Physicochemical Properties of Whole and Fresh Cut Durian (Durio Zibethinus) Stored At Ambient and Refrigerated Temperatures

This study reports chemical changes occurring in the pulp of both whole and minimally processed (MP) durian (Durio zibethinus) stored at ambient and refrigerated temperatures. In the first part of this study, the pH, total soluble solids, titratable acidity, sugars, organic acids, flavour compounds and sensory properties of five Malaysian durian cultivars (‘D2’, ‘D24’, ‘MDUR78’, ‘D101’ and ‘Chuk’) were determined. There were significant differences in physicochemical characteristics among the cultivars. Analysis using solid-phase microextraction (SPME) coupled to gas chromatography- time of flight mass spectrometry (GC-TOFMS) revealed a total of 22 esters, 14 sulphur compounds, 7 alcohols, 3 aldehydes and 1 ketone in the pulp of the 5 durian cultivars. Sensory properties of four durian cultivars were compared. Twelve descriptors (sweet, fruity, sulphury, alcohol, nutty and green aroma, surface color, sweetness, bitterness, stickiness, moistness and overall aftertaste) were generated. A strong correlation was observed between sensory properties, flavour compounds and physicochemical characteristics of the fruit. In the second part of this study, activities of four cell wall hydrolases, pectinmethylesterase (PME), polygalacturonase (PG), cellulase and β-galactosidase (β-Gal) and physicochemical changes of ripen whole durian fruit (cultivar D24 and an accession from Kampung Bentong, Pahang) stored at 28 + 1 °C (RH 60-80%) for 4 days, were investigated. During storage, significant interaction effect of ‘accession x day of storage’ on weight loss, glucose content, PG and PME enzymes activities were observed. Weight loss increased linearly with an average weight loss of 3.9 and 4.9% per day for durian kampung and D24 respectively. The softer texture observed in the Kampung Bentong accession as compared to the D24, corresponded to its higher PG and cellulase activity. Transmission electron microscopy observations showed middle lamella dissolution and loss of intercellular materials in Kampung Bentong accession after 4 days of storage but not in the D24. The effect of storage temperature on the changes in the physicochemical, microbial and sensory quality of MP durian cultivar D24 was then determined at 28+1 oC for 3 days and 4+2 oC for 35 days. Around 400 g pulp was placed on a polystyrene tray and wrapped with LDPE film for storage. At 28+1 oC, the pulp retained its colour but softened rapidly after 24 h of storage and became acidic (pH 4.71) after 2 days of storage due to the formation of citric, succinic, acetic and lactic acids. Titratable acidity of the pulp that increased significantly after 2 days of storage was correlated to the decrease in pH. Sucrose decreased concomitantly with an increase in glucose and fructose concentrations during storage. For pulp stored at 4+2 oC, no noticeable changes in pH were observed. After 1 week of storage, there was a progressive increase in glucose, fructose and sucrose concentration with concomitant increase in total soluble solids. The firmness increased significantly at the end of storage. The organic acid content remained constant throughout the storage period with a slight increase in tartaric acid. Titratable acidity of the pulp decreased significantly after one-week storage and remained constant thereafter. The MP durian fruit could be kept at 4+2 oC for 14 days with acceptable microbiological quality and without development of off-odour. At ambient temperature, MP durian could only be stored for 1 day, after which the pulp became acidic. The volatile flavour compounds and sensory attributes of MP durian cultivar D24 stored at 4+2 ºC for 42 days were examined. The volatile compounds were extracted by SPME and analysed by GC-TOFMS. During storage of MP durian at 4+2 ºC, diminution of the major ester compounds was observed after 14 days of storage. All ester compounds decreased significantly after 7 days of storage except for ethyl acetate that decreased significantly after 2 weeks of storage. Ethanethiol, 1-propanethiol, and both isomers of 3,5-dimethyl 1,2,4-trithiolane decreased significantly after 7 days of storage. Total sulfur content of the pulp remained unchanged after 42 days of storage. However, sulfur notes perceived by panellists decreased gradually throughout storage. Quantitative Descriptive Analysis (QDA) was carried out using sixteen descriptors to describe the surface colour, odour, flavour and texture of pulp during storage. Results revealed that pulp could be stored for 21 days, after which off flavour developed and the green aroma became too intense and rendered the pulp unacceptable

Word Mode: a crowding-free reading protocol for individuals with macular disease

Central retinal loss through macular disease markedly reduces the ability to read largely because identification of a word using peripheral vision is negatively influenced by nearby text, a phenomenon termed visual crowding. Here, we present a novel peripheral reading protocol, termed Word Mode, that eliminates crowding by presenting each word in isolation but in a position that mimics its natural position in the line of text being read, with each new word elicited using a self-paced button press. We used a gaze-contingent paradigm to simulate a central scotoma in four normally-sighted observers, and measured oral reading speed for text positioned 7.5° in the inferior field. Compared with reading whole sentences, our crowding-free protocol increased peripheral reading speeds by up to a factor of seven, resulted in significantly fewer reading errors and fixations per sentence, and reduced both the critical print size and the text size required for spot reading by 0.2–0.3 logMAR. We conclude that the level of reading efficiency afforded by the crowding-free reading protocol Word Mode may return reading as a viable activity to many individuals with macular disease

Directional protein secretion by the retinal pigment epithelium: roles in retinal health and the development of age-related macular degeneration

The structural and functional integrity of the retinal pigment epithelium (RPE) is fundamental for maintaining the function of the neuroretina. These specialized cells form a polarized monolayer that acts as the retinal–blood barrier, separating two distinct environments with highly specialized functions: photoreceptors of the neuroretina at the apical side and Bruch's membrane/highly vascularized choriocapillaris at the basal side. The polarized nature of the RPE is essential for the health of these two regions, not only in nutrient and waste transport but also in the synthesis and directional secretion of proteins required in maintaining retinal homoeostasis and function. Although multiple malfunctions within the RPE cells have been associated with development of age-related macular degeneration (AMD), the leading cause of legal blindness, clear causative processes have not yet been conclusively characterized at the molecular and cellular level. This article focuses on the involvement of directionally secreted RPE proteins in normal functioning of the retina and on the potential association of incorrect RPE protein secretion with development of AMD. Understanding the importance of RPE polarity and the correct secretion of essential structural and regulatory components emerge as critical factors for the development of novel therapeutic strategies targeting AMD

Clinical utility of intravitreal fluocinolone acetonide (Iluvien®) implant in the management of patients with chronic diabetic macular edema:a review of the current literature

The first-line therapy for patients with center-involving diabetic macular edema (DME) is with intravitreal anti-vascular endothelial growth factor (VEGF) agents, with or without adjunctive macular laser treatment. However, a significant proportion of patients have persistent and recurrent edema despite repeated anti-VEGF injections. The fluocinolone acetonide (FA) 190 μg intravitreal implant has been shown in pivotal clinical trials to be efficacious for the treatment of DME and has been approved in many countries for use in patients who have not responded to first-line therapy. In this report, we have collated the latest data from the increasing number of studies to illustrate the pattern of usage of the Iluvien FA implant for DME during the current anti-VEGF era. We have shown that there is now a wealth of published evidence from real-world studies to support the clinical utility of the FA implant in achieving further resolution of edema and improving visual acuity outcomes in this challenging group of patients

Bilateral visual outcomes and service utilization of patients treated for 3 years with ranibizumab for neovascular age-related macular degeneration

Background: The aim of this study was to describe bilateral visual outcomes and the effect of incomplete follow-up after 3 years of ranibizumab therapy for neovascular age-related macular degeneration. Secondarily, the demands on service provision over a 3-year period were described. Methods: Data on visual acuity, hospital visits, and injections were collected over 36 months on consecutive patients commencing treatment over a 9-month period. Visual outcome was determined for 1) all patients, using last observation carried forward for missed visits due to early discontinuation and 2) only those patients completing full 36-month follow-up. Results: Over 3 years, 120 patients cumulatively attended hospital for 1,823 noninjection visits and 1,365 injection visits. A visual acuity loss of <15 letters (L) was experienced by 78.2% of patients. For all patients (n=120), there was a mean loss of 1.68 L using last observation carried forward for missing values. Excluding five patients who died and 30 who discontinued follow-up, mean gain was 1.47 L. In bilateral cases, final acuity was on average 9 L better in second eyes compared to first eyes. Also, 91% of better-seeing eyes continued to be the better-seeing eye. Conclusion: We have demonstrated our approach to describing the long-term service provision and visual outcomes of ranibizumab therapy for neovascular age-related macular degeneration in a consecutive cohort of patients. Although there was a heavy burden with very frequent injections and clinic visits, patients can expect a good level of visual stability and a very high chance of maintaining their better-seeing eye for up to 3 years

Characterisation of Malaysian durian (Durio zibethinus Murr) cultivars: relationship of phycochemical and flavour properties with sensory properties

The physicochemical (pH, soluble solids, titratable acidity, sugars and organic acids), flavour and sensory properties of five Malaysian durian cultivars (D2, D24, MDUR78, D101 and Chuk) were studied. There were significant differences (P < 0.05) among the five cultivars in terms of all physicochemical characteristics tested with the exception for D2 and MDUR 78, which had similar physicochemical characteristics. Twenty two esters, 14 sulphur compounds, 7 alcohols, 3 aldehydes and 1 ketone were detected in the durian pulp of the five different cultivars using solid-phase microextraction coupled to gas chromatography-time of flight mass spectrometry. Diethyl disulphide, ethyl-n-propyl disulphide, diethyl trisulphide and ethanethiol were the predominant sulphur-containing compounds in all the cultivars. The major esters present in durian were either ethyl propanoate, ethyl-2-methyl butanoate, or propyl-2-methylbutanoate and their levels varied within cultivars. Principal component analysis applied to the data differentiated all cultivars based on 29 volatile flavour compounds exhibiting significant differences (P < 0.05) between cultivars. Principal components 1 and 2 explained 89% of the total variance. A strong correlation was observed between sensory properties with flavour compound and physicochemical characteristics of the fruit