Quality and biochemical changes of longan (Dimocarpus longan Lour cv. Daw) fruit under different controlled atmosphere conditions

Abstract

Sulphur dioxide has been used to control pericarp browning in longan fruit. However, due to health and regulatory concerns, alternative treatments should be tested. The objective of this study was to find the tolerance levels of longan fruit to low O2 (2%, 5%, 10% and 15%) and elevated CO2 (5%, 10%, 15% and 20%) at 2 °C. According to the tolerance study, controlled atmospheres (CA) of 5% O2 + 5% CO2, 5% O2 + 10% CO2 and 5% O2 + 15% CO2 were compared with normal air (control) at 2 °C. Pericarp browning and decay incidence of longan were significantly (P ≤ 0.05) higher in control than all the CA treatments. CA storage reduced polyphenol oxidase (PPO) activity, maintained L* value and slowed down a decrease in total phenolic contents (TPC). Pericarp browning was highly correlated with PPO, L* and TPC.

Effects of Various Polymeric Films on the Pericarp Microstructure and Storability of Longan (cv. Shixia) Fruit Treated with Propyl Disulfide Essential Oil from the Neem (Azadirachta indica) Plant

“…The pericarp browning index (BI) of longan fruit was determined by observing the amount of total brown area on each fruit surface, whereby 1 = 0% (no browning), 2 = 1–10% (slight browning), 3 => 10–25% (moderate browning), 4 => 25–50% (severe browning), 5 => 50%, calculated using the below equation [ 20 ]. Fruit with a browning scale above 3 was the limit of acceptability: …”

“…Phenolic and flavonoid contents were extracted from the pericarps of 15 fruit samples according to Khan et al [ 20 ]. Reaction mixtures for TPC and TFC were prepared according to the methods of Khan et al [ 20 ] and Dewanto et al [ 21 ], respectively, using a UV–visible spectrophotometer (SPECORD 50 Plus, Analytik Jena, Germany). The results for TPC and TFC were expressed as milligrams of gallic acid per kg and milligrams of catechin per kg of fresh weight, respectively.…”

Modified Atmosphere Packaging Reduces Pericarp Browning and Maintains the Quality of ‘Huong Chi’ Longan Fruit (Dimocarpus Longan) Pretreated with Citric Acid

“…However, SO2 fumigation can leave undesirable residues which result in a negative effect on the sensory quality of the fruit and pose health risks to consumers (Sivakumar & Korsten, 2006). The application of SO2 fumigation has been restricted or prohibited in many countries (Khan et al, 2017). Previous studies have been carried out to investigate alternatives such as chitosan coating (Jiang & Li, 2001;Apai et al, 2009), hydrochloric acid (Apai, 2010), hydroxyl radical application (Duan et al, 2011), chlorine dioxide fumigation (Saengnil et al, 2014;Chumyam et al, 2017), and adenosine triphosphate treatment (Chen et al, 2015) to prolong the shelf life and prevent pericarp browning for longan fruit.…”