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The aim of this work was to evaluate the quality of Hass avocado submitted to application of propolis and vegetable wax. The selected fruits were submitted to the treatments (1) without wax and without propolis, (2) with vegetable wax, (3) propolis alcoholic extract 100%, (4) wax and etanol 70%, (5) propolis alcoholic extract 2% and wax, (6) propolis alcoholic extract 4% and wax, (7) propolis alcoholic extract 6% and wax, (8) propolis alcoholic extract 8% and wax, and (9) propolis alcoholic extract 10% and wax. The fruits were maintained under refrigeration (10 ± 1 ºC and 90 ± 5% relative humidity), being appraised every three days for 15 days and more 3 days of commercialization simulation at room temperature (23± 1 ºC and 18% relative humidity).The evaluation parameters were the weight loss, respiratory activity, pH, firmness, tritable acidity (AT), soluble solids (SS), and ratio. The results of weigth loss, respiratory activity and firmness were the most significant to show the difference among the treatments. ‘Hass’ avocado fruits submitted the application of propolis associated the vegetable wax present smaller weight loss, CO2 production and firmness in relation to the control fruits. The fruits of the treatment with propolis alcoholic extract 2% and wax presented the most promising results. Objetivou-se neste trabalho avaliar a aplicação de própolis e cera vegetal na qualidade pós-colheita do abacate ‘Hass’. Os frutos selecionados foram submetidos aos tratamentos (1) sem cera e sem própolis, (2) com cera vegetal, (3) extrato alcoólico de própolis 100%, (4) cera e etanol 70%, (5) extrato alcoólico de própolis 2% e cera, (6) extrato alcoólico de própolis 4% e cera, (7) extrato alcoólico de própolis 6% e cera, (8) extrato alcoólico de própolis 8% e cera e (9) extrato alcoólico de própolis 10% e cera. Os frutos foram mantidos sob refrigeração (10 ± 1 ºC e 90 ± 5% umidade relativa), sendo avaliados a cada três dias durante 15 dias e mais 3 dias de simulação de comercialização em temperatura ambiente (23± 1 ºC e 18% umidade relativa). Os parâmetros de avaliação foram a perda de massa, atividade respiratória, pH, firmeza, acidez titulável (AT), sólidos solúveis (SS) e ratio. Os resultados de perda de massa, atividade respiratória e firmeza foram os mais significativos para mostrando diferença entre os tratamentos. Frutos de abacate ‘Hass’ submetidos à aplicação de própolis associado a cera vegetal apresentam menor perda massa, produção de CO2 e firmeza em relação aos frutos controle. Os frutos do tratamento com extrato alcoólico de própolis 2% e cera apresentaram os resultados mais promissores.

A capacidade antioxidante e a qualidade pós-colheita do abacate 'Fuerte' foram avaliadas. Os frutos foram mantidos sob temperatura ambiente (24 ± 1 ºC) e sob refrigeração em 10 ± 1 ºC e 90±5% UR e avaliados durante 15 dias. Determinaram-se a perda de massa e a taxa respiratória. As características físico-químicas avaliadas foram acidez total titulável (AT), sólidos solúveis (SS), ratio, pH, firmeza, atividade da enzima polifenoloxidase (PPO), cor (L, a* e b*), fenólicos totais e atividade antioxidante (AA) por DPPH·. Nas duas condições de armazenamento, o pico respiratório ocorreu no 9º dia.Os frutos mantidos sob temperatura refrigerada apresentaram menor perda de massa e maior firmeza em relação àqueles em temperatura ambiente. O comportamento respiratório refletiu na redução dos valores de AT e no conteúdo de SS que diminuíram a partir do pico de respiração. Os valores de pH aumentaram como consequência da diminuição da AT. Os valores de luminosidade mantiveram-se elevados, observando-se diminuição do componente de cor verde na polpa com o armazenamento. A atividade da PPO diminuiu com o armazenamento. Os valores de AA variaram de 17,6 a 68,7%. O conteúdo de fenólicos totais diminuiu após o pico respiratório, e valores crescentes de AA foram observados mesmo após o 9º dia.

The elaboration of avocado products for commercialization keeping their characteristics of fresh product has been limited. The cut avocado darkens quickly and their sensorial characteristics are modified with the storage. In the present research, the sensorial parameters, microbiological stability, and peroxidase and polyphenoloxidase activity were evaluated in guacamole added with ascorbic acid and conserved under low temperature, by using avocado variety Hass. Products were conditioned in polyethylene+nylon packages with and without vacuum application; then, they were subjected to the slow and fast freezing (-18ºC) and stored in freezer (-18ºC). Evaluations were performed at the moment of elaboration of the product (t0) and at 3, 7 and 30 days post-storage. At t30, samples were kept under refrigeration (4 ±1oC) and evaluated at 3, 5 and 7 days. After the 30 days of storage, –18 ºC under freezing, followed by thawing and keeping at 4±1ºC for 7 days, the notes for the sensorial parameters decreased. The peroxidase activity was totally inhibited in the elaborated product and the polifenol oxidase activity considerably decreased in the guacamole (20.07 mM catechol/g fresh matter) relative to those in the fruit (58.31 mM catechol/g fresh matter), however with no significant variation during storage (at -18ºC). The samples were microbiologically stable under the conditions of the present study. The addition of ascorbic acid contributed to the conservation of the frozen avocado product by decreasing the enzymatic activity. However, the sensorial parameters are prejudiced under thawing and storage at 4 ±1oC.A elaboração de produtos de abacate para comercialização mantendo suas características de produto fresco é limitada, já que o fruto cortado escurece rapidamente e suas características sensoriais são modificadas com o armazenamento. Na presente pesquisa, avaliaram-se os parâmetros sensoriais, estabilidade microbiológica e atividade de peroxidase (POD, EC 1.11.1.7) e polifenoloxidase (PPO, EC 1.10.3.1) do guacamole adicionado de ácido ascórbico e conservado sob frio elaborado, usando-se abacate da variedade Hass. Produtos acondicionados em embalagens de polietileno+nylon com e sem aplicação de vácuo foram submetidos ao congelamento lento e rápido (-18ºC) e armazenados em freezer (-18ºC). Avaliações foram realizadas no momento da elaboração do produto (t0) e aos 3, 7 e 30 dias após armazenamento, sendo que no t30 as amostras foram mantidas sob refrigeração (4 ±1ºC) e avaliadas após 3, 5 e 7 dias. Após 30 dias de armazenamento, a - 18ºC sob congelamento, seguido de descongelamento e mantendo-se à 4ºC±1 por 7 dias, as notas para os parâmetros sensoriais diminuram. A peroxidase foi totalmente inibida no produto elaborado e a atividade da enzima polifenoloxidase diminuiu consideravelmente no guacamole (20,07 mM de catecol/g massa fresca) em relação ao fruto (58,31 mM de catecol/g massa fresca), porém sem variação significativa durante o armazenamento (à -18ºC). As amostras apresentaram-se microbiologicamente estáveis nas condições do estudo. A adição de acido ascórbico contribuiu para conservação do produto de abacate congelado diminuindo a atividade enzimática. No entanto, os parâmetros sensoriais são prejudicados com o descongelamento e armazenamento à 4±1oC.

Se estudió la variación estacional de la fotosíntesis y parámetros fisiológicos relacionados con ésta en los cultivares de aguacate Colín V-101 y Rincón (ambos de bajo porte) y Hass en el clima Semicálido subhúmedo del Valle de Matatipac, Nayarit. Se midió la fotosíntesis en seis fechas de muestreo y en cada una de ellas fueron evaluadas cinco hojas maduras en cada uno de cinco árboles por cultivar. La primera medición se hizo al fin de verano (21 Sep. 2002), dos lecturas en otoño (20 Oct. y 20 Nov. 2002), dos en invierno (22 Ene. y 23 Feb. 2003) y una al inicio de la primavera (30 Mar. 2003). La dispersión estacional de la tasa de fotosíntesis neta (A) de los tres cultivares de aguacate siguió el mismo patrón de distribución a través de las estaciones del año. La tasa de A al fin de verano fue baja (18.45 mmol CO2 m-2 s-1), se elevó ligeramente (20.22 mmol CO2 m-2 s-1) al inicio de otoño, y alcanzó el promedio máximo en pleno otoño con 30.05 mmol CO2 m-2 s-1 que coincidió con el crecimiento de fruto. A se estabilizó (29.84 mmol CO2 m-2 s-1) durante el invierno y descendió significativamente al inicio de primavera (17.61 mmol CO2 m-2 s-1). La tasa de A resultó afectada por las condiciones climatológicas de cada estación y el estado fenológico de los cultivares de aguacate.

From a hexane extract of avocado pulp (Persea americana Mill.), an 1:3 mixture of 2-(heptadec-16-enyl)- and 2-(heptadec-16-ynyl)-4-hydroxy -tetrahydrofurans was characterized by NMR techniques. These compounds have not been previously reported from natural sources.

Avocados possess high nutritional value with proven effectiveness in preventing cardiovascular diseases, attributed primarily to their unsaturated fatty acids content. This fruit is also rich in carotenoids and vitamins, particularly vitamin E. This work evaluates the antioxidant capacity and total phenolic content of hydrothermally-treated Fuerte avocado. Fruits were selected and hydrothermally treated at 45oC for 5, 10, 15 and 20 min. They were then stored in a refrigerator (10 ± 1oC and 90±5% relative humidity) and evaluated over a 15-day period. The total phenolic content increased up to the sixth day of storage, and decreased thereafter, without differences between the treatments. The percentage of antioxidant capacity of the control and the hydrothermally-treated samples for 5 and 10 min increased during storage. Untreated fruits showed the highest percentage of antioxidant capacity. However, the antioxidant capacity of avocado fruits subjected to these treatments declined starting on the twelfth day of storage, possibly due to the fruits’ senescence. Hydrothermal treatments for 15 and 20 min delayed fruit senescence while the antioxidant capacity continued to increase up to the fifteenth day of storage. No significant correlation was found between antioxidant capacity and total phenolic content. The antioxidant capacity of ripe Fuerte avocado was higher than that of unripe or overripe avocado.

Highlights: [•] Avocado composition studied with respect to nutrient stability compared over time. [•] Preharvest conditions and storage differently influenced bioactive compounds. [•] Dry matter increased with maturity regardless of growing area. [•] Oleic acid content could be used to distinguish between avocado fruit growing areas. [•] C7 sugars content was negatively correlated with mesocarp ripening. [Copyright &y& Elsevier]

Abstract: Ethnopharmacological relevance: The leaves of Persea americana Mill. (Lauraceae) have been popularly used in the treatment of diabetes in countries in Latin America and Africa. Aim of the study: To investigate the hypoglycaemic properties and to determine the molecular mechanism by which the hydroalcoholic extract of the leaves of Persea americana reduce blood glucose levels in streptozotocin (STZ)-induced diabetes in rats via the enzymatic pathway of protein kinase B (PKB/Akt). Methods: The hydroalcoholic extract of the leaves of Persea americana (0.15 and 0.3g/kg/day), vehicle and metformin (0.5g/kg/day) were administered orally to STZ-diabetic rats (n =7/group) for 4 weeks. Changes in body weight, food and water intake, fasting glucose levels and oral glucose tolerance were evaluated. Phosphorylation and the expression of PKB in the liver and soleus muscle were determined by Western blot. Results: The hydroalcoholic extract of the leaves of Persea americana reduced blood glucose levels and improved the metabolic state of the animals. Additionally, PKB activation was observed in the liver and skeletal muscle of treated rats when compared with untreated rats. Conclusion: The results indicate that the hydroalcoholic extract of the leaves of Persea americana has anti-diabetic properties and possibly acts to regulate glucose uptake in liver and muscles by way of PKB/Akt activation, restoring the intracellular energy balance. [Copyright &y& Elsevier]

Abstract: Despite problems of low fruit set, small fruit size and alternate bearing, the Hass cultivar dominates commercial avocado production worldwide. To increase yield and fruit size, gibberellic acid (GA3) (25mgL−1) was applied at different stages of ‘Hass’ avocado tree phenology: (i) mid–late April (flower abscission), end of June–beginning of July (fruit abscission and beginning of the exponential phase of fruit growth), and mid-January (beginning of pre-harvest fruit drop); (ii) end of June–beginning of July; and (iii) mid-September (near the end of the major fruit abscission period; period of exponential fruit growth). In both years of the research, applications of GA3 in April and June–July were within the periods of intense flower and fruit abscission, respectively; fruit abscission was low in September and January. Maximum air temperature was not related to flower or fruit abscission. In the on-crop year (391 fruit per untreated control tree), a single application of GA3 at the end of June–beginning of July significantly increased total yield (kilograms only) and yield of commercially valuable fruit (178–325g/fruit) (as kilograms and number per tree) compared with the control (P <0.0001). GA3 applied in September increased total yield (kilograms only) and yield of commercially valuable fruit (kilograms and number per tree) to values intermediate to and not significantly different from all other treatments, except trees receiving multiple applications of GA3. This treatment reduced total yield and yield of commercially valuable fruit (kilograms and number per tree) relative to all treatments (P ≤0.0002). In contrast, during the off-crop year (32 fruit per control tree), no GA3 treatment had a significant effect on yield or fruit size compared with the control and all other GA3 treatments. For ‘Hass’ avocado, there was no negative effect from applying GA3 at the end of June–beginning of July in both the off- and on-crop years; 2-year cumulative total yield and yield of commercially valuable fruit were increased by 27kg (128 fruit) and 22kg (101 fruit) per tree, respectively, above the yield of untreated control trees (P <0.0001). [Copyright &y& Elsevier]

Avocado propagation is commercialy realized by grafting of the desirable variety in seminal rootstocks. However, the literature is discordant about the occurrence of poliembriony and type of fruit of this specie. In function of this, as research had the objective to characterize the type of fruit, seed morphological aspects and the seedling nurse, besides to evaluate the number of embryos existent. The avocado fruit is a berry. The seeds are monoembryonics and exalbuminous. The germination is hipogeal and the emergene of the seedling occurred 33 days after sowing. The primary root is long and white and the secondary roots are short and filiforns. The cotyledons are massive and pinkish. It was possible to observe the presence of multi-stem in avocado seed, originated from the collar. The seeds present multi-stems; the beginning of seedling emergence stabilization occurred in the eighth week, being unviable for propagation of this species to keep these seeds in the nursery for more time. [ABSTRACT FROM AUTHOR]

Abstract: An efficient protocol for in vitro maturation of very immature, <10mm, avocado embryos has been developed. The efficiency of plant recovery as well as the quality of the resulting plants was greatly improved by including a maturation phase prior to induction of germination. The influence of different factors, such as the gelling agent, organic supplements or abscisic acid, on embryo maturation and subsequent germination was tested. Optimum conditions were met when maturation was carried out in B5m medium supplemented with the Jensen''s amino acids, an extra 88mM sucrose and 6gl−1 agar as gelling agent. At these conditions, embryos which had been collected 68 days after pollination germinated at a 65% rate in solid medium, giving rise to healthy and vigorous plantlets. Anatomical differentiation and storage product accumulation occurring during the in vitro maturation phase were studied by means of histological techniques. Results obtained revealed that, at the end of the in vitro maturation period, embryos resembled the pattern previously established for avocado embryos matured under in vivo conditions: histodifferentiation had been accomplished and starch granules and protein bodies were abundant. [Copyright &y& Elsevier]

Abstract: A common irrigation-scheduling problem in orchards is the proper location of instruments for monitoring soil water content within the active root zone. Given the high spatial variability of soils in the field, and seasonal changes in root distribution and frequency, both within the orchard and around the trees, the accuracy and representativeness of soil water measurements can be strongly affected. Adequate soil water monitoring in orchards thus requires assessment of the variability and location of the active roots in a given location over an extended period of time. We examined the root systems of 12-year-old ‘Hass’ avocado (Persea americana Mill.) trees grafted on ‘Mexicola’ seedling rootstocks, growing in fine or coarse-textured soils, under either drip or microsprinkler irrigation systems in Central Chile. We dug 3m long and 0.75m deep trenches within the tree rows in spring, summer and autumn, and counted the active roots (white, diameter ≤2mm) found on the walls. Over the three growing seasons of our study, season had the most significant effect on root distribution, as autumn root frequencies accounted for about half of the cumulative average. Also, the location of the highest concentration of roots under microsprinklers in autumn clearly differed between the fine soils, at about 200cm from the trunk and 50–60cm deep, and coarse soils, where they were found within 30cm from the trunk, and within the first 25cm of soil. Trees in fine soil had 25% more roots than those in coarse soil, and drip irrigation produced about 30% more roots than microsprinkler, although both of these figures are mainly due to the high number of roots found in the fine soil-drip irrigation combination. Overall, we found the highest root frequency within the first meter from the tree trunk, for all combinations, with some differences between irrigation types. Throughout the growing season in semi-arid regions, some changes in both the quantity of tree roots and the location of the zones of the greatest root activity should be expected, which will vary according to the seasonal soil temperatures, soil texture, and type of irrigation used. [Copyright &y& Elsevier]

Abstract: The effect of peptone on in vitro regeneration of avocado''s shoots and roots from juvenile or mature stem sections was studied. In this study, both mature and juvenile explants were used to study the effect of peptone on shoot regeneration. Explants were necrotized on Murashige and Skoog (MS) medium without or with plant growth regulators. On the MS medium supplemented with both peptone and benzyladenine or dichlorophenoxyacetic acid, explants survived but significantly delayed in shoot regeneration. Addition of peptone alone into the medium with an optimal amount of 2.0% (w/v) induced shoot formation. Shoot formation also occurred in nodal sections from mature plant but the regeneration rate remained low. All juvenile explant-derived shoots formed root on the medium supplemented with peptone and naphthaleneacetic acid. [Copyright &y& Elsevier]

A tissue analysis trial for the diagnosis of boron status was performed during the 2003 growing season in Paine County, Metropolitan Region, Chile. Five-year-old 'Hass' avocado (Persea americana Mill.) trees were soil treated with borax [11% boron (B)] applied to the soil surface at rates of 0, 75, 150, or 300 g/tree, each with three replicates. Borax was incorporated into the soil approximately two and half months after flower anthesis, applying half of the dose on each side of the tree along the closest irrigation furrow. Thirty spring flush leaves and 15 fruits with peduncle were collected per tree 4 months after application. Boron concentration in leaf, fruit peduncle, and fruit pulp was determined by spectrocolorimetry. Differences among treatments were better detected in peduncle and pulp samples than in leaf samples. The relationships between borax dose and B concentration in the tissue were R2 = 0.77, 0.75, and 0.53 in peduncle, pulp, and leaf, respectively. Consequently, peduncle and pulp appear as promising tissues, probably better than leaf, for diagnosing the boron status of avocado trees. [ABSTRACT FROM AUTHOR]

Abstract: An in vitro culture protocol was developed as a means of avocado embryo rescue. Different factors including presence of cotyledons, medium texture and cold or gibberellic acid pretreatments, were studied. To better understand the germination process in this recalcitrant species, immature zygotic embryos at different stages were used in these experiments. Optimum results were dependant on the embryo developmental stage. Whereas smaller embryos (5mm long) germinated better in M1 liquid medium, 15mm long embryos responded better when precultured in B5m medium supplemented with 1mgl−1 GA3, and fully mature embryos were capable of germinating directly in solid M1 medium. Our results suggest the existence of two types of dormancy in avocado embryos: an embryo-dormancy caused by cotyledons, and another type of dormancy, mainly occurring in 35mm long embryos and revealed by the formation of dwarfing rosette seedlings, that can be released by a GA3 pretreatment. [Copyright &y& Elsevier]

Abstract: The kinetics of acetaldehyde (AA) and ethanol (EtOH) accumulation and pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities were studied in pre-climacteric ‘Hass’ avocado fruit flesh during induction and recovery from hypoxic conditions at 6°C. Oxygen levels <0.5% resulted in a rapid accumulation of AA and EtOH. The pattern of AA and EtOH accumulation could be described by a hyperbolic model, although the initial 96h of EtOH accumulation was linear. The accumulation of EtOH and AA was coincident with a doubling of the extractable ADH and PDC activities after 120h exposure. Exposure of the fruit to up to 20% CO2 concentrations resulted in an increase in tissue levels of AA, but not EtOH. The pattern of AA accumulation under high CO2 was similar to that under low O2, with the level of AA being higher at higher CO2 concentrations. The AA and EtOH induced by low O2 declined to basal levels in an exponential manner when O2 was increased from ≤0.5 to ≥2%. The longer the duration of hypoxic induction, the longer the time required for AA and EtOH to decline to basal levels. When low O2 induction was 48h or less, the time required for AA and EtOH to decline to basal levels was not affected by O2 concentrations >2%. However, after 96h induction, the initial rate of decline in AA or EtOH was slower at lower O2 concentrations. Including 20% CO2 in the recovery atmosphere decreased the initial rapid rate of AA and EtOH decline, affecting EtOH levels more than AA, although both compounds reached pre-induction levels at approximately the same time. The rate of decline of ADH and PDC activity following low O2 induction was accelerated by the presence of CO2 in the atmosphere. Based on the rapid induction of AA and EtOH in response to low O2 stress, and the comparable rapid recovery to basal levels after removal of the stress atmosphere, together with a seemingly high tolerance to O2 atmospheres <2% and the similar but relatively smaller effect of CO2 compared with O2, it is concluded that preclimacteric ‘Hass’ avocados are physiologically well suited to dynamic CA storage. [Copyright &y& Elsevier]

In order to determine the effect of iron chlorosis on fruit size and oil content of avocado (Persea americana Mill.), a trial was conducted on a 22-year-old orchard cv. Hass located at Quillota, Chile (32°51′ S lat., 71°6′ W long.). Twelve trees with different degrees of iron chlorosis were selected, some with normal green foliage and others highly chlorotic. Fifteen fruit and 30 leaves per tree were taken on August 30. In this samples iron concentration was determined by spectrophotometry. Color by tri-stimulus colorimetry and chlorophyll concentration by ethanol extraction and spectrophotometer absorbance were measured on leaves and fruit peels. Fruit weight and oil content were measured by petroleum ether extraction. Fruit from normal trees had an iron concentration of 13.8 mg kg-1 (P ≤ 0,05) higher than that of chlorotic trees. A high correlation between the chlorophyll level of leaves and fruit peels was found (R² = 0.74). The leaf chlorophyll concentration was also highly associated with the fruit weight (R² = 0.93) and oil content (R² = 0.68).A similar relation was found between the fruit peel chlorophyll concentration and the fruit weight (R² = 0.70) and its oil content (R² = 0.86). It is concluded that iron chlorosis diminished fruit size and oil concentration in avocados. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the anaerobic compensation point (ACP) in ‘Hass’ avocado fruits as a function of temperature and the advance in ripening. Controlled atmosphere treatments with oxygen in a range from 0 to 4%, with two temperature levels, 5.5 and 20°C, applied to fruits of three firmness levels which included the pre-climacteric, the mid-zone of the climacteric rise and the post-climacteric phase. Mean ACP values of 144% and 1.81% were found for 5.5°C and 20°C, respectively. These values increased with ripening. The production of fermentative metabolites was not exclusive of O2 concentrations below to ACP, and temperature affected the accumulation of these compounds, with values of 10.7 μmol/100mL at 5.5°C and 101.3 μmol/100mL at 20°C. The production of those metabolites significantly increased with ripening and the values were, in the post-climacteric stage, 20 and 39 times greater than in the pre-climacteric one, at 5.5°C and 20°C, respectively. Results obtained here could be used to define adequate storage conditions for ‘Hass’ avocado fruits in modified atmosphere systems. [ABSTRACT FROM AUTHOR]

Pretreatments at moderate temperatures applied immediately prior to the high or low temperature treatments can reduce skin damage to avocados. These temperature tolerance-inducing pretreatments have generally been applied immediately prior to the high or low temperature. We examined whether a delay between the pretreatment and potentially damaging high and low temperatures may cause a loss in the induced tolerance. A hot air pretreatment (38 °C for 6 h) applied prior to storage at 0 °C for 3 weeks with intervening delays of 1–4 days at 20 °C, showed a large reduction in chilling injury as a result of the pretreatment but that this was progressively lost with increasing delay to storage. Hot water pretreatments (38 °C for 0, 5, 20 and 60 min) increasingly reduced chilling damage at 0 °C, and heat damage from a hot water treatment (HWT) at 50 °C/10 min. With delays of up to 3–24 h prior to the HWT, heat damage was reduced for the 5 and 20 min pretreatments. However, delays up to 5 days between pretreatment and HWT, loss of heat tolerance was observed. For delays of between 1 and 5 days there was a clear loss of chilling tolerance which was more rapid than the increase in chilling injury in control treatments for the same delays. However, the effect of delays <24 h was less clear for the 5 and 20 min treatments. Heat shock protein (hsp) 17 and 70 homologous RNA levels were induced by heat pretreatments and delays lead to first an increase in RNA levels (maximum induction at 6 h), which paralleled the induced tolerance, and then a decline which was less closely associated with loss in tolerance. Thus, delayed time between thermotolerance inducing pretreatments and high or low temperatures can lead to a general reduction in tolerance, and should be considered and exploited in the application of temperature treatments. A dose response/decay model for induced tolerance fits the pattern of temperature damage and hsp expression. [Copyright &y& Elsevier]

The effect of mineral salts, sucrose, gellan gum, abscisic acid and coconut water on maturation of avocado (Persea americana Mill.) somatic embryos was studied. Use of B5 major salts was essential to obtain white-opaque embryos. Sucrose at 175 mM, gellan gum (6.8 g l-1) or coconut water (10–20%) also enhanced the recovery of white-opaque embryos. Abscisic acid slightly enhanced the appearance of white-opaque embryos. White-opaque embryos were further grown on MS, modified B5 medium supplemented with 10% coconut water or Jensen–MS media and they subsequently germinated on M1 medium. Higher germination rates (11.11%) were obtained with embryos that matured on modified B5 medium supplemented with 10% coconut water, although larger embryos developed on MS medium. Thus, embryo size during maturation does not seem to be correlated with germination capacity. Shoots obtained from germinated embryos could be multiplied in the presence of 4.44 μM benzylaminopurine and successfully rooted (80% rate) after a 3 days treatment with 4.92 μM indole-3-butyric acid. Over 90% of the rooted shoots survived acclimatization. [Copyright &y& Elsevier]

The effect of lowering O2 concentration on chlorophyll fluorescence was continuously monitored in apple (Malus x domestica Borkh.), pear (Pyrus communis L.), banana (Musa L. Cavendish subgroup), kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson), mango (Mangifera indica L.), and avocado (Persea americana Mill.) fruit, using a large surface-area sensor. In all of the six fruit, there were specific O2 concentrations at which the Fo and Fv/Fm chlorophyll fluorescence values suddenly increased and decreased, respectively. When the O2 concentrations were increased, the Fo and Fv/Fm signals returned to their previous values. Since the O2 concentrations at which this phenomenon occurred were close to known low O2 thresholds for these fruit, it may be that chlorophyll fluorescence can rapidly and non- destructively determine the lowest acceptable O2 concentration for stored chlorophyll-containing plant products. [Copyright &y& Elsevier]

The expression of specific cellulase (endo-1,4-β-glucanase; EC 3.2.1.4) gene family members was monitored in the mesocarp and abscission zone of mature avocado fruit. Fruit abscission was induced by either girdling of the stem or treatment with 2-chloroethyl phosphonic acid (CEPA). Gene-specific probes that hybridized to the 3' untranslated region of either the cel1 or the cel2 gene of avocado were used to distinguish between RNA transcripts from these two closely related genes. Only cel1 transcripts were detected in ripe mesocarp. An accumulation of cel1 mRNA has been observed in the activated fruit abscission zone. Using antibody raised against cellulase protein isolated from ripe fruit, a cross-reacting cellulase antigen was detected in extracts from the abscission zones of CEPA-treated and girdled fruit. Cellulase enzyme activity was detected in these tissues. These results suggest that the same cellulase gene (cel1) that has been shown to be expressed in the mesocarp during fruit ripening might also be involved in the mature fruit abscission process. [ABSTRACT FROM AUTHOR]

Avocado oil is prized for its high nutritional value due to the substantial amounts of triglycerides (TGs) and unsaturated fatty acids (FAs) present. While avocado oil is traditionally extracted from mature fruit flesh, alternative sources such as avocado seed oil have recently increased in popularity. Unfortunately, sufficient evidence is not available to support the claimed health benefit and safe use of such oils. To address potential quality issues and identify possible adulteration, authenticated avocado oils extracted from the fruit peel, pulp and seed by supercritical fluid extraction (SFE), as well as commercial avocado pulp and seed oils sold in US market were analyzed for TGs and FAs in the present study. Characterization and quantification of TGs were conducted using UHPLC/ESI-MS. Thirteen TGs containing saturated and unsaturated fatty acids in avocado oils were unambiguously identified. Compared to traditional analytical methods, which are based only on the relative areas of chromatographic peaks neglecting the differences in the relative response of individual TG, our method improved the quantification of TGs by using the reference standards whenever possible or the reference standards with the same equivalent carbon number (ECN). To verify the precision and accuracy of the UHPLC/ESI-MS method, the hydrolysis and transesterification products of avocado oil were analyzed for fatty acid methyl esters using a GC/MS method. The concentrations of individual FA were calculated, and the results agreed with the UHPLC/ESI-MS method. Although chemical profiles of avocado oils from pulp and peel are very similar, a significant difference was observed for the seed oil. Principal component analysis (PCA) based on TG and FA compositional data allowed correct identification of individual avocado oil and detection of possible adulteration. [ABSTRACT FROM AUTHOR]

The research objective was to characterize avocado's aroma-active volatiles and use information about its overall composition, such as lipid profile, to discuss likely biosynthetic origins. To achieve this, two varieties, "Hass" and "3-29-5" (GEM), were evaluated during their commercial harvest period for dry weight, moisture content (freeze-drying), oil content (Soxhlet extraction), fatty acid composition, and aroma profile. Solvent-assisted flavor evaporation and aroma extract dilution analysis were performed on aroma extracts. Oleic acid (>50%) was the prominent fatty acid in the oil of both varieties. The majority of the aroma-active compounds in avocado are lipid-derived. The most notable compounds are 1-octen-3-one (mushroom) with a flavor dilution factor as high as 8192, hexanal (grassy), ( Z )-4-decenal, an unknown, and ( E,E )-2,4-nonadienal. Over the mid-to-late harvest season, a decline in hexanal and an increase in octanal were observed. In contrast to "Hass", the hexanal content was relatively stable in "3-29-5".

Persea americana Mill, cv. Hass, also known as avocado, has been reported to possess hypolipidemic, anti-diabetic, anti-oxidant, cardioprotective, and photoprotective potencies. However, few studies have reported its anti-colitic effects. In this study, we investigated anti-colitic effects of ethanol extract of P. americana (EEP) in dextran sulfate sodium (DSS)-induced colitic mice and the involved molecular mechanisms. EEP effectively improved clinical signs and histological characteristics of DSS-induced colitis mice. In DSS-exposed colonic tissues, EEP reduced expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and pro-inflammatory cytokines such as interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α. Moreover, EEP suppressed DSS-induced activation of nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3). Consistent with in vivo results, EEP also suppressed protein and mRNA expression levels of iNOS, COX-2, and pro-inflammatory cytokines via NF-κB and STAT3 inactivation in LPS-induced RAW 264.7 macrophages. Taken together, our data indicate that ethanol extract of avocado may be used as a promising therapeutic against inflammatory bowel diseases by suppressing the NF-κB and STAT3 signaling pathway. [ABSTRACT FROM AUTHOR]

ABSTRACT It was evaluated the possibility to produce two seedlings per avocado seed, through the separation of cotyledons. Two seed lots from two different ungrafted trees were evaluated. From the first tree were obtained 60 seeds, and 50 from the second. Half the seeds of each lot had their cotyledons separated and then whole seeds and half-seeds were sown in river sand. At 90 days after sowing, percentage of germinated seeds, shoot height, main root length, fresh and dry mass of shoots, roots and cotyledons were evaluated. From the first lot of seeds, there was 100% germination, both for the whole seeds and for the half-seeds. For all traits evaluated, higher mean values were observed for seedlings formed from whole seeds. In the second lot of seeds, 88% of germination was observed for whole seeds and 82% of germination for half-seeds. In this second lot, there were no significant differences between the seedlings formed from whole seeds and half-seeds for any of the characteristics evaluated, except for fresh and dry mass of cotyledons. Thus, it is possible to produce two seedlings or rootstocks with a single avocado seed, although this may slightly delay the development of the seedlings