Application of Visible to Near-Infrared Spectroscopy for Non-Destructive Assessment of Quality Parameters of Fruit

The accuracy and robustness of prediction models are very important to the successful commercial application of visible to near-infrared spectroscopy (Vis-NIRS) on fruit. The difference in physiological characteristics of fruit is very wide, which necessitates variance in the type of spectrometers applied to collect spectral data, pre-processing of the collected data and chemometric techniques used to develop robust models. Relevant practices of data collection, processing and the development of models are a challenge because of the required knowledge of fruit physiology in addition to the Vis-NIRS expertise of a researcher. This chapter deals with the application of Vis-NIRS on fruit by discussing commonly used spectrometers, data chemometric treatment and common models developed for assessing quality of specific types of fruit. The chapter intends to create an overview of commonly used techniques for guiding general users of these techniques. Current status, gaps and future perspectives of the application of Vis-NIRS on fruit are also discussed for challenging researchers who are experts in this research field

The potential of postharvest silicon dips to regulate phenolics in citrus peel as a method to mitigate chilling injury in lemons

This study investigated the ability of silicon dips to enhance the phenolic content in order to reduce the incidence of chilling injury in lemon fruit. Fruits were obtained from two farms and dipped in 0, 50, 150 and 250 mg L-1 solutions of K2SiO3 for 30 min and afterward, fruit were air dried and waxed. Thereafter, fruits were stored at -0.5°C and sampled after 28 days for evaluation of phenolic content and chilling injury symptoms. Chilling susceptible fruit sourced from Ithala farm had significantly lower phenolics and flavonoids concentration when compared with chilling resistant lemons from Ukulinga farm. Phenolic and flavonoids content was improved by dipping fruit in silicon for almost all the concentrations. Moreover, 50 mg L-1 reduced the occurrence of chilling injury symptoms whilst high silicon concentrations increased chilling injury. In conclusion, silicon dips have an ability to reduce chilling injury symptoms in lemons; however, low concentrations should be used.Keywords: Silicon, lemon, antioxidants, phenolics, chilling injuryAfrican Journal of Biotechnology, Vol. 12(13), pp. 1482-148

Characterization of cannabis varieties and the intrinsic and extrinsic factors affecting cannabis germination and seedling establishment: a descriptive review

Cannabis sativa L. is the utmost consumed, grown, and produced illicit drug worldwide. The psychotropic activity of the component (-)-trans-∆9-tetrahydrocannabinol (∆9-THC), however, led to the banning of cannabis worldwide for many centuries. Besides being the most popular crop for recreational purposes, cannabis is grown globally as a multifunctional agricultural crop for its oily seeds and long, durable fibers. These properties have led to cannabis application in various industries, including agriculture, textile, bio-composite, papermaking, automotive, construction, and biofuel. Furthermore, medicinal cannabis constitutes of high concentration of cannabinoids, which have been discovered relevant in the pharmaceutical industry. As a result, various countries worldwide have relaxed regulations on cannabis. However, the cannabis products’ final use depends on the cultivar. Yet, the crop has hundreds of cultivars owing to constant breeding and human selection, which has altered the original plant with the spread of the crop worldwide. Generally, these cultivars possess chemical composition that varies genetically, and with the growing environmental conditions. Therefore, the current descriptive review of literature highlights the techniques available for classifying cannabis varieties, given the ongoing debate over classifying cultivars into distinct taxonomic groups. The effect of intrinsic and extrinsic factors on cannabis germination and seedling establishment are also highlighted

Seed dormancy and germination responses of cannabis landraces to various pre-treatments

The current study evaluated the effectiveness of different pre-treatments for dormancy breaking and seed germination of five cannabis landraces. These landraces were collected from local growers in three regions of KwaZulu-Natal Province in South Africa, namely, Bergville (B), Hammersdale (H), and Ladysmith (L). Each genotype was assigned an alphabet and number based on where the seed material was collected. The five landraces were as follows, ‘B1’, ‘K1’, ‘H1’, ‘L1’, and ‘L2’. The study was conducted using various pre-treatments, including potassium nitrate (KNO3), hydrochloric acid (HCL), hot water (HW) at 70 °C, nitric acid (HNO3), dry prechilling at 10 °C, gibberellic acid (GA3), sulfuric acid (H2SO4), and water, which served as the control. Before the germination test, the seed viability of cannabis landraces was assessed using the tetrazolium chloride (TCC) test. Afterward, the seeds were germinated in Petri dishes with cotton pads moistened with distilled water for five (5) days. The study was later validated under tunnel conditions. The parameters such as germination percentage, germination rate, seedling length, and seed vigour index of the germinated seeds were then measured. The landraces, dormancy breaking treatments, and their interactions showed significant differences (p < 0.001) in germination percentage, germination rate index, seedling length, and seed vigour index under both laboratory and tunnel conditions. In summary, GA3, KNO3 and prechilling were the most effective pre-treatments to improve the germination and seedling growth of cannabis genotypes and breaking seed dormancy. Therefore, it was concluded that cannabis genotypes had physiological dormancy

Mechanism of enhanced freshness formulation in optimizing antioxidant retention of gold kiwifruit (Actinidia chinensis) harvested at two maturity stages

Kiwifruit exhibits a climacteric ripening pattern and has as an extremely perishable nature. Considering that high perishability leads to a loss in antioxidants and overall nutritional quality. This study aimed to examine the efficacy of enhanced freshness formulation (EFF), a hexanal-based formulation containing antioxidants such as geraniol, α-tocopherol and ascorbic acid, on maintaining the bioactive compounds of gold kiwifruit (cv. ‘Y368’) harvested at two maturity stages. Kiwifruits were treated with three treatments, namely, control (untreated fruit), 0.01 and 0.02% (v/v) EFF. Fruits were treated with 8 weeks of cold storage at 0°C and 90% relative humidity, then transferred to 20°C for 8 days. Three bioactive compounds (ascorbic acid, total phenolics and flavonoids), antioxidant capacities using DPPH and FRAP assays, polyphenol oxidase, ascorbate oxidase, phenylalanine and tyrosine ammonia lyase enzyme activities were evaluated. The results showed that EFF significantly (p < 0.05) influenced bioactive compounds, antioxidant capacities and the activity of enzymes involved in the synthesis and oxidation of bioactive compounds. The maturity stage significantly influenced the content of bioactive compounds. Later harvested kiwifruit had greater content of bioactive compounds, compared to earlier harvested kiwifruit. The total phenolic content was 0.77, 1.09 and 1.22 mg GAE g−1 FW for control, 0.01 and 0.02% EFF, respectively. The FRAP antioxidant concentration was 0.76, 0.91 and 0.96 μmol Fe (II) g−1 FW for control, 0.01 and 0.02% EFF. The findings illustrate the capacity of EFF to optimize bioactive compounds and storability of kiwifruit during postharvest storage

Effect of preharvest ethephon application on selected biochemical components and polyphenol oxidase activity in macadamia nuts

Ethephon is a plant growth regulator that triggers diverse responses in plants, such as fruit ripening, leaf senescence, hull senescence, stem elongation, and nut abscission. This study examined how the preharvest application of ethephon 480 SL® affects selected biochemical components and polyphenol oxidase (PPO) activity in two macadamia nut cultivars: ‘788’ and ‘Beaumont’. Ethephon was applied to the trees via a Cima mist blower at rates of 13.33 mL/L per hectare for the ‘788’ cultivar and 16.67 mL/L per hectare for the ‘Beaumont’. Following harvest, the nuts were stored at 25 °C for 72 days, and samples were taken at 18-day intervals. Standard procedures were used to assess the following: total phenolics, total flavonoids, 2,2,-diphenyl-1-picrylhydrazyl (DPPH) assay, Ferric reducing ability power (FRAP) assay, sucrose, total protein, and PPO activities. This evaluation was carried out across a total of four treatments: ethephon-treated nuts from the orchard floor (ED), ethephon-treated nuts from the tree (ET), untreated nuts from the orchard floor (CD), and untreated nuts from the tree (CT). The evaluation’s outcomes were analyzed using a principal component analysis (PCA), a correlation matrix heat map (CMHM), and a graphical assessment. The results unveiled significant correlations and associations among the assessed parameters. The correlation matrix heat map analysis highlighted a strong positive correlation (0.97) between the sucrose and the PPO activity in the ‘Beaumont’ cultivar, supported by the PCA analysis identifying the ED treatment as the most influential. At the storage period’s conclusion, the ED treatment had the highest sucrose content (18.63 mg/g) and polyphenol oxidase activity (1.06 U g−1). In the ‘788’ cultivar, a close relationship emerged between the phenolic content, the PPO activity, and the Ferric reducing antioxidant power (FRAP)’s antioxidant activity. Consistently, the CT treatment (untreated nuts) demonstrated positive correlations with several key parameters in both cultivars, displaying heightened phenolic content and antioxidant activities. Consequently, our findings indicate that the CT treatment, involving tree-harvested nuts without ethephon application, could be the preferred option for sustaining macadamia nuts’ quality and shelf life compared to other methods. Moreover, our study underscores the significance of proper storage conditions for maintaining the desired biochemical parameters of macadamia nuts. By comprehending the effects of distinct treatments and harvesting techniques, producers and processors can devise strategies to optimize storage conditions and uphold macadamia nut quality

Classification of ‘Granny Smith’ apples with different levels of superficial scald severity based on targeted metabolites and discriminant analysis

To study the metabolic changes in ‘Granny Smith’ apples with different severities of superficial scald, fruit were stored in normal refrigerated air (0°C, 95% RH) for 12 weeks followed by 7 d shelf-life under room conditions (20°C, 65% RH). Fruit were graded to five groups based on scald severity and analysed for ethylene, α-farnesene and 6-methyl-5-hepten-2-one (MHO) levels. Reactive oxygen species (ROS) were measured by confocal laser-scanning microscopy on apple peel treated with fluorescent probe 2’,7’-dichlorodihydrofluorescein diacetate. Ethylene production rate, α-farnesene and MHO contents and ROS intensity increased with increasing scald severity but declined in severely scalded fruit. Malondialdehyde (MDA) concentration in fruit peel, a measure of membrane damage, increased linearly (R=0.891) with increase in scald severity. Discriminant analysis was used to classify fruit by scald severity on the basis of metabolites accumulated. The stepwise model indicated that three attributes (ROS, ethylene production and MDA) contributed significantly (R2≥0.5) to the separation of the five scald severity indexes, with ROS having the highest contribution (partial R² =0.961; p<0.0001), followed by ethylene (R2=0.718; p<0.0001) and MDA (R2=0.578; p<0.0001).

The potential of dynamic controlled atmospheres and possible mechanisms in mitigating superficial scald in Apples cv. ‘Granny Smith’

Thesis (PhDAgric)--Stellenbosch University, 2015.ENGLISH ABSTRACT: The development of a postharvest method for controlling superficial scald, maintaining quality and reducing postharvest losses of ‘Granny Smith’ apples is essential in maintaining the competitiveness of the South African apple industry. Previously, the South African apple industry relied on diphenylamine (DPA) for controlling scald disorder; however, increasing consumer concerns and reductions in maximum residue levels (MRLs) have highlighted the urgent need for alternative control strategies. Currently, there is no effective non-chemical method for controlling superficial scald for South African apple producers. The overall aims of this study were (a) to examine the potential of dynamic controlled atmospheres (DCA) in controlling superficial scald in apples, and (b) to investigate the mechanism of action of DCA in controlling scald, should it be effective. To get a deeper understanding of superficial scald etiology and physiological dynamics of apples, studies in paper 2 and 3 were conducted. In paper 2, studies on antioxidants contents and phytochemical properties of apples harvested at pre-optimal and optimal maturity were conducted. Significant increases in fruit antioxidant capacity and ascorbic acid concentration occurred with increasing maturity. Fruit harvested at optimal maturity had lower total phenolic contents compared to pre-optimal maturity. Phenolic compounds including catechin and quercetin were also higher in pre-optimal compared to optimal maturity. In paper 3, an attempt was made to classify apples with different levels of scald severity based on metabolomics analysis. The results showed that ethylene, α- farnesene, 6-methyl-5-hepten-2-one (MHO) and reactive oxygen species (ROS) increased with scald severity but declined in severely scalded fruit. Discriminant analysis successfully classified fruit based on scald severity. Ethylene, ROS and lipid peroxidation were identified as the major contributors in separating the five scald severity levels studied. Studies in paper 4 focused on whether DCA is effective in controlling superficial scald. The minimum period for the exposure of fruit to DCA before an extended shipment period of 10 weeks was also investigated. The results showed that DCA was highly effective in controlling scald for both pre-optimal and optimal harvested fruit. The results further demonstrated that DCA stored fruit can be shipped for 6 weeks; however, extending the shipping period up to 10 weeks might lead scald development and undesired fruit quality. Fruit stored in DCA before shipment generally had higher flesh firmness and ground colour. It was also shown that DCA inhibit scald by retarding the accumulation of scald-associated metabolites such as α-farnesene and MHO. Paper 5 focused on the impact of DCA on ROS, antioxidant capacity and phytochemical properties of stored apples. Using principal component analysis, two clusters which could be identified as DCA and RA stored fruit were noticed. Compared to RA stored fruit associated with higher ROS and lipid peroxidation, fruit stored at DCA was characterized by higher contents of ascorbic acid, total phenolics and antioxidant pool. The research reported in paper 6 investigated the efficacy of repeated application of DCA on apples with high scald potential. During the marketing season, an unexpected demand of fruit often leads to the opening and resealing of storage chambers. Thus, the efficacy of a repeated DCA treatment after an interruption period at RA was investigated. Fruit were stored for up to 16 weeks in DCA with a 14 d interruption in RA at -0.5 °C, 95% RH. The results showed that efficacy of DCA was not significantly affected by the interruption. However, the development of 1% scald after 4 months of storage could be an economic setback for fruit producers. In paper 7, the influence of DCA on aroma volatiles was assessed. DCA stored fruit had significantly lower total amount of volatiles detected compared to fruit stored in RA. Notably, the production of 1-butanol, 1-hexanol and 1-hexenol by fruit stored in DCA were only 42%, 38% and 39%, respectively, of the amounts detected in the RA. The known characteristic flavour of ‘Granny Smith’ apples was attributed to the production of ethyl-2-methylbutyrate, ethyl hexanoate and hexyl acetate. The contribution of these three aroma volatiles was higher with increasing storage duration. In paper 8, the research identified effective variables that could be used to develop prediction models for superficial scald incidence in harvested ‘Granny Smith’ apples. Stepwise multiple regression found MHO, antioxidant capacity (FRAP), ascorbic acid and lipid peroxidation to be the best combination of predictive variables for scald. After validation, this combination gave a good prediction of scald incidence (R2 = 0.94). The identified variables proved to be effective regardless of fruit maturity status. The results from this thesis provide an alternative non-chemical postharvest technology for the South African apple industry. The study further provides insights on the mechanism of action of DCA in controlling scald and maintaining fruit postharvest quality of ‘Granny Smith’ apples. Overall, the results contained in this thesis will be very instrumental in future optimisation of DCA technology in the apple industry, and provides a valuable guide for improved the storage of apples susceptible to superficial scald.AFRIKAANS OPSOMMING: Die ontwikkeling van ’n na-oes metode vir die beheer van oppervlakkige brandvlek, die behoud van gehalte en die vermindering van na-oes verliese van die ‘Granny Smith’ appel is belangrik as Suid-Afrika kompeterend wil bly in die appelindustrie. In die verlede het die Suid-Afrikaanse appelindustrie difenielamien (DPA) benut vir die beheer van oppervlakkige brandvlek maar die groeiende bekommernis van verbruikers en die vermindering in maksimum residuvlakke het die behoefte aan alternatiewe beheerstrategieë beklemtoon. Daar is tans geen alternatiewe nie-chemiese metodes wat Suid-Afrikaanse appelboere kan gebruik om oppervlakkige brandvlek te beheer nie. Die doel met hierdie navorsing is (a) om die potensiaal van dinamies beheerde atmosfeer (DBA) en die beheer van oppervlakkige brandvlek in appels te ondersoek, en (b) om die meganisme van aksie van DBA te ondersoek, indien dit wel effektief bevind word in die beheer van oppervlakkige brandvlek in appels. Die navorsing wat in Artikels 2 en 3 opgeteken is, is gedoen om ’n dieper begrip van oppervlakkige brandvlek etiologie en die fisiologiese dinamika van appels te bekom. In Artikel 2 is die bevindings oor die chemiese kenmerke van appels wat geoes is by preoptimale en optimale oesrypehied, opgeteken. Betekenisvolle vermederinge in die vrugte se antiodatiewe status en askorbiensuur konsentrasie vind met volwassenheid plaas. Vrugte wat by optimale rypheid geoes word het ’n laer totale fenoliese inhoud vergeleke met vrugte wat by pre-optimale volwassenheid gepluk word. Fenoliese samestellings insluitende catechin en quercetin is ook hoër by volwasse vrugte. In die navorsing wat in Artikel 3 opgeteken is, is daar gepoog om appels met verskillende vlakke van brandvlek deur middel van metabolomiese analise te klassifiseer. Die resultate toon dat etileen, α-farnesene, 6-metiel-5- hepten-2-een (MHO) en die reaktiewe suurstof spesie (RSS) toeneem hoe erger die brandvlek raak maar afneem in erg gebrandvlekde vrugte. Die vrugte is suksesvol geklassifiseer volgens hoe erg die brandvlek voorgekom het deur middel van onderskeidende ontledings. Etileen, RSS en lipied peroksidasie is identifiseer as die hoof bydraers tot die onderskeiding van die vyf brandvlek vlakke wat bestudeer is. In die studie wat in Artikel 4 opgeteken is, is die fokus op of dinamiese beheeranaliese, oppervlakkige brandvlek doeltreffend kan beheer. Die minimum periode vir die blootstelling van vrugte aan dinamies beheerde atmosfeer voor ’n uitgebreide verskepings periode van 10 weke is ook ondersoek. Die resultate toon dat dinamies beheerde atmosfeer hoogs effektief is in die beheer van brandvlek beide in vrugte wat voor die optimale tyd of op die optimale tyd geoes is. Die resultate het ook getoon dat vrugte wat in ’n dinamies beheerde atmosfeer gestoor is, vir ses weke verskeep kan word; maar dat as die periode tot tien weke verleng word, brandvlek kan ontwikkel en die gehalte van die vrugte kan afneem. Vrugte wat voor verskeping in DBA gestoor is, is fermer en die agtergrondkleur is beter behou. Daar is ook getoon dat DBA brandvlek ontmoedig deur om die akkumulasie van metaboliete wat met brandvlek geassosieer word, soos α-farnesene en MHO te verminder. In Artikel 5 is die fokus op die impak van DBA op RSS, antioksidant vermoë en die fitochemiese kenmerke van gestoorde appels. Deur om die hoofkomponente te ontleed is twee groepe wat as DBA en verkoelde lug (RA) gestoorde vrugte identifiseer is, uitgeken. In vergelyking met vrugte wat onder RA toedtande gestoor is, en wat geassosieer was met hoë ROS en lipied peroksidasie, is vrugte wat in DBA gestoor is, gekenmerk deur ’n hoër askorbiensuur inhoud, totale fenoloë en oksidante. In Artikel 6 is die bevindings van ’n ondersoek na die doeltreffendheid van herhaaldelike toepassing van DBA op appels met ’n hoë brandvlek potensiaal, opgeteken. Dit gebeur dikwels dat daar gedurende die markseisoen ’n onverwagte vraag na vrugte ontstaan en dat die stoorkamers dan oopgemaak en weer verseël word. Dus is die doeltreffendheid van herhaaldelike DBA behandeling na ’n periode van RA ondersoek. Vrugte is vir tot 16 weke in DBA gestoor met ’n onderbreking van 14 dae in RA teen -0.5 °C, 95% RH. Die bevindinge het bewys dat die doeltreffendheid van DBA nie merkbaar deur die onderbreking aangetas is nie. Die ontwikkeling van 1% brandvlek na 4 maande in die stoorkamers mag egter deur die produsente as negatief beskou word. In Artikel 7, word die invloed van DBA op die aromtiesevlugtige stowwe geassesseer. Vrugte wat in DBA gestoor is, het ’n merkbaar laer totale hoeveelheid aromatiese vlugtige stowwe getoon, in vergelyking met vrugte wat in ’n RA gestoor is. Die produksie van 1-butanol, 1-heksanol en 1-heksen-ol in vrugte wat in DBA gestoor is, is egter net 42%, 38% en 39%, onderskeidelik van die wat in RA gestoor is. Die kenmerkende geur van ‘Granny Smith’ appels is die gevolg van die produksie van etiel-2- metielbutyraat, etiel heksanoate and heksiel asetaat.Die bydrae van hierdie drie aromatiese vlugtige stowwe was hoër na’n uitgebreide stoortydperk. In Artikel 8 word die navorsing beskryf wat doeltreffende veranderlikes identifiseer wat gebruik kan word om voorspellingsmodelle vir die hoeveelheid van oppervlakkige brandvlek in geoesde ‘Granny appels’ te ontwikkel. Deur stapsgewyse veelregressie is daar gevind dat MHO, antioksidant vermoë, askorbiensuur en lipiede peroksidasie die beste kombinasie is vir die voorspellende veranderlikes vir brandvlek. Nadat dit geldig gevind is, het hierdie kombinasie ’n goeie voorspelling vir die voorkoms van brandvlek (R2 = 0.94) verskaf. Die geïdentifiseerde veranderlikes was effektief vir alle vrugte, sonder inagneming van volwassenheid. Die bevindinge van hierdie navorsing verskaf ’n alternatiewe niechemiese na-oes tegnologie vir die Suid-Afrikaanse appelindustrie. Verder is nuwe insigte bekom in die meganismes van aksie van DBA wat betref die beheer van brandvlek en die behoud van na-oes gehalte van ‘Granny Smith’ appels. In die geheel sal die bevindinge van hierdie tesis bydra tot die toekomstige optimalisering van DBA tegnologie in die appelindustrie, en waardevolle riglyne verskaf word vir die verbetering van die stoor van appels wat vatbaar is vir oppervlakkige brandvlek

Adoption Drivers of Improved Open-Pollinated (OPVs) Maize Varieties by Smallholder Farmers in the Eastern Cape Province of South Africa

This study assesses the determinants of adoption drivers of improved open-pollinated (OPVs) maize varieties by smallholder farmers in the Eastern Cape Province of South Africa. Cross-sectional data of multi-stage random sampling was used to randomly select 150 smallholder farmers in the province. Data collection was conducted through a well-structured questionnaire administered to 150 smallholder farmers. Descriptive statistics and a logistic regression model were used for the analyses. The inferential results reveal that the majority of farmers in the study area were females (70%) with an average age of 45 years and had six people in the households. Smallholder maize farmers spent an average of 10 years in school. The results show that smallholder maize farmers had a farm size of 3 ha and a household income of R 3565.00, which contributes highly to household and farm operations. Farmers had access to extension services and were members of farm organizations. The results show that hybrid is the most used maize variety rather than OPVs. The main reason, among other things, for the poor use and adoption of OPVs is the lack of knowledge about the seeds. The results drawn from the estimations show that socio-economic and institutional factors influenced the adoption of OPVs by farmers in the study area. Therefore, the study recommends strengthening the existing extension services to highlight the benefits of OPVs through training and farmers’ information days

Adoption Drivers of Improved Open-Pollinated (OPVs) Maize Varieties by Smallholder Farmers in the Eastern Cape Province of South Africa

This study assesses the determinants of adoption drivers of improved open-pollinated (OPVs) maize varieties by smallholder farmers in the Eastern Cape Province of South Africa. Cross-sectional data of multi-stage random sampling was used to randomly select 150 smallholder farmers in the province. Data collection was conducted through a well-structured questionnaire administered to 150 smallholder farmers. Descriptive statistics and a logistic regression model were used for the analyses. The inferential results reveal that the majority of farmers in the study area were females (70%) with an average age of 45 years and had six people in the households. Smallholder maize farmers spent an average of 10 years in school. The results show that smallholder maize farmers had a farm size of 3 ha and a household income of R 3565.00, which contributes highly to household and farm operations. Farmers had access to extension services and were members of farm organizations. The results show that hybrid is the most used maize variety rather than OPVs. The main reason, among other things, for the poor use and adoption of OPVs is the lack of knowledge about the seeds. The results drawn from the estimations show that socio-economic and institutional factors influenced the adoption of OPVs by farmers in the study area. Therefore, the study recommends strengthening the existing extension services to highlight the benefits of OPVs through training and farmers&rsquo; information days