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• Phytohormonal changes in relation to citrus rind disorder was examined postharvest. • Fruit were harvested from inside and outside canopy position of the tree. • Endogenous levels of cytokinins (CK), auxins, isomers and conjugates were analysed. • Cis -zeatin-type CK concentrations were higher in outside canopy fruit postharvest. The role of phytohormones in mitigating or enhancing the incidence of non-chilling rind physiological disorder of citrus fruit is largely unknown. Therefore, this study attempted to elucidate cytokinins (CK) and auxin changes in 'Nules Clementine' mandarin fruit rind from different canopy positions during postharvest non-chilling cold storage regarding rind breakdown disorder (RBD). Fruit from the inside canopy (IC) and outside canopy (OC) positions of citrus trees were harvested at commercial maturity from Eastern Cape (EC) and Western Cape (WC) provinces of South Africa, respectively. Endogenous levels of CK, auxins, their isomers, and conjugates were analysed using ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer (MS/MS) equipped with an electrospray interface. Cis -zeatin-type cytokinins were significantly higher in the OC fruit than in the IC fruit from both provinces during cold storage. Whereas dihydrozeatin concentration (the most abundant CK) was significantly higher in fruit from IC (326.10 and 29.38 nmol kg−1) than in OC (65.75 and 17.72 nmol kg−1) fruit before cold storage, respectively. Fruit without rind disorder had lower CK - conjugates than fruit with the disorder. The IAA concentration was higher in the IC fruit (344.15 nmol kg−1) than in the OC fruit (194.20 nmol kg−1) from EC at week 0 while the IAA concentration of OC fruit from WC was below the limit of detection and IC fruit had 53.20 nmol kg−1 at week 0. Fruit without the disorder had more IAA concentration than fruit with RBD while indole-3-acetylaspartic acid (IAAsp) was higher in fruit with RBD than fruit without the disorder, indicating the preventive role of IAA in the incidence of the disorder. This study is the first to record the negative effect of IAAsp in RBD and revealed the crucial role and synergistic role of CK, IAA and their isomers in RBD of 'Nules Clementine' fruit. [ABSTRACT FROM AUTHOR]

For decades, producers, researchers, and food safety agencies have faced the challenge of processing bitter citrus fruit and making it more appealing to consumers. The primary compounds responsible for the bitterness in citrus fruit juices are naringin and limonin. In order to extend the shelf life and enhance the acceptability of citrus fruit juices, similar to other tropical fruits, scientists and the food industry have been continuously working to reduce their bitterness. This has led to the development of various physical, chemical, and biological methods, which are commonly used scientific approaches for reducing bitterness in citrus fruit juices. This review emphasizes the significance of citrus fruit in the economy and discusses the different bittering agents present in citrus fruits, as well as the various techniques used to detect their presence. Additionally, it highlights different debittering techniques and the advancement of technologies aimed at achieving fast, reliable, and effective debittering of bitter citrus fruits. The review also examines the effects of different debittering techniques on the chemical and phytochemical properties of citrus juice and briefly discusses future prospects in this field. Furthermore, this review recognizes the potential of advanced techniques such as sensors to replace traditional methods. Traditional approaches often require a significant amount of time and technical expertise and can be expensive. The utilization of sensors and other advanced technologies can address these limitations and provide more efficient and cost-effective solutions in the debittering process. [ABSTRACT FROM AUTHOR]

• Photosynthetic efficiency of leaves from different positions of avocado trees was assessed. • Outside leaves had higher photosynthetic rate and stomatal conductance. • The high photosynthetic efficiency of outside fruit was linked fruit maturity. • Outside fruit matured earlier with mesocarp DM content of 23.2% compared to 22.3% on inside fruit. Physiological changes associated with leaf chlorophyll fluorescence and gas exchange are the key components towards understanding performance of fruit trees. In this study, the photosynthetic efficiency of leaves from inside and outside canopy positions of avocado trees was assessed during the fruit growing season. The aim was to determine to what extent photosynthesis and gas exchange of the leaves correlates with the position of the leaf inside canopy and outside canopy of an avocado tree, and how does that affect fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa during 2017/18 season. A total of fifteen 8-year old avocado trees (cv. 'Carmen') were selected in a completely randomised design with three replicates and each replicate consisting of five trees. Data was collected bi-weekly from full bloom to fruit physiological maturity (25% dry matter content). Measured variables included gs, C i, T , A , F 0 , F m , Fv/Fm , ΦPS II , qP, qN, ETR, 1- qP and DM content, were estimated within and outside canopy. Results showed that leaves from the outside position had higher A (22.28 mol CO 2 m−2 s−1) , gs (0.22 mol CO 2 m−2 s−1) , ΦPS II (0.35), and qP (0.57) compared to those on the inside position of the canopy with lower values of 14.19 mol CO 2 m−2 s−1, 0.14 mol CO 2 m−2 s−1, 0.047 and 0.071, for A, gs, ΦPS II and qP respectively. Conversely, Fo', Fm' , Fv', Fv'/Fm' , and 1- qP were about two times higher on the inside canopy than on the outside. The high photosynthetic efficiency of outside fruit was linked fruit maturity with fruit from the outside maturing earlier with an average mesocarp dry matter content of 27.6% compared to 26.5% on fruit from the inside canopy. The findings suggest that the high sunlight interception by leaves from the outside position improved photosynthetic efficiency, increased rate of dry matter accumulation and maturation of avocado fruit. There is a strong sink demand within the outside canopy demanding more carbohydrates, and thus commanding leaves from the outside canopy to photosynthesize more efficiently leading to fast maturity. [ABSTRACT FROM AUTHOR]

The physicochemical properties of citrus fruit play critical roles in its maturity and quality determination. Hence, this study investigated the effect of canopy position on physicochemical properties of ‘Marsh’ grapefruit across different production regions at harvest and after storage at 7.5 °C for 3, 6, and 9 weeks. The study also evaluated the use of BrimA as an adoptable internal quality and maturity parameter for ‘Marsh’ grapefruit. Fruit from inside canopy (IC) and outside canopy (OC) were harvested from KwaZulu-Natal (KZN) and Mpumalanga (MP) provinces in South Africa. Titratable acidity was determined by titration and calculation of the sugar/acid ratio (TSS/TA) was established while BrimA was derived from sugar and acid with tongue sensitivity index. Colour indices were measured using calibrated colorimeter while sugars were measured using high performance liquid chromatography (HPLC). At harvest, IC fruit from MP province were more luminous than the OC fruit while inverse results were recorded for fruit from KZN. At harvest, IC fruit had higher percentage of titratable acidity (TA) (2.73%) than OC fruit (2.40%) from MP, with opposite results from KZN. The BrimA showed a strong and positive correlation with TSS/TA (r = 0.9364). Overall, our result suggested that canopy position affect some physicochemical properties of ‘Marsh’ grapefruit. However, harvested fruit displayed a high level of maturity and quality over the period of cold storage. BrimA could potentially be used as an index of internal quality of grapefruit but further studies into the subject is required. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of a low-cost evaporative cooling system and its effect on postharvest storage potential and physicochemical quality properties of tomatoes. The performance of the cooling system was evaluated in terms of temperature drop, increase in relative humidity (RH) and cooling efficiency. Two tomato cultivars (‘9065′ jam and round) were harvested from smallholder farms in Umsinga, South Africa (28˚45′56.45′'S, 30˚33′42.37′'E). Tomatoes were assigned to one of the three storage conditions namely; evaporative cooling system (ECS), cold room (CR) and room temperature (RT). Quality parameters evaluated included mass loss, respiration rate, colour, firmness, total soluble solids and titratable acids for both tomato cultivars. ECS reduced temperature to 19.8 °C which was 13% lower than RT (23.0 °C). RH increased from 63.59% in RT to 83.91% in the ECS with an average cooling efficiency of 67.17%. Storage treatments and time had significant ( p  <  0.05) effect on fruit quality. Fruit in the CR retained colour, mass, firmness, respiration rate, TA and TSS of both cultivars longer than the other treatments. However, the ECS was able to preserve the freshness of tomatoes for 20 days and had a slower rate of change in mass, respiration, colour, firmness, TA and TSS compared with those stored at RT. This suggested that the evaluated ECS is capable of maintaining postharvest quality and increasing shelf-life of tomatoes. Therefore, ECS has a potential as a low-cost and energy-free system for preserving quality and reducing postharvest losses under smallholder farming systems. [ABSTRACT FROM AUTHOR]

Rind biochemical concentrations and radical-scavenging activities of ‘Nules Clementine’ mandarin could play a significant role in the susceptibility of the fruit to various forms of physiological rind disorders. This study examined the effect of fruit position within tree canopy on biochemical concentrations and radical-scavenging activities of ‘Nules Clementine’ mandarin fruit rind after harvest at week 0 and after 3, 6 and 9 weeks of postharvest cold storage at 7.5 ± 0.5 °C. Biochemical concentrations and radical-scavenging activities of flavedo and albedo tissues of the rind were also examined. Fruit from inside canopy (IC) and outside canopy (OC) were harvested at commercial maturity in May 2015 and 2016 from Unifruiti and Swartvelei Farms located at Eastern Cape (EC) (33° 27′ 32″ S, 25° 34′ 79″ E) and Western Cape (WC) (19° 02′ 33.8″ S, 33° 41′ 17.24″ E) provinces of South Africa, respectively. Results showed that canopy position played a significant ( p < 0.001) role on total carotenoids, total phenolics and total flavonoids as well as rind dry matter, with OC fruit often characterised by higher biochemical concentrations than IC fruit during cold storage. The study further showed that production region influenced radical-scavenging activities and carbohydrate content of OC and IC fruit rind during cold storage. Radical-scavenging activities of OC fruit (61.2%) were higher than IC fruit (52.5%) from EC whereas radical-scavenging activities of IC fruit (67.1%) were higher than those of OC fruit (58.2%) from WC at harvest. Overall, this study revealed that fruit position within tree canopy influenced its rind biochemical concentrations and radical-scavenging activities. [ABSTRACT FROM AUTHOR]

This study investigated the potential of edible carboxyl methylcellulose (CMC) containing moringa leaf and seed extracts as a novel postharvest treatment for maintaining storage quality and controlling diseases in ‘Hass’ and ‘Gem’ avocado fruit. The study also investigated the antifungal activity of methanolic and ethanolic moringa plant extracts. Briefly, 1% CMC was blended with 2% of moringa leaf (MLE) or seed extract (MSE). After the fruit was dipped in either CMC + MLE or CMC + MSE, it was stored at 5.5 °C (95% RH) for 21 days. After cold storage, fruit were stored at ambient conditions (21 ± 1 °C) and 60% RH to simulate retail conditions. Postharvest quality attributes such as ethylene production, respiration rate and fruit firmness were measured. Both coatings were also tested against postharvest fungi in reference to potato dextrose agarose (PDA). Coated fruit had lower mass loss, ethylene production and respiration rate compared to the uncoated fruit. Ethanolic leaf extract had an inhibition of 43.6% and 42.9% against C. gloeosporioides and A . alternata , respectively. Scanning electron microscopy analysis revealed damaged hyphal structures for all pathogens exposed to coatings while such structures remained intact in uncoated fruit. Ethanolic moringa leaf extracts proved to have higher antimicrobial activity compared to methanolic extracts. The findings reported in this study demonstrated that CMC containing moringa extract suppresses diseases, prolongs the shelf-life and maintain the overall quality avocados during postharvest supply chain. The CMC blended with moringa extracts could potentially be commercialized as a new organic edible coating for avocado fruit industry. [ABSTRACT FROM AUTHOR]

Vitamin C is widely regarded as one of the most important antioxidants in citrus fruits. The rapidly growing demand for fresh citrus fruits and their derivative products has prompted researchers to study factors affecting the vitamin C content. This review discusses postharvest factors influencing vitamin C content of citrus fruits. Vitamin C content in citrus fruits can be influenced by several factors such as postharvest treatment, storage conditions as well as oxidative stress. Postharvest treatments such as surface coating, heat treatments, irradiation, and ethylene degreening lead to better vitamin C retention. Additionally, improper temperature management may negatively affect the nutritional quality of the stored produce; vitamin C loss is intensified at higher storage temperatures. Although storage conditions favorable to water loss are known to accelerate vitamin C loss, the effect of low relative humidity (RH) on vitamin C content of citrus fruits has not yet been fully elucidated. Vitamin C retention is also improved when citrus fruits are stored in modified atmosphere packaging and controlled atmosphere (CA). Although the effect of postharvest treatments on vitamin C content has been intensively studied, the influence of chemical treatments warrants more research. [ABSTRACT FROM AUTHOR]

Citrus fruits are an important diet for human health by providing some nutritional and antioxidant components, especially ascorbic acid (AsA). As the major antioxidant compound, the concentration of AsA is an important nutritional quality indicator for citrus fruit and its derivative products. Although the emphasis is on vitamin C content of harvested citrus fruit, this review of literature focuses on preharvest factors affecting this nutritional quality variable. The literature reviewed in this study showed that the content of AsA in citrus fruits is influenced by numerous preharvest factors including genotype, cultural practices, climatic conditions, fruit maturity and postharvest management. To better understand the mechanism underlying the vitamin C content of different citrus fruits, the introduction of this paper will first provide an overview of major proposed biosynthetic pathways and genes encoding for enzymes involved in AsA biosynthesis and oxidation. The review will then concentrate on the current state of knowledge regarding inherent genetic, environmental, fertilization, maturity and harvesting factors affecting AsA of citrus fruits. Some suggestions for future research are also highlighted. [ABSTRACT FROM AUTHOR]

The rapidly growing organic food market has prompted many researchers to compare numerous aspects of organically and conventionally grown foods. This review of literature provides an overview of empirical studies comparing postharvest quality of organically and conventionally produced fruits. The emphasis is on key postharvest quality parameters including physicochemical properties, postharvest storage performance, microbiological, sensory and nutritional quality. The study showed that physicochemical and nutritional properties relating to the contents of vitamins, phenolics and antioxidants are higher in organically produced fruits. It is also showed that production system has little effect on sensory quality. The better taste of organic produce as perceived by consumers is only due to the ‘halo effect’ of the organic label. The differences identified could be largely attributed to the different fertilization systems between organically and conventionally managed soils. The microbial contamination due to improper use of manure and compost in organically managed soils is a major concern in organic fruits. High levels of pesticide residues and nitrates in conventionally grown fruits is also a cause of concern. Several important problems in organic fruits are yet to be addressed, bacterial and fungal contamination of organic fruits warrants more intensive research. Future research should also investigate the effect of production system on storage potential. [ABSTRACT FROM AUTHOR]

The determination and quantification of sugars is important for quality control and assurance of horticultural produce. This review discusses analytical methods for determination of sugars and sweetness of fresh and processed fruit and vegetables, including the use of destructive and non-destructive instrumental techniques to evaluate sugar composition and characterize taste profile or sweetness. From the standard hand-held refractometer to the hydrometer, electronic tongue and high pressure liquid chromatography (HPLC) equipped with different detectors, a wide range of devices have been used to determine sugar composition and sweetness of many fruit and vegetable products. Although chromatographic techniques are very accurate and useful, they require extensive sample preparation based on solvent extraction and hence are generally time-consuming and expensive. Visible to near infrared spectroscopy (vis/NIRS) has been proposed as an interesting alternative to traditional methods due to its rapidity, simplicity, cost effectiveness and potential for routine analysis if proper calibration and validation steps were developed. Current trends favour analytical methods that are simple to use, quick and non-destructive. The prospects for using emerging technologies such as hyperspectral imaging and nuclear magnetic resonance for non-destructive assessment of sugar content and sweetness of fresh and processed horticultural food products are also discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fruit from inside the canopy were more susceptible to RBD disorder than outside fruit. [•] Vis/NIRS PLS models predicted rind fructose, glucose and sucrose with accuracy. [•] Vis/NIRS PCA model was able to non-destructively classify fruit based on tree canopy. [•] Models based on pre-storage spectra gave better prediction of RBD than post-storage. [Copyright &y& Elsevier]

Highlights: [•] X-ray CT was used to non-destructively evaluate internal structures of pomegranate fruit. [•] Image analysis algorithm to compute volume of arils, albedo and air spaces was developed. [•] Characterization of fruit with and without chilling injury was achieved using X-ray CT. [Copyright &y& Elsevier]

Highlights: [•] Vis/NIRS models for prediction of mandarin postharvest rind quality were validated. [•] Rind carbohydrates associated with rind breakdown disorder were predicted. [•] Spiking of models with few samples from prediction set improved model performance. [•] The robustness of PLS models across two seasons and four orchards was demonstrated. [•] Models developed using collective data of all orchards and seasons performed better. [Copyright &y& Elsevier]

Highlights: [•] A link between fruit canopy position and rind biochemical profile was established. [•] Bagged fruit inside the canopy had higher incidence of rind breakdown disorder. [•] Shaded fruit had lower rind dry matter and higher postharvest weight loss. [•] Vis/NIRS PCA displayed clusters that separated fruit according to canopy position. [Copyright &y& Elsevier]

Highlights: [•] The mechanism of citrus rind breakdown (RBD) disorder was studied. [•] Reduced light inside tree canopy exacerbated RBD incidence. [•] Fruit inside canopy with low sugar concentrations in the rind were more susceptible to RBD. [•] Postharvest water loss is an important factor leading to RBD. [Copyright &y& Elsevier]

Highlights: [•] A non-destructive method for evaluating microstructures of citrus rind was developed. [•] Real-time image acquisition was achieved with optical coherence tomography (OCT). [•] Rind breakdown disorder was associated with the progressive collapse of oil glands. [•] Image processing procedures to compute volume and 3D models of oil glands were demonstrated. [Copyright &y& Elsevier]

The objective of this study was to determine drought tolerance of diverse potato (Solanum tuberosum L.) genotypes. The physiological and morphological responses of eight potato genotypes were assessed under well-irrigated (Wi) and deficit irrigation (Di) conditions across four different growth stages, namely, the Vegetative (VG), Tuber Initiation (TI), Tuber Bulking (TB) and maturity (MAT) stages, using an 8 × 4 × 2 factorial treatment structure with three replications. Data were collected on morphological traits such as Plant Height (PH), the Number of Leaves (NL), Tuber Yield (TY) and Total Above-Ground biomass (TAG), as well as the physiological traits such as stomatal conductance (gs), Transpiration rate (Tr), the rate of photosynthesis (A), Water Productivity (WP), Chlorophyll Content Index (CCI) and Relative Water Content (RWC). A significant (p < 0.05) genotype x water condition x growth stage effects were observed for A , Tr, WP, RWC, CCI, PH, NL, TY and TAG, which indicated the varied responses of the genotypes to the water conditions across the growth stages. This is useful when recommending the growth-stage specific and drought tolerant potato genotypes for production. Correlation analysis revealed significant and negative association between gs and WP with TY (r = −0.81; r = −0.77) at the VG stage, positive association between PH, Tr, A and WP with TY (r = 0.92; r = 0.65; r = 0.95; r = 0.88) at the TI stage.CCI positively correlated with TY (r = 0.71) at the MAT stage, and a negative association was observed between TAG with TY (r = −0.85) at the MAT stage, under Di conditions. Principal component bi-plot identified that the all-rounder genotypes that are resistant to drought in all stages include the Challenger, Sifra and Tyson. These genotypes are recommended for cultivation in water-restricted environments. • Drought tolerance of potato genotypes was evaluated by imposing water deficit. • Varied responses of genotypes to water deficit across growth stages were observed. • Genotypes with higher water use efficiency and high yield were the most tolerant. • Bikini and Challenger had higher tuber yield regardless of growth stage for water deficit. • Bikini and Challenger are recommended for cultivation in water-restricted conditions. [ABSTRACT FROM AUTHOR]

• Growth and yield response of hydroponic tomato to wastewater nutrient sources was investigated. • Plants fertilized with the commercial hydroponic mix had higher growth rate and low harvest index. • Fertigation with wastewater improved physiological performance and leaf nutrient composition. Disposal of human excreta derived materials (HEDM), particularly domestic wastewater, presents a challenge in areas served with on-site sanitation systems, most particular in informal settlements. The use of HEDM for agricultural food production represents a couple of opportunities such as improved sanitation, household food security as well as the generation of informal income. In this study, tomato seedlings 'Monica' cv were grown in a hydroponic system and irrigated with HEDM (effluents from decentralized wastewater treatment system and nitrified urine concentrate). A commercial hydroponic fertilizer mixture was used concurrently as a control treatment. All the treatments were applied to the plants through fertigation using a drip irrigation system. Plant growth (plant height, stem diameter, leaf area index, root:shoot ratio and plant dry matter), physiological (photosynthesis and chlorophyll), yield components (fruit number, fruit mass, harvest index and crop yield), leaf nutrient composition (N, P, K, Mg, Ca, Cu, Mn, Fe, Zn and Na) and microbiological (Aerobic count, coliforms and faecal coliforms) parameters were measured to assess the potential of these HEDMs as nutrient sources for hydroponically produced tomatoes. The results showed that irrigating the tomatoes with HEDM increased harvest index relative to crops irrigated with a commercial hydroponic fertilizer mix. Tomato plants irrigated with a commercial hydroponic fertilizer mix achieved the highest growth and yield, however, irrigation with human excreta based sources improved plant physiological performance and leaf nutrient composition compared to crops irrigated with commercial fertilizer mix. In terms of microbiological analysis, tomatoes harvested from plants treated with HEDM recorded the highest population of bacterial count as compared to the commercial hydroponic fertilizer mix.These results showed that nutrients derived from human excreta can be a good source of nutrients for hydroponically grown tomatoes. Moreover this practice can effectively address the challenges of human waste disposal while at the same time providing the much-needed resources for increased food production through urban agriculture. However, further research on the effect of heavy metals, pathogens on tomato fruit quality is still needed for the adaptation of wastewater as nutrients sources for hydroponically grown tomatoes. [ABSTRACT FROM AUTHOR]

• Photosynthetic response of hydroponic tomato to waste-based nutrient sources was investigated. • Plants fertilized with the commercial hydroponic mix had higher leaf area index. • Tomato treated with nitrified urine concentrate had higher chlorophyll content. • Leaves of tomatoes treated with DEWATS effluent had higher photosynthetic rate. There is increasing interest and wide recognition of the potential use of human-excreta derived materials (HEDM) as fertilizer to supply essential nutrients needed for crop production. However, most work on HEDM has focussed on yield responses using soils and very little done on soil-less media using hydroponics. Further, physiological responses of plants to different HEDM in a hydroponic production system is currently not well-understood. This study investigated the effect of Decentralized Waste-water Treatment System (DEWATS) effluents and Nitrified Urine Concentrate (NUC) on leaf gas exchange, photosynthetic efficiency and mineral content of hydroponically-grown tomato. The experiment was conducted in a polyethylene tunnel using a complete randomised design comprising of three treatments namely: DEWATS effluent, NUC and commercial hydroponic fertilizer mix (CHFM). Sampling conducted both before and after flowering showed significant differences (P < 0.05) among different nutrient sources for all physiological parameters (leaf gas exchange and chlorophyll fluorescence) and mineral content. Leaf N and P were significantly (P < 0.05) higher in NUC treatment whereas Ca and K were high in the CHFM treatment. The current study demonstrated that HEDM such as NUC and DEWATS effluent could be an effective source of nutrients of agricultural crops in hydroponic systems with results comparable to commercial fertilizer mix. [ABSTRACT FROM AUTHOR]

• The effect of canopy position on biochemical compounds regulating avocado maturity and ripening was evaluated. • Outside fruit had higher dry matter (DM) and oil content resulting in earlier maturity. • Higher concentrations of C7 sugars were recorded on inside canopy fruit, coinciding with late maturity and ripeness. • The minimum maturity of fruit from the inside canopy guarantees the maturity of outside canopy fruit. In the current study, biochemical changes of avocado fruit cv. 'Carmen' and 'Hass' were evaluated during growth, development and maturation. The aim was to determine if exposure of fruit to sunlight could vary the biochemical compounds associated with maturity, and hence be among the causes of uneven maturity, and ripening. The current study also seeks to evaluate if the mesocarp C7 sugars, oil and DM content have a relationship with fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa. Nine avocado fruit (cv. 'Carmen' and 'Hass' avocado) per canopy were sampled bi-weekly for assessment of mesocarp dry matter (DM), oil content, D -mannoheptulose, perseitol and total C7 sugars. The significantly (p < 0.001) higher DM and oil content in fruit that were sampled from the outside canopy in both cultivars suggested an early maturity, and vice versa inside canopy. The higher D- mannoheptulose and perseitol in fruit sampled inside canopy as a storage reserve was associated with the rate of respiration, which is slower inside canopy due to cooler temperatures. This results in accumulation of higher overall C7 sugars that are slowly used up as a substrates of respiration for synthesis of overall DM, oils, proteins, C6 sugars and other biochemical constituents associated with ripening. In terms of maturity, higher D -mannoheptulose and perseitol implies that fruit from the inside canopy will take longer to mature and to reach edible ripeness when harvested. This then causes uneven maturity of fruit, only characterized by uneven ripening. [ABSTRACT FROM AUTHOR]

• Photoprotection mechanisms of avocado leaves from tree canopy positions were assessed. • Photochemistry was high outside of and low within the tree canopy. • Photoprotection mechanisms were stronger within the canopy and poorer outside the canopy. • High photochemistry outside the canopy was linked to early fruit maturity. • High chlorophyll fluorescence and heat dissipation within the canopy delayed fruit maturity. A reduction in photosynthesis results in a reduced CO 2 assimilation rate and availability of carbohydrates essential for fruit growth and development. This study determined photosynthetic efficiency and photoprotection mechanisms within and outside leaf canopy positions in 'Gem' avocado orchards and their relationship with avocado fruit maturity. The study was conducted in a commercial orchard at Everdon Estate in KwaZulu-Natal, South Africa. A total of 15 eight-year-old avocado trees (cv. Gem) were selected in a completely randomised design with three replicates, with each replicate consisting of five trees. Data were collected bi-weekly on photosynthetic rate (A), effective quantum efficiency of photosystem II (ϕPSII), stomatal conductance (gs), transpiration rate (T), electron transport rate (ETR), minimum fluorescence (Fo'), maximum fluorescence (Fm'), variable fluorescence (Fv'), intrinsic water use efficiency (WUE i), instantaneous water use efficiency (WUE ins), intercellular CO 2 concentration (Ci) and photochemical quenching (qP) from full bloom to fruit physiological maturity (∼25 % dry matter content (DM)). The results showed that leaves from the outside position had higher A (29.46 mol CO 2 m−2s-1); gs (0.078 mol CO 2 m−2s-1); ΦPS II (0.32); and qP (0.52) compared to those within the canopy position with lower A (19.27 mol CO 2 m−2s-1); gs (0.0037 mol CO 2 m−2s-1); ΦPS II (0.044) and qP (0.075), respectively. Contrastingly, chlorophyll fluorescence and photoprotection parameters were higher within the canopy than on the outside, suggesting that the greater proportion of energy accumulated within the canopy was used for photoprotection other than photochemistry. Photosynthetic rate (A) , gs, Ci, T, WUEi and WUE ins , correlated significantly with mesocarp dry matter (DM), while all other parameters correlated poorly. The high photosynthetic efficiency of leaves from outside the canopy resulted in an average DM of 28.9 % compared to 26.9 % of fruit within the canopy. The present findings suggest that reduced photosynthetic efficiency of 'Gem' avocado within the canopy position does not compromise fruit DM by reserving more energy for photoprotection; however, it delays maturity by about two weeks. [ABSTRACT FROM AUTHOR]

Water scarcity, nutrient-depleted soils and pollution continue to be a major challenge worldwide and these are likely to worsen with increasing global populations particularly, in urban areas. As a result, environmental and public health problems may arise from the insufficient provision of sanitation and wastewater disposal facilities. Because of this, a paradigm shifts with regard to the sustainable management of waste disposal in a manner that could protect the environment at the same time benefits society by allowing nutrient recovery and reuse for food production is required. Hence, the use of urban wastewater for agricultural irrigation has more potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for crop production. Among the current treatment technologies applied in urban wastewater reuse for agriculture, hydroponic system is identified as one of the alternative technology that can be integrated with wastewater treatment. The integration of hydroponic system with municipal wastewater treatment has the advantage of reducing costs in terms of pollutants removal while reducing maintenance and energy costs required for conventional wastewater treatment. The efficiency of a hydroponic system with regard to municipal wastewater reuse is mainly linked to its capacity to allow continuous use of wastewater through the production of agricultural crops and the removal of pollutants/nutrients (nitrogen and phosphorus), resulting to increased food security and environmental protection. Moreover, the suitability of hydroponic system for wastewater treatment is derived from its capacity to minimize associated health risks to farmers, harvested crop and consumers, that may arise through contact with wastewater. Unlabelled Image • Wastewater disposal is exacerbated by the increasing population and rapid urbanization. • A paradigm shift towards sustainable management of waste disposal was identified. • Nutrient recovery and use for food production in hydroponic system is an alternative. • Advances of technologies to recover nutrients for food crop production is provided. [ABSTRACT FROM AUTHOR]

Fourier transform near infrared (FT-NIR) diffuse reflectance spectroscopy as a non-destructive method for the development of calibration models has been investigated as a means of assessing the quality of whole pomegranate fruit. FT-NIR diffuse reflectance spectrometers with different spectral acquisition modes were evaluated using direct contact between the sample and the integrating sphere (IS), or by a contact-less measurement using an optic fibre coupled emission head (EH) to scan fruit over a distance of 170 mm. Fruit weight, firmness and colour components (a*, Chroma, hue angle), total soluble solids (TSS), pH, titratable acidity (TA), sugar to acid ratio (TSS:TA), BrimA, total phenolics, total anthocyanin and vitamin C. The best prediction statistics obtained from calibration models of the EH were firmness (R 2  = 83.0, residual predictive deviation (RPD) = 2.43), fruit colour components (a*: R 2  = 90.9, RPD = 3.34); Chroma: R 2  = 83.0, RPD = 2.43, TSS (R 2  = 78.1, RPD = 2.17), TA (R 2  = 76.8, RPD = 2.12), BrimA (R 2  = 76.2, RPD = 2.08), total phenolics (R 2  = 88.0, RPD = 2.91) and vitamin C (R 2  = 76.2, RPD = 2.06). The best prediction obtained from calibration models of IS were colour component Hue (R 2  = 83.9, RPD = 2.50), TSS:TA (R 2  = 86.8, RPD = 2.72) and total anthocyanin (R 2  = 62.6, RPD = 1.64). Overall, good prediction was observed for both the EH and IS; however, better prediction performance was obtained with the EH which gave the best prediction for 9 of the 13 quality parameters evaluated. These findings have demonstrated that the EH (a contactless option of the Matrix-F) can be implemented as an online tool for the analysis of pomegranate fruit quality. [ABSTRACT FROM AUTHOR]

Postharvest RP is a progressive rind physiological disorder affecting citrus fruit during postharvest storage, reducing external quality of the fruit. The disorder develops 3–5 weeks after harvest, making it difficult to detect during grading and sorting in commercial packing lines. The Vis/NIR spectroscopy and associated chemometric analytical methods were explored for non-destructive prediction of ‘Marsh’ grapefruit ( Citrus x paradisi MacFad) susceptibility to rind pitting. Reflectance Vis/NIR spectral data was acquired from fruit, just after harvest, using a laboratory bench-top monochromator NIR System equipped with a quartz halogen lamp and lead sulfide detector. Reference measurements for calibrating and validating PLS models included visual scores of RP and rind physico-chemical variables related to the disorder. The spectral data was correlated to RP scores and rind physico-chemical properties after eight weeks in cold storage and a week in shelf life. Good prediction of RP was obtained (R 2 p  = 0.78; RPD = 2.03; RMSEP = 1.41). Prediction models for rind physicochemical properties successfully developed and validated included rind total antioxidant capacity (R 2 p  = 0.95), β carotene (R 2 p  = 0.99), total carotenoids (R 2 p  = 0.92), chlorophyll a (R 2 p  = 0.89), chlorophyll b (R 2 p  = 0.93), dry matter (R 2 p  = 0.88), sucrose (R 2 p  = 0.91), glucose (R 2 p  = 0.93) and fructose (R 2 p  = 0.94). Principal component analysis successfully segregated fruit based on canopy position and susceptibility to rind pitting disorder. The ability of Vis/NIR spectroscopy coupled with chemometric analysis to cluster fruit based on canopy position is recommended as a secondary approach to discriminate fruit with high susceptibility to RP since RP occurrence was high on fruit from outside canopy. [ABSTRACT FROM AUTHOR]

Fruits with thick rind have been reported to interfere with the measurement of internal quality of non-destructive near infrared spectroscopy. This review provides an overview of issues related to the use of near infrared spectroscopy for measuring internal and external quality attributes of horticultural produce with thick rinds. The use of other non-destructive techniques for assessing internal and external quality thick rind fruit, such as hyperspectral and multispectral imaging systems, X-ray micro-computed tomography, nuclear magnetic resonance and Raman spectroscopy are also discussed. A concise summary of research and potential commercial application for each of the techniques is highlighted. [ABSTRACT FROM AUTHOR]

In this study, X-ray computed tomography (CT) was used as a non-destructive technique to characterise and quantify the internal structure of pomegranate fruit (cv. Wonderful). A commercial X-ray system with a radiation source of 245 kW and electron current of 300 μA was used to generate two-dimensional (2D) radioscopic images which were reconstructed into three dimensional (3D) images for the quantification and volume estimation of internal structural components of fruit. Segmentation of the internal fruit components (arils, peel, kernel, juice content, air space) and single arils was achieved using StudioMax volume graphics software. The calculated volume of each fruit fraction were 162.5 ± 16.2, 163.9 ± 21.4, 16.4 ± 1.8, 10.9 ± 2.6 mL for arils, peel, kernel and air space, respectively which accounted for 48.1, 48.3, 4.9 and 4.1% of total fruit volume. Furthermore, the calculated volume of juice content was 146.1 ± 16.3 mL per fruit which was equivalent to an average of 89.8% of total aril weight, while a single aril (0.3 ± 0.04 mL) accounted for only 0.09% of whole fruit volume. Destructive validation measurements of each fruit fraction showed similar results to non-destructive data, with volumes of 163.3 ± 15.2, 161.8 ± 20.6, 15.1 ± 1.6, and 12.3 ± 4.4 mL for arils, peel, kernel, air space, respectively, while volumes of juice and single aril were 142.7 ± 16.4 and 0.3 ± 0.09 mL per fruit, respectively. Furthermore, the results showed that fruit physical attributes such as length, diameter and peel thickness were underestimated by an average of 0.14%, 1.13% and 5.27%, respectively, while fruit radius was overestimated by 1.75%. Nevertheless, no significant differences were observed for length, diameter, radius and peel thickness between X-ray CT predicted values and actual measurements. This work has demonstrated the capability of X-ray CT as a non-destructive technique to suitably estimate the fruit volume and its fractions which could be employed for fruit quality systems. [ABSTRACT FROM AUTHOR]

Harvest maturity of avocado fruit is currently determined using indices such as mesocarp oil content, dry matter (DM) or moisture content (MC), both measured destructively using representative samples of a batch in an orchard. Although useful, destructive techniques are time-consuming and results reflect properties of specific produce evaluated. In this study, the feasibility of near-infrared spectroscopy (NIRS) as a rapid non-destructive method for predicting maturity parameters of individual avocado fruit was evaluated. NIRS prediction results showed that MC and DM were predicted accurately, with residual predictive deviation (RPD) of 2.00 and 2.13 respectively. However, models for predicting oil content, though promising, were not accurate, with RPD value of less than 1.0. The good prediction statistics between NIRS predicted MC and DM content demonstrated the potential of this system for non-destructive evaluation of avocado fruit maturity status. The stability and accuracy of models developed over two seasons, 2013 and 2014, to predict maturity parameters of avocado fruit demonstrated model robustness. NIRS combined with PLS models developed in this study are recommended for non-destructive evaluation of individual avocado fruit maturity status. [ABSTRACT FROM AUTHOR]

Long-term cultivation of citron watermelon under water - constrained environments in sub-Saharan Africa resulted in the selection and domestication of highly tolerant genotypes. However, information on the magnitude of variation for drought tolerance in citron watermelon is limited for the effective selection of suitable genotypes for breeding. The objective of this study was to determine variation for drought tolerance among South African citron watermelon landrace accessions for selection and use as genetic stock for drought-tolerance breeding in this crop and closely-related cucurbit crops. Forty genetically differentiated citron watermelon accessions were grown under non-stress (NS) and drought-stress (DS) conditions under glasshouse environment. Data of physiological (i.e., leaf gas exchange and chlorophyll fluorescence parameters) and morphological traits (i.e., shoot and root system architecture traits, and fruit yield) were collected and subjected to various parametric statistical analyses. The accessions varied significantly for assessed traits under both NS and DS conditions which aided classification into five groups, namely; A (highly drought-tolerant), B (drought-tolerant), C (moderate drought-tolerant), D (drought-sensitive) and E (highly drought-sensitive). Drought-tolerant genotypes produced more fruit yield with less water compared with drought-sensitive genotypes. Several physiological and morphological parameters correlated with fruit yield under DS condition namely: instantaneous water - use efficiency (r = 0.97), leaf dry weight (r = 0.77), total root length (r = 0.46) and root dry weight (r = 0.48). The following accessions, namely: WWM-46, WWM-68, WWM-41(A), WWM-15, WWM-64, WWM-57, WWM-47, WWM-37(2), WWM-79, WWM-05 and WWM-50) were identified as highly drought-tolerant and recommended for drought-tolerance breeding in this crop or related cucurbit crops such as sweet dessert watermelon. [Display omitted] • Morphological, physiological and agronomic traits were used to assess drought tolerance of 40 citron watermelon accessions. • Morphological traits used were, leaf area, specific leaf area and root phenes. • Physiological traits used were, leaf gas exchange and chlorophyll fluorescence parameters. • Accessions varied significantly for assessed traits under both non-stress and drought-stress conditions. • Hierarchical clustering identified 11 accessions as highly drought-tolerant and recommended for drought-tolerance breeding. [ABSTRACT FROM AUTHOR]

• Roasted macadamia kernels had high concentration antioxidants, and unsaturated fatty acids. • Roasted nuts displayed low levels of polyphenol oxidase (PPO), peroxide value (PV). • Strong correlations were observesd between ratio of PUFA:MUFA and sensory quality. • Roasting can alter fatty acid profile of the nuts depending on the roasing temperature. Raw and roasted kernels of 'A4' and 'Beaumont' macadamia cultivars were assessed for biochemical and sensory quality during the accelerated storage of 70 days. Kernels were roasted at 125 °C for 15 min using a hot air oven dryer. Roasted kernels had significantly (p < 0.001) high concentration of phenols, antioxidants and good sensory properties: aroma, taste and overall appearance, validated by low levels of polyphenol oxidase (PPO), peroxide value (PV) and fatty acids (FAs) at the end of storage. Whereas, raw kernels had high and unacceptable levels of PPO, PV and FA compositions which accelerated the rancidification process, supported by low concentration of phenols, antioxidants and poor aroma. A strong correlations were observesd between ratio of polyunsaturated FA: monounsaturated FA (PUFA:MUFA) and sensory quality attributes (aroma and appearance) for roasted cultivars before storage. And also positive correlation was observed among PV, rancidity and cultivars which indicate that raw 'Beaumont' and roasted 'A4' macadamia nuts after 70 days of storage had higher PV values, resulting to rancidity taste. Roasting can alter fatty acid profile of the nuts depending on the roasing temperature. These findings demonstrate that roasting can improve macadamia nuts' quality as compared to raw nuts, but the roasting temperature regime needs to be determined for different cultivars. [ABSTRACT FROM AUTHOR]

Highlights • This review shows moisture and oil contents are used for nut quality evaluation. • Fatty acid composition and rancidity are major determinants of nut quality. • Non-invasive analytical methods for evaluating quality of nuts have become popular. • Vis/NIRS is the utmost promising non-destructive technology for future application. • Research is required to test hyperspectral imaging and X-ray-CT for nut quality evaluation. Abstract Moisture content (MC), oil content (OC), fatty acid composition and rancidity are considered as major determinants of quality of nuts. These parameters are destructively quantified from a batch of representative samples used to estimate quality of nuts of an entire orchard. Although destructive techniques are helpful, they involve extensive sample preparation and solvent extractions, are slow, expensive and obtained results specifically reflect the properties of the evaluated produce. Recently, non-invasive analytical methods and instruments for evaluating quality of various produce have become popular with researchers putting more effort in developing them. Non-destructive methods are an alternative to traditional methods for inspection of internal quality parameters because they are fast, simple and cost-effective. In this review, invasive and non-invasive analytical methods and instruments for evaluating MC, OC, fatty acid composition and rancidity in different nuts are discussed. This paper also reviews the implementation of visible to near infrared spectroscopy, nuclear magnetic resonance and X-ray computed tomography on nuts for evaluation of quality attributes. Technical challenges and future possibilities for commercial use of these non-invasive methods for quality evaluation of nuts are presented. [ABSTRACT FROM AUTHOR]

Sweetness and flavour are desirable attributes used for quality control and assurance of citrus fruit, which are largely determined by total soluble solids (TSS), titrable acidity (TA) and TSS: TA ratio. However, the accuracies of TSS, TA and TSS: TA as flavour indices have been recently criticised. BrimA (Brix minus acids), on the other hand, is an accurate organoleptic parameter that has been shown to be highly related to sweetness and flavour of citrus fruit. In this study, the ability of visible to near infrared spectroscopy (Vis/NIRS), in reflectance mode, to non-destructively quantify BrimA, TSS, TA and TSS: TA ratio of ‘Valencia’ orange and ‘Star Ruby’ grapefruit was evaluated. Vis/NIR spectral data was acquired using a laboratory bench-top monochromator NIR Systems. Reference measurements and spectral datasets were subjected to partial least square (PLS) regression analysis. The best prediction models were observed for BrimA of ‘Valencia’ oranges with the coefficient of determination (R 2 ) = 0.958; root mean square error of prediction (RMSEP) = 0.006 and residual predictive deviation (RPD) = 3.96, followed by TSS: TA ratio (R 2 = 0.958; RMSEP = 0.605; RPD = 4.92). Good models for predicting flavor of grapefruit were also attained, with TSS having the best model (R 2 = 0.896, RMSEP = 0.308 and RPD = 2.94), followed by BrimA (R 2 = 0.858; RMSEP = 0.429; RPD = 2.45). These results demonstrated the ability of Vis/NIRS to non-destructively predict sweetness and flavour attributes of oranges and grapefruit. Vis/NIRS was recommended as a possible fast and accurate technique to be used for fruit discrimination based on flavour parameters during packing and for pricing of fruit in the market. [ABSTRACT FROM AUTHOR]