BIOCHEMICAL AND PHYSICOCHEMICAL PROPERTIES OF FOUR MANGO VARIETIES AND SOME QUALITY CHARACTERISTICS OF THEIR JAMS

Ripening associated antioxidant and phytochemical changes in mango (Mangifera indica) cultivar Dusehri

The phytochemical fingerprinting that add to the nutritional and nutraceutical value of the fruits during the ripening stages is beneficial for human consumption. Therefore, ripening-dependent changes in phytochemical content and antioxidant activities of mango (Mangifera indica L.) cultivar Dusehri at various ripening stages were evaluated. Bioassays for phenolic content, flavonoid content, antioxidant activities, and UHPLC/MS for phytochemical profiling was performed at five ripening stages (RSI-RSV). Total phenolic contents significantly increased from 4.25 to 13.08 µg GAE/mg extract upto stage III and non-significant decrease was observed thereafter. Flavonoid contents varied between 1.16 and 1.23 µg QE/mg extract. DPPH based free radical scavenging activity increased (41.07-52.33%) from stage I to stage V while FRSP based analysis showed decrease (53.01-27.61 µg TE/mg extract) in activity from stage I to stage V. Total antioxidant capacity and total reducing power potential of pulp extract gradually increased towards mango ripening stages. A non-significant change in amylase inhibition was observed from stage I to stage III that significantly dropped in stage IV and V. UHPLC analysis depicted that aconitic, methylisocitric, 2,4,6-Hydroxy benzoic acid and beta glucogallin, poly phenols, 1-Methylxanthine, 3-Furicacid, Heptenoic acid and many others are present at different ripening stages of dusehri mango. PCA analysis and hierarchal analysis show Stage I & II clustering while stages III-V make separate cluster. These phytochemiclas are responsible for many health benefits. The study concludes that dusehri mango have significant antioxidative capacity that are due to diverse phytochemicals.

Larval and adult diet affect phenotypic plasticity in thermal tolerance of the marula fly, Ceratitis cosyra (Walker) (Diptera: Tephritidae)

Introduction

Temperature fluctuations are important for the distribution and survival of insects. Rapid hardening, a type of phenotypic plasticity, is an adaptation that can help individuals better tolerate lethal temperatures because of earlier exposure to a sublethal but stressful temperature. Nutrition and sex are also known to influence a species ability to tolerate thermal stress. This study determined the effects of larval diet, adult diet, sex and hardening on the thermal tolerance of Ceratitis cosyra (Walker) (Diptera: Tephritidae) at lower and upper lethal temperatures.

Methods

Larvae were raised on either an 8% torula yeast (high) or a 1% torula yeast (low) larval diet and then introduced to one of three dietary regimes as adults for thermal tolerance and hardening assays: no adult diet, sugar only, or sugar and hydrolysed yeast diet. Flies of known weight were then either heat- or cold-hardened for 2 hours before being exposed to a potentially lethal high or low temperature, respectively.

Results

Both nutrition and hardening as well as their interaction affected C. cosyra tolerance of stressful temperatures. However, this interaction was dependent on the type of stress, with nutrient restriction and possible adult dietary compensation resulting in improved cold temperature resistance only.

Discussion

The ability of the insect to both compensate for a low protein larval diet and undergo rapid cold hardening after a brief exposure to sublethal cold temperatures even when both the larva and the subsequent adult fed on low protein diets indicates that C. cosyra have a better chance of survival in environments with extreme temperature variability, particularly at low temperatures. However, there appears to be limitations to the ability of C. cosyra to cold harden and the species may be more at risk from long term chronic effects than from any exposure to acute thermal stress.

Adult diet does not compensate for impact of a poor larval diet on stress resistance in a tephritid fruit fly

Adult holometabolous insects may derive metabolic resources from either larval or adult feeding, but little is known of whether adult diets can compensate for deficiencies in the larval diet in terms of stress resistance. We investigated how stress resistance is affected and compensated for by diet across life stages in the marula fruit fly Ceratitis cosyra (Diptera: Tephritidae). Larvae were fed diets containing either 8% torula yeast, the standard diet used to rear this species, or 1% yeast (low protein content similar to known host fruit). At emergence, adults from each larval diet were tested for initial mass, water content, body composition, and desiccation and starvation resistance or they were allocated to one of two adult diet treatments: sucrose only, or sucrose and yeast hydrolysate. The same assays were then repeated after 10 days of adult feeding. Development on a low protein larval diet led to lower body mass and improved desiccation and starvation resistance in newly emerged adults, even though adults from the high protein larval diet had the highest water content. Adult feeding decreased desiccation or starvation resistance, regardless of the diet provided. Irrespective of larval diet history, newly emerged, unfed adults had significantly higher dehydration tolerance than those that were fed. Lipid reserves played a role in starvation resistance. There was no evidence for metabolic water from stored nutrients extending desiccation resistance. Our findings show the possibility of a nutrient-poor larval environment leading to correlated improvement in adult performance, at least in the short term.

Assessing Nutritional Traits and Phytochemical Composition of Artisan Jams Produced in Comoros Islands: Using Indigenous Fruits with High Health-Impact as an Example of Biodiversity Integration and Food Security in Rural Development

In the Comoros Islands, as in other developing countries, malnutrition and food insecurity affect a very large percentage of the population. Developing fruit-based products in order to make profit, reduce poverty and improve indigenous people diet could be very important for local population of countries as Comoros Islands. The aim of the present work was to study the chemical composition of jams and jellies produced from seven fruit species harvested in Grand Comore Island. The following parameters were studied sugars and organic acids, total phenolics, total anthocyanins and high-performance liquid chromatography (HPLC) fingerprint of the main phytochemicals. Antioxidant activity was also measured. A multivariate approach (Principal Component Analysis) was performed in order to better characterize the products and to set a potential analytical tool for jam characterisation. Results showed that the analysed products are a good source of polyphenolic constituents, as caffeic and gallic acids, catechin and quercetin and volatile compounds, as limonene and γ-terpinene: these molecules may be considered as suitable markers for these fruit-derived products as characterizing the chromatographic patterns. The characterisation of these products and their nutritional and nutraceutical traits is important as valorisation of local food production for poverty reduction and rural development. Further benefits of this approach include the maintenance of local agro-biodiversity as raw material for fruit-based products and the strengthening of food security practices.

Hygroscopic properties and glass transition of dehydrated mango, apple and banana

An undesirable crispiness loss occurs when some dry fruits reach a critical moisture content (X_c ) and their glass transition temperature (T_g ) matches the storage temperature. Models for sorption isotherms and onset T_g values for dry mango, apple, and banana were used to estimate X_c values at 25 and 32 °C. All models yielded R² > 0.97 but information theory criteria strongly supported GAB in all but one case (40 °C, mango). The Gordon-Taylor T_g model (GT) yielded high R² values for apple and banana but resulted in R² = 0.834 for mango. As moisture approached zero, mango T_g estimates displayed a downward concavity contrasting with a rapidly increasing trend for apple and banana. The Khalloufi-Maslouhi-Ratti (KMR) model for T_g as a function of a_w showed a linear behavior. Although the KMR model fitted data with R² > 0.996, it requires more parameters and when a_w approached 0, estimated T_g values increased at a slower rate than for the GT model. In the case of banana and mango, both models predicted approximately the same X_c at 25 °C but not at 32 °C. Finally, all X_c values estimated based on T_g were lower than the monolayer values obtained with the GAB (apple and banana) and BET (mango) models. These results indicate that the glass transition induced by moisture uptake dominates the quality degradation of these dry fruits.

Study of mango endogenous pectinases as a tool to engineer mango purée consistency

The objective of this work was to evaluate the possibility of using mango endogenous pectinases to change the viscosity of mango purée. Hereto, the structure of pectic polysaccharide and the presence of sufficiently active endogenous enzymes of ripe mango were determined. Pectin of mango flesh had a high molecular weight and was highly methoxylated. Pectin methylesterase showed a negligible activity which is related to the confirmed presence of a pectin methylesterase inhibitor. Pectin contained relatively high amounts of galactose and considerable β-galactosidase (β-Gal) activity was observed. The possibility of stimulating β-Gal activity during processing (temperature/pressure, time) was investigated. β-Gal of mango was rather temperature labile but pressure stable relatively to the temperature and pressure levels used to inactivate destructive enzymes in industry. Creating processing conditions allowing endogenous β-Gal activity did not substantially change the consistency of mango purée.