalysis and Agricultural Biotechnology, 37, Article 102158. https://doi.org/10.1016/j.bcab.2021.102158

• Zafrilla, P., Morillas, J., Mulero, J., Cayuela, J. M., Martínez-Cachá, A., Pardo, F., & López Nicolás, J. M. (2003). Changes during storage in conventional and ecological wine: Phenolic content and antioxidant activity. Journal of Agricultural and Food Chemistry, 51(16), 4694-4700.

• Zainol, N., & Rahim, S. R. (2017). Factorial analysis on Bacillus Sp. removal using garlic solution. Journal of Chemical Engineering and Industrial Biotechnology, 1(1), 18-28. https://doi.org/10.1088/1757-899X/342/1/012037

• Zhang, Q. Y., Zhou, W. W., Zhou, Y., Wang, X. F., & Xu, J. F. (2012). Response surface methodology to design a selective co-enrichment broth of Escherichia coli, Salmonella spp. and Staphylococcus aureus for simultaneous detection by multiplex PCR. Microbiological Research, 167(7), 405-412. https://doi.org/10.1016/j.micres.2012.02.003

• Zhang, Y., Truzzi, F., D’Amen, E., & Dinelli, G. (2021). Effect of storage conditions and time on the polyphenol content of wheat flours. Processes, 9(2), Article 248. https://doi.org/10.3390/pr9020248