Interactions between vegetative and generative growth and between crop generations in fig tree (Ficus carica L.)
Yield in fruit trees strongly depends on the balance between vegetative growth and fruiting. This balance is particularly complex in fig tree (Ficus carica L.); in which two generations of figs (Breba and Main crop) develop along an annual shoot and compete with two consecutive growth seasons. For better understanding the interaction between vegetative growth and fruiting in this species; we studied their dynamics throughout three growth seasons on five fig cultivars grown in center-east Tunisia. Shoot elongation was measured at regular intervals from mid-March until mid-December and the number of reproductive buds and fruits were counted at four dates each year.In all cultivars; annual shoot extension exhibited two consecutive phases with unequal duration; separated by a growth cessation. Reproductive buds and fruits number were closely dependent on shoot length. Significant positive correlations were found between Breba crop figs number of current season and shoot length of previous season (0.83 = r = 0.98) and between Main crop figs number of current year and shoot length of current season (0.83 = r = 0.95). The Main crop amount exerted a strong influence on the current shoot growth as well as on fruiting in the following year: a heavy Main crop load of current season reduces vegetative growth and crop load of Breba for the next year. Similarly; high Breba crop load negatively affected the Main crop load for the current year. The results support the idea of the close interaction between vegetative and reproductive growth in each fig generation and growth flush. By contrast; the strong competition between fig generations appears to be indirect and mediated by the competition between vegetative and reproductive growth. A synthetic scheme of the complex interactions that govern fig generations and vegetative growth rhythmicity in the fig tree is proposed. The data are discussed in terms of the opportunities to manipulate tree growth to enhance fruiting efficiency of fig tree.
Effect of pollination intensity; frequency and pollen source on fig (Ficus carica L.) productivity and fruit quality
Yield and fruit quality in fig (Ficus carica L.) are highly dependent on cultural practices especially caprification (pollination). However; this technique remains not well controlled in Tunisia. This study was conducted during two successive years; 2009 and 2010; to investigate different pollination conditions; i.e. number of caprifigs and repetitions of caprification on fruiting of two cultivars Bouhouli (San Pedro type) and Zidi (Smyrna type). In addition; the efficiency of four pollen sources was evaluated to identify the most effective pollinator for female cultivar Zidi. The following parameters were recorded: fruit number per shoot; fruit set; productivity; fruit characteristics and vegetative growth. Results indicated that caprification realized at four times with an interval of 4 days between each time could be efficient to improve fruit set (74.1 and 70.8% for Bouhouli and Zidi; respectively) and fruit quality (112 g per fruit ; 19.4°Brix for Bouhouli; and 102 g per fruit ; 20.3°Brix for Zidi). Compared with others caprifigs; the pollen of caprifig Djebba 2 resulted in higher productivity (6 fruits /20 cm); fruit weight (75.6Â83.8 g); a large flesh thickness (23Â25.1 mm) and better taste of fruits (16°Brix and 0.18% titrable acidity). These results suggested that caprifig Djebba 2 should be selected as the adequate pollinator for the edible Zidi fig in north-west Tunisia. Highlights: Caprification at four times was effective for improving productivity and quality of fig fruits. The increase of pollination frequency had significant effect on measured parameters. The use of the caprifig Djebba 2 could be very interesting for the caprification of cultivar Zidi.
Chemical and aroma volatile compositions of date palm (Phoenix dactylifera L.) fruits at three maturation stages
Abstract: The effect of maturity stage on the physicochemical composition and volatile components of date palm fruits (Phoenix dactylifera L.) was investigated at three different stages. Total sugars; pH; proteins and ash increased up to the full-ripe stage of all date types. On the contrary; weight; moisture and total lipids decreased across the same period. PearsonÂs test established significant differences (p < 0.05) between the different cultivars at each stage for all the parameters. Furthermore; multivariate tests shows that the composition and the variation of the chemical compositions mainly depended on the cultivar kind. Eighty volatile compounds were identified during the maturation stages; 43 of them were newly identified in Tunisian date fruits. The profiles of volatile compounds seem to be similar for Degla and Horra varieties. Results from this work revealed essential information about the richness of littoral cultivars in many nutrients and the possibility of their uses as a functional food ingredient.
Date syrup: effect of hydrolytic enzymes (pectinase/cellulase) on physico-chemical characteristics; sensory and functional properties.
Abstract: This work is a contribution to give value addition to second grade dates (with hard texture) by the production of enzymatically treated syrup with high commercial value. It was observed that the pulp: water at ratio 1:3 treated with 50 U of pectinase and 5 U of cellulase during 120 min at 50°C gave the highest recovery of total soluble solids (72.37 g of total soluble solids /100g fresh basis) and the lower turbidity (186.45 NTU) compared with control without enzyme addition (Total soluble solids yields: 66.34 g of total soluble solids /100g fresh basis and turbidity: 1513 NTU). Physicochemical measurements indicated that carbohydrates were predominant in all date varieties as well as their syrups ( 69.59-83.76 g/100g dry matter in dates and  62.14-74.68 g/100 g fresh weight in syrup). Allig variety was characterised by a high content of reducing sugars content ( 77.91 g/100g dry matter); contrary to deglet Nour ( 23.17 g/100g dry matter) and Kentichi ( 21.3 g/100g dry matter). The CIE L* a* b* colour values of the enzyme-treated date syrup of Deglet Nour; Allig and Kentichi variety showed lighter colours (L* values ranging from 24.16 to 44) than the control without enzyme (L* values ranging from 0.545 to 17.2). Hedonic evaluation showed that enzyme-treated date syrup was more appreciated by consumers. Microbiological study showed that date syrups were free from aerobes; molds; coliforms and enterobacteriaceae and were microbiologically stable during five months storage. Results suggested that enzymatic treatment could be used for production of date syrup with high commercial value.
Preliminary characterization of food tablets from date (Phoenix dactylifera L.) and spirulina (Spirulina sp.) powders.
Abstract: In this work; some physical properties (hardness; friability; disintegration time and erosion) of food tablets containing various food powders obtained from dates (Phoenix dactylifera L.); spirulina (Spirulina sp.) and oranges (juice and zest) were investigated. Also; experimental data related to the release kinetic of phycocyanin (antioxidant substance of spirulina) into different liquid mediums; correctly fit the Korsmeyer-Peppas model since the coefficient of determination R2 ranged from 0.84 (HCl 0.1N solution) to 0.98 (distilled water). So; the date and spirulina powders-based food tablets could be of various uses: 1) consumption as such by all categories of consumers; 2) feeding of patients for whom it is difficult to chew or swallow food; knowing that these tablets can be either sucked or swallowed; 3) as natural and cheap drug delivery carriers. Research Highlights: Valorization of the date fruit with low commercial value and its processing into powder and than in food tablets; Food value of these tablets is improved with the addition of spirulina known for its high nutritional value (protein rich-material); Spirulina does not have an agreeable flavor which is then hidden when added to the powder to date powder. The presence of juice and orange peel enhance the taste of the tablets some properties of tablets obtained show that they are suitable to certain categories of patients with eating difficulties: easy disintegration at pH of the mouth; the dissolution testing of phycocyanin; shows that it is released slowly; which promotes its therapeutic action as anti-inflammatory; the physical properties of tablets obtained (hardness; friability; erosion; dissolution testing) permit to use the tablets obtained in the pharmaceutical industry as carriers of active ingredients. The cost of the tableting process is very low: the varieties used and others are sometimes used as animal feed in Algerian Sahara because they do not sell well.
The effect of genotype and roasting on the fatty acid composition of peanuts.
The impact of two factors; genotype (G) and treatment (raw or roasted peanut) (T); on the chemical composition of peanuts was studied using a chemometric method and Tukey's test. The peanut genotypes evaluated were cultivar cavalo vermelho (CCV); cultivar cavalo rosa (CCR) and cultivar tatu (CTA); in both raw and roasted states. The total lipid contents in the CTA and CCR peanuts were 40 and 45%; respectively. These values did not vary significantly (p<0.05) after roasting. CCV had the greatest total lipid content; but it decreased significantly after roasting (from 50% to 45%). The variation in the percentage of lipids in the CCV and CCR genotypes was not significant; in contrast to the CTA genotype. The fatty acid (FA) 18:1n-9 predominated in the CCR and CCV samples (50%); without any difference between their raw genotypes. The values for FA 18:1n-9 were lower in the CTA peanut (40%). The second most abundant FA was 18:2n-6 (CCV=28%; CTA=38% and CCR=25%); followed by 16:0 (CCV and CCR=16% and CTA=11%). The other FAs found in the peanuts were 18:0; 20:0; 22:0; 24:0; 20:1n-9 and 18:3n-3. The contents of FAs 18:1n-9; 16:0; 20:0; and 20:1n-9 suffered significant reduction after roasting in all genotypes. ANOVA analysis of the influence of the main factors indicated that the contribution of the T variable for the majority of responses was low; being between 0.2 and 13%; except for FAs 16:0 and 18:3n-3 and for the saturated FA summations; which were 38; 60 and 22%; respectively. There was a significant contribution from the G factor for all responses; with values between 17 and 99%. The contribution of the interaction between the T and G factors was greater for the responses n6/n3 (56.6%) and for the FA 16:0 (23%). The other responses had values between 0.02 and 14%.
Effect of drying methods on physico-chemical and antioxidant properties of date fibre concentrates
Effects of different drying methods (freeze-; oven- and sun-drying) on physico-chemical properties of date fibre concentrates (DFC) from three potential Tunisian cultivars were investigated. DFC had high contents of dietary fibre (71.01Â93.46% dry matter); with high proportions of insoluble dietary fibre. Freeze dried DFC had the highest values of swelling; water holding and oil holding capacities. This drying method gave also the lightest DFC colour. Kentichi fibre produced by freeze-drying had the highest viscosity and the lowest bulkier particles. The present work assessed polyphenol content and antioxidant activity of DFC using 1;1-diphenyl-2-picrylhydrazyl (DPPH) method. The highest polyphenol content was found for freeze dried DFC; contrary to radical scavenging activity which was not affected by drying methods. Results suggest that freeze dried DFC had the highest potential to be used as a functional ingredient in food products.
Walnut (Juglans regia L.): genetic resources; chemistry; by-products
Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry; productivity; physical and chemical nut traits. Some of them have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg(-1) in some commercial varieties); which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols; phospholipids; sphingolipids; sterols; hydrocarbons and volatile compounds. Phenolic compounds; present at high levels in the seed coat but poorly extracted with the oil; have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine; glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics.
The influence of roasting; pasteurization; and storage on the polyphenol content and antioxidant capacity of California almond skins
Polyphenols and antioxidant activity of skins from California almonds subjected to roasting; pasteurization; and storage were determined by LC-MS quantification; total phenols (TP); and ferric reducing antioxidant power (FRAP). Pasteurization did not significantly change TP; FRAP; or flavonoids and phenolic acids (FP). Roasted almonds had 26% less TP and 34% less FRAP than raw; but equivalent FP (n = 12). Storing almonds at 4 and 23°C for 15 mo resulted in gradual increases in FP; up to 177 and 200%; respectively (n = 13). At 4°C and 15 mo; polyphenols increased 18-fold for p-hydroxybenzoic acid; while others were 45 to 200% higher compared to baseline values. Isorhamnetin-3-O-rutinoside accounted for 48% of the increase in FP. After 15 mo; FRAP and TP increased to 200 and 190% of initial values. Accelerated aging of whole almonds increased FP content by 10% after 3 days; but TP and FRAP values were not significantly different from baseline to day 10. Thus; in almond skins; roasting decreases TP and FRAP but not FP; while storage for up to 15 mo doubles FP.
Phenolic compounds and antioxidant activity of Brazil nut (Bertholletia excelsa)
Brazil nuts were shelled and separated as kernel and brown skin; whole nuts were also used. Soluble phenolics from each portion as well as the whole nut were extracted using 70% acetone under reflux conditions. Insoluble-bound phenolics were subsequently extracted into diethyl etherÂethyl acetate mixture (1:1; v/v) after alkaline hydrolysis. Both soluble and insoluble-bound phenolic extracts were separately examined for their total phenolics content; antioxidant activities were evaluated by trolox equivalent antioxidant capacity (TEAC); 1;1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activities using electron paramagnetic resonance (EPR); reducing power; and oxygen radical scavenging capacity (ORAC). Soluble phenolics in brown skin was 1236.07 as compared to 406.83 in kernel and 519.11 mg/100 g in whole nut. Bound phenolics content of brown skin was also 86- and 19-folds higher than kernel and whole nut; respectively. Similarly extracts from the brown skin exhibited the highest antioxidant activity. Free- and bound phenolics were identified and quantified; these included nine phenolic acids and flavonoids and their derivatives (gallic acid; gallocatechin. protocatechuic acid; catechin; vanillic acid; taxifolin; myricetin; ellagic acid; and quercetin). However; some phenolics were present only in the bound form. Furthermore; the phenolics were dominant in the brown skin.