There have been increased efforts to identify new edible coating and preservative compounds derived from natural sources. This study aimed to investigate the effect of two different concentrations (1.0 % and 1.5 %) of Malaysian stingless bee honey (SBH) as an edible coating agent on the quality attributes of papayas (Carica papaya L.) during storage. Quality parameters such as fresh weight loss (FWL), firmness, soluble solids content (SSC), titratable acidity (TA), colour, and respiration rate were investigated during 12 d of storage at 12 ± 1 °C. The results indicated that papayas coated with 1.0 % and 1.5 % of SBH significantly retained their firmness, colour, SSC, and TA, in addition to the reduced FWL and respiration rate as well as delayed decay development in fruits compared to the uncoated samples. The results of the Field Emission Electron Microscopy revealed that the SBH coating also prevented the ultrastructural features of the mitochondria. In addition, the zero-order and first-order kinetic models fitted well with the experimental data for both coated and uncoated papayas using the Arrhenius law approach. These results suggest that the SBH-coated layer not only improved the postharvest quality of papayas during storage but also prolonged their storage life.

Pineapple waste accounts for a significant part of waste accumulated in landfill which will further contribute to the release of greenhouse gases. With the rising pineapple demands worldwide, the abundance of pineapple waste and its disposal techniques are a major concern. Exploiting the pineapple waste into valuable products could be the most sustainable way of managing these residues due to their useful properties and compositions. In this review, we concentrated on producing useful products from on-farm pineapple waste and processing waste. Bioenergy is the most suitable option for green energy to encounter the increasing demand for renewable energy and promotes sustainable development for agricultural waste. The presence of protease enzyme in pineapple waste makes it a suitable raw material for bromelain production. The high cellulose content present in pineapple waste has a potential for the production of cellulose nanocrystals, biodegradable packaging and bio-adsorbent, and can potentially be applied in the polymer, food and textile industries. Other than that, it is also a suitable substrate for the production of wine, vinegar and organic acid due to its high sugar content, especially from the peel wastes. The potentials of bioenergy production through biofuels (bioethanol, biobutanol and biodiesel) and biogas (biomethane and biohydrogen) were also assessed. The commercial use of pineapples is also highlighted. Despite the opportunities, future perspectives and challenges concerning pineapple waste utilisation to value-added goods were also addressed. Pineapple waste conversions have shown to reduce waste generation, and the products derived from the conversion would support the waste-to-wealth concept.

The outbreak of a neurological disorder was first discovered as a new coronavirus (2019-nCoV) in Wuhan, China. The infection spread rapidly in China and throughout the world, including Malaysia. Malaysia recorded its initial case on 25 January 2020 with intensifying numbers since March 2020. Due to this uncertain circumstance, Malaysia has introduced the Movement Control Order (MCO) with the main aim of isolating the source of the COVID-19 outbreak, which was effective from 18 March 2020. The restriction has observed fewer vehicles on the road with industrial and commercial activities being suspended. The objective of the study is to quantify the effects of MCO to food waste generation in town and district areas of Klang Valley, Malaysia. Food waste generation data was derived from the Project Delivery Department, KDEB Waste Management on a daily basis before (19 February–17 March 2020) and during the MCO (18 March–14 April 2020) at 12 local authorities in Selangor, Malaysia. The data was obtained with the limitation of assumption that there is no waste compositional analysis to be conducted in 2020. Despite the stay-at-home order, food waste data showed a descriptive reduction of up to 15.1% during the MCO. Statistical analysis of food waste generation from one-way variance has shown that municipal and district local authorities recorded a significant reduction (p < 0.50) during the MCO. The food waste reduction during the MCO will deliver as the evidence-based results to push the need for policies in Malaysia as per the goals outlined in Sustainable Development Goals of global food loss and waste.

A proposed method for citronella oil extraction was developed with the application of ohmic heated hydro-distillation. The objective was to compare the performance of three different extraction methods, viz. ohmic heated hydro-distillation, hydro-distillation, and steam distillation. The maximum amount of extracted oil yield by ohmic heated hydrodistillation was 7.64 mL/kWh as compared to hydro-distillation and steam distillation methods that resulted oil yields of 3.87 mL/kWh and 1.69 mL/kWh, respectively. The kinetics of extraction followed a second-order model. Gas chromatography-mass spectrometry analysis found that the major constituents of citronella oil (GC-MS) for the different extraction methods were citronellal, citronellol, and geraniol. Scanning electron microscopy (SEM) of citronella grass provided evidence that the lignocellulosic sources of the extracted citronella oil were schizogenous cavities and cellular lignin. The citronella that had undergone ohmicheated hydro-distillation and steam distillation showed some microfractures and less cell wall degradation than hydro-distillation. The cell walls were less rigid using ohmic-heated hydro-distillation compared to steam distillation. However, the cell walls of the hydro-distillation sample were less dense and exhibited pronounced swelling, but did not show any microfractures.

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This work assesses the behavior of organosolv lignin aggregates derived from Miscanthus x giganteus using different ethanol concentrations (10%, 25%, 50%, and 75% by volume). The percentage of lignin recovery was found to decrease from 75.8% to 71.4% and 25.1%, as the ethanol concentration was increased from 10% to 25% and 50%, respectively. Increasing the ethanol concentration further to 75% led to zero recovery. The purity of the precipitated lignin was consistently found to be ≥90%. Lignin derived from the dried supernatant obtained at 50% ethanol concentration resulted in high lignin purity (51.6%) in comparison with the other ethanol concentrations used. Fourier transform infrared spectroscopy analysis showed that the precipitated lignin and dried supernatant at 50% ethanol concentration possessed the highest peak intensity apportioned to wavenumber of lignin as compared to that of at 25% and 10% ethanol concentrations, and the results linked with the percentage of lignin purity. The results of particle size analysis for precipitated lignin demonstrated particle sizes of 306, 392, and 2050 nm for 10%, 25%, and 50% ethanol concentrations, respectively, and the remaining supernatant with average particle sizes of 1598, 1197, and 875 nm, respectively. These results were verified with the morphology of lignin macromolecules in scanning electron microscopy images. Results of the particle size distribution of lignin revealed that the overall size of lignin aggregates decreased with decreasing ethanol concentration. In summary, these findings suggest that ethanol concentration affected the behavior of lignin aggregates in water–ethanol solution.

The abundance of agricultural wastes produced from pineapple processing and livestock industries has resulted in the difficulties of disposing of a large amount of waste. Anaerobic digestion is a way to reduce waste and generate renewable energy sources including biogas. In this study, pineapple waste is co-digested with cow dung in batch experiments under mesophilic temperature at 38±1°C at a working volume of 100 ml in 125 ml serum bottle. The effects of the total solid on methane yields are investigated at a different substrate ratio. The batch study is conducted at 3 different total solid which are 12%, 20% and 28% and at three different substrate ratio cow dung to pineapple waste (CD: PW) (1:1, 1:2 and 1:3). Daily biogas collection for 28% total solid at 1:1 ratio results in the highest cumulative biogas production of 313 ml, followed by 28% total solid at 1:3 ratio with 246 ml biogas yield. The highest methane yield is achieved at 12% total solid with a 1:2 ratio (17.19 CH4/g VS). Results show that at 12% total solid produces the highest methane yield at all ratios compared to other total solid percentages. Moreover, methane yield decreases as the total solid percentage increases from 12% to 28%. Overall, the production of methane from pineapple wastes co-digested with cow dung is proven to be a good strategy to minimise solid wastes.