Soluble Solids Content Values Research Articles

Microbial and enzymatic stability of fruit juice-milk beverages treated by high intensity pulsed electric fields or heat during refrigerated storage

The influence of high intensity pulsed electric fields (HIPEF) treatment (35 kV/cm, bipolar 4 μs square wave pulses at 200 Hz) on the inactivation of Listeria innocua in fruit juice–whole (FJ–WM) or skim milk (FJ–SM) beverages was assessed. As well, the effects of HIPEF or conventional thermal (90 °C 60 s) processing in terms of microbial and enzymatic stability and changes on physicochemical parameters of the beverages during refrigerated storage were also studied. HIPEF and thermal processing ensured the microbial stability of the beverages during 56 days at 4 °C without significant changes on pH, acidity and soluble solid content values. Thermal processing was more effective than HIPEF in reducing Pectin Methyl Esterase (PME) activity in FJ–SM and FJ–WM beverages since its activity was reduced by 70.66% and 87.33%, respectively. With regards to Polygalacturonase (PG), HIPEF treatment reduced by 26.92% and 20.93% the enzyme activity in the FJ–WM and FJ–SM beverages, respectively, whereas thermal treatment did not inactivate PG in both beverages. HIPEF or thermally-treated samples showed higher viscosity than the untreated ones, being this increment more pronounced in the beverages with whole milk. Therefore, HIPEF processing may be a feasible technology in order to obtain shelf stable and fresh-like fruit juice-milk beverages.

Quality analysis of ‘Redhaven’ peach fruit grafted on 11 rootstocks of different genetic origin in a replant soil

The fruit quality of ‘Redhaven’ peach [ Prunus persica (L.) Basch.] grafted on 11 (Adesoto, Julior, GF 677, Monegro, Barrier 1, Cadaman, MrS 2/5, Ishtara, Penta, Tetra and peach seedling) experimental rootstocks was evaluated in 2008 under replant orchard conditions. Several quality indices [weight, flesh firmness (FF), ground colour measurements, and soluble solids content (SSC)] were measured, and HPLC analysis were performed for numerous chemical parameters (quantification of individual sugars, organic acids, phenolic compounds in skin and in pulp). Total phenolic content and antioxidant capacity in skin and in pulp were also measured. Julior had the heaviest fruit, while Barrier 1 and GF 677 produced fruit lighter in weight. Rootstocks influenced harvest maturity. Monegro produced the least ripe fruit, characterised by high FF, phenolic compounds in the skin and low SSC. Adesoto rootstock resulted in the best overall fruit quality (high values of SSC, individual and total sugar content levels, individual and total organic acids and phenolic compounds in pulp) as well as high total yield. Julior rootstock also produced good quality peach (high values of SSC, individual and total sugars). Cadaman and peach seedling rootstock produced ‘Redhaven’ fruit of the lowest quality, indicated by low values of sugars, organic acids, phenolic compounds in pulp and in skin.

Fenologia e produção de cultivares americanas e híbridas de uvas para vinho, em Jundiai-SP

O comportamento fenológico e produtivo das cultivares de uvas rústicas para vinho 'Moscatel de Jundiaí', 'Máximo', 'Madalena', 'Seibel 10096', 'Isabel' e 'Niagara Rosada' foi avaliado em vinhedo localizado em Jundiaí (SP), durante os anos agrícolas de 2000/01 a 2002/03. As videiras foram enxertadas em 'IAC 766' e conduzidas em espaldeira, com poda curta de inverno. O delineamento experimental foi o inteiramente casualizado, com parcelas de três plantas e cinco repetições. Foram realizadas avaliações fenológicas semanais a partir da data de poda e, na época da colheita, determinaram-se as variáveis: produção por planta; número e massa dos cachos, e teor de sólidos solúveis. As cultivares 'Seibel 10096', 'Moscatel de Jundiaí', 'Madalena' e 'Máximo' mostraram-se mais tardias com ciclo de 149 dias em comparação à 'Niagara Rosada', que foi a mais precoce, com ciclo de 135 dias. 'Máximo' e 'Seibel 10096' apresentaram produção de, respectivamente, 4,28 e 4,41 kg.planta-1, diferindo de 'Madalena' e 'Isabel', com 3,09 e 2,50 kg.planta-1. Para 'Moscatel de Jundiaí' e 'Niagara Rosada', foram obtidas produções intermediárias entre 3,0 e 3,5 kg.planta-1. Para 'Seibel 10096', foi obtido o maior valor de massa do cacho (283,6g), enquanto, para 'Isabel' (96,5g) e 'Madalena' (139,6g), foram obtidos os menores valores. Os maiores valores de teor de sólidos solúveis, acima de 17,0º Brix, foram obtidos na 'Moscatel de Jundiaí', 'Máximo' e 'Seibel 10096', enquanto 'Isabel' e 'Niagara Rosada' apresentaram valores inferiores a 15,9º Brix. Dentre as cultivares avaliadas, podem constituir-se em opção para o viticultor a 'Máximo' e a 'Seibel 10096' para vinhos tintos, e 'Moscatel de Jundiaí', para brancos.

Produtividade e qualidade pós-colheita de cultivares de cebola em sistemas de cultivo orgânico e convencional

O trabalho teve como objetivo avaliar a produtividade, características físico-químicas e perdas pós-colheita de cultivares de cebola produzidas em sistemas de cultivo convencional e orgânico. Foram avaliadas a produção total e a massa média dos bulbos, o teor de sólidos solúveis, a acidez titulável, a massa seca e o pH. Além destas características, foram avaliadas perdas pós-colheita, com observação da perda de massa. Os bulbos foram armazenados em câmara fria à temperatura de 3ºC ± 1ºC e umidade relativa de 75% ± 5% durante 90 dias. O sistema orgânico foi superior ao convencional em produtividade, não diferindo significativamente nas demais características. A produtividade do híbrido Baia F1 foi mais expressiva, nos dois sistemas de cultivo, assim como as maiores massas médias de bulbos. Dentre as cultivares, a Red Creole proporcionou elevados valores de sólidos solúveis e massa seca de bulbos, nos dois sistemas de cultivo. Essas características indicam que a cultivar Red Creole possui bom desempenho para industrialização. Nas avaliações pós-colheita, na cultivar Red Creole observou-se a maior redução na massa de bulbos, tanto no sistema orgânico quanto no convencional. Estes dados revelam que não existe influência do sistema de cultivo na conservação pós-colheita dos bulbos.

The Measurement of Soluble Solids Content in Snake Fruit (Salacca Edulis Reinw) cv. Pondoh Using A Portable Spectrometer

In this research we reported the use of near infrared spectroscopy for nondestructive soluble solids content (SSC) measurement in intact snake fruit (Salacca edulis Reinw) cv. Pondoh. The spectra of 100 samples were acquired in the range of 300-1040 nm using an available, low cost portable spectrometer (VISNIR USB4000). The spectrometer used an array of linear CCD as a detector. The LS-1 Tungsten Halogen lamp is used as light source. This system is also equipped with a fiber optic. Snake fruits were placed on the sample holder and the spectra were measured using 100 ms of integration time and 50 scans for averaging. The spectra were acquired in two different positions in the middle of fruit. The total scanning time was 10 s for each fruit. The SSC of snake fruits were measured destructively following the spectra measurement using a digital refractometer. A portion of snake fruit flesh with associated with the point of spectra measurement was cut and juiced. Then the juice of snake fruit was placed on a digital refractometer. The SSC was quantified in Brix value. The trial free version of The Unscrambler V.9.1 was used as chemometrics tools to extract the useful information from the spectra. The calibration model was developed using Partial Least Squares Regression 1 (PLSR1) for three types of spectra, original, smoothing and second derivative spectra. The calibration model was evaluated using some parameters such as coefficient of determination (R2), standard error of prediction (SEP), bias between actual and predicted SSC value and ratio prediction to deviation (RPD) parameter. The possibility of using near infrared spectroscopy to measure SSC of intact snake fruit nondestructively was successfully demonstrated. The best calibration model with 3.32 of RPD value could be obtained.

THE INFLUENCE OF HARVEST TIME ON STRAWBERRY FRUIT QUALITY (FRAGARIA × ANANASSA DUCH.)

The work presents the influence of harvest time on important parameters of fruit quality (fruit weight, chemical composition as well as organoleptic properties) of seven strawberry cultivars ('Cacanska rana', 'Evita', 'Madeleine', 'Eris', 'Selena', 'Cortina' and 'Favette'). The obtained results of fruit weight indicate that the average values are in the range from 8.06 g ('Cacanska rana') to 19.86 g ('Selena'). With regard to chemical fruit composition, higher values of soluble solids content were obtained in the third and fourth harvest in most of cultivars studied. Later harvest time also had a positive influence on decrease of total acids content. Based on most of parameters evaluated it can be concluded that fruit quality of the studied strawberry cultivars expressed different behavior depending on the harvest time.

Visible/Near-Infrared Spectra for Linear and Nonlinear Calibrations: A Case to Predict Soluble Solids Contents and pH Value in Peach

Two sensitive wavelength (SWs) selection methods combined with visible/near-infrared (Vis/NIR) spectroscopy were investigated to determine the soluble solids content (SSC) and pH value in peaches, including latent variables analysis (LVA) and independent component analysis (ICA). A total of 100 samples were prepared for the calibration (n = 70) and prediction (n = 30) sets. Calibration models using SWs selected by LVA and ICA were developed, including linear regression of partial least squares (PLS) analysis and nonlinear regression of least squares-support vector machine (LS-SVM). In the nonlinear models, four SWs selected by ICA achieved the optimal ICA-LS-SVM model compared with LV-LS-SVM and both of them better than linear model of PLS. The correlation coefficients (rp and rcv), root mean square error of cross validation, root mean square error of prediction, and bias by ICA-LS-SVM were 0.9537, 0.9485, 0.4231, 0.4155, and 0.0167 for SSC and 0.9638, 0.9657, 0.0472, 0.0497, and −0.0082 for pH value, respectively. The overall results indicated that ICA was a powerful way for the selection of SWs, and Vis/NIR spectroscopy incorporated to ICA-LS-SVM was successful for the accurate determination of SSC and pH value in peach.

Comparison of calibrations for the determination of soluble solids content and pH of rice vinegars using visible and short-wave near infrared spectroscopy

Visible and short-wave near infrared (Vis/SWNIR) spectroscopy combined with chemometrics was investigated for the fast determination of soluble solids content (SSC) and pH values of rice vinegars. Two hundred and twenty-five samples (45 for each variety) were selected randomly for the calibration set, whereas, 75 samples (15 for each variety) for the validation set, and the remaining 25 samples for the independent set. After some preprocessing, partial least squares (PLS) analysis was implemented for calibration models with different wavelength bands including visible, SWNIR and Vis/SWNIR regions. The best PLS models were achieved with Vis/SWNIR (550–1000 nm) region. Furthermore, different latent variables (5, 6, 7, 8 LVs) were used as inputs of least squares-support vector machine (LS-SVM) to develop the LV-LS-SVM models with grid search technique and RBF kernel. The optimal models were obtained with 6 LVs and they outperformed PLS models. Moreover, effective wavelengths (EWs) were selected according to regression coefficients. The EW-LS-SVM models were developed and an excellent prediction precision was achieved, and the effectiveness of the EWs was also validated. The correlation coefficient ( r), root mean square error of prediction (RMSEP) and bias for the best prediction by EW-LS-SVM were 0.999, 0.189 and 0.051 for SSC, whereas 0.999, 0.008 and −1.7 × 10 −3 for pH, respectively. The overall results indicated that Vis/SWNIR spectroscopy combined with LS-SVM could be applied as a high precision and fast way for the determination of SSC and pH values of rice vinegars.

Measurement of soluble solids content in watermelon by Vis/NIR diffuse transmittance technique

Watermelon is a popular fruit in the world with soluble solids content (SSC) being one of the major characteristics used for assessing its quality. This study was aimed at obtaining a method for nondestructive SSC detection of watermelons by means of visible/near infrared (Vis/NIR) diffuse transmittance technique. Vis/NIR transmittance spectra of intact watermelons were acquired using a low-cost commercially available spectrometer operating over the range 350~1000 nm. Spectra data were analyzed by two multivariate calibration techniques: partial least squares (PLS) and principal component regression (PCR) methods. Two experiments were designed for two varieties of watermelons [Qilin (QL), Zaochunhongyu (ZC)], which have different skin thickness range and shape dimensions. The influences of different data preprocessing and spectra treatments were also investigated. Performance of different models was assessed in terms of root mean square errors of calibration (RMSEC), root mean square errors of prediction (RMSEP) and correlation coefficient (r) between the predicted and measured parameter values. Results showed that spectra data preprocessing influenced the performance of the calibration models. The first derivative spectra showed the best results with high correlation coefficient of determination [r=0.918 (QL); r=0.954 (ZC)], low RMSEP [0.65 degrees Brix (QL); 0.58 degrees Brix (ZC)], low RMSEC [0.48 degrees Brix (QL); 0.34 degrees Brix (ZC)] and small difference between the RMSEP and the RMSEC by PLS method. The nondestructive Vis/NIR measurements provided good estimates of SSC index of watermelon, and the predicted values were highly correlated with destructively measured values for SSC. The models based on smoothing spectra (Savitzky-Golay filter smoothing method) did not enhance the performance of calibration models obviously. The results indicated the feasibility of Vis/NIR diffuse transmittance spectral analysis for predicting watermelon SSC in a nondestructive way.

GREENHOUSE TOMATOES FLAVOR AS INFLUENCED BY TECHNOLOGICAL INPUTS

There are many complex factors that determine the flavor of tomato fruit. The intensity of flavor is determined largely by the amount of sugar, the organic acid content and the volatile compounds composition. Typically, human taste find best flavor associated with high soluble solids and soluble solids/titratable acidity ratio. High sugar and high acid contents generally have a favorable effect on taste. Commercial fresh tomato production is not always geared to produce the most flavorful fruit, since other economic concerns must also be considered. In addition to primary factors (such as tomato variety selection, system of culture and growing conditions), proper plant nutrition can also positively contribute to tomato flavor. The research followed to establish the influence of fertilization on some tomatoes fruit flavor characteristics (soluble solids, total sugar, titratable acidity) and was organized as a poly-factorial experience with three experimental factors: 1. system of culture: soil and organic substrate 2. basic soil fertilization with two treatments (simple doze and double doze); 3. additional fertilization consisted of radicular and radicular + foliar treatments. Cronos F1 was used as biological material. Soluble solids content (SSC) is of prime concern in fresh tomatoes due to the important contribution of sugars and acids to the overall flavor of the fruit. Likewise, an increase in SSC would also improve the nutritional value of tomatoes. The doubling of basic fertilization dozes increased the SSC in case of soil culture from 6.05% to 6.55%. Not the same effect was recorded in case of organic substrate culture where the SSC values (as main component of dry matter) were lesser maybe because of the higher obtained yields and due to the reverse correlation between the yield and dry matter content of fruits. Fruit development in tomato is often accompanied by the depletion of foliar potassium to the detriment of both yield and fruit quality (Chapagain, 2004). In attempt to restore high foliar levels of K in the greenhouse tomatoes a high rate K foliar fertilizer (10:5:26) was weekly applied. Significant response to high K rate of the foliar fertilizer was observed for total sugar content of fruits in case of both systems of culture. It is also well known that higher acid content is related to a superior fruit flavor in tomato (Panagiotopoulos, 1995). Fruits titratable acidity was increased with the foliar fertilization and mainly due to the high K rate of applied fertilizer.

Performance of ‘Coscia’ pear (Pyrus communis) on seven rootstocks in a warm climate

SummaryThe vegetative and reproductive performance of ‘Coscia’ pear (Pyrus communis L.) growing on seven rootstocks [OHF 69, OHF 97, OHF 513 and BP 1 (P. communis), clonal seedling (Davis AxB) of P. betulifolia, and quince BA 29 and EMA (Cydonia oblonga)] were compared over an 8-year period. The trial was conducted at the Experimental Orchard Farm Station in northern Israel, on a well-drained soil with pH 7.5. Trees were planted in December 1998 at a distance of 4.0 m 2.0 m, and trained with a central axis. The most vigorous trees were on P. betulifolia seedling, followed by BP 1 and the three OHF rootstocks (69, 97, 513). All the above rootstocks demonstrated greater vigour than quince BA 29 or EMA. The reason for this effect, at least in part, appeared to be the excellent water status (high midday stem water potential values) of trees on P. betulifolia in comparison with the other rootstocks. The highest cumulative yields per tree were harvested from trees on P. betulifolia and BP 1, followed by the three OHF rootstocks (69, 97, 513). However, the highest cumulative yield of large fruit (> 60 mm) was obtained from trees on P. betulifolia, followed by the OHF series and BP 1. The two quince rootstocks had the lowest cumulative yield, and the lowest yield of large fruit. A positive correlation was found between the vigour of the tree, as affected by the rootstock, and both total yield and fruit size. We conclude that, in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for the weak scion cultivar is the first requirement for establishing an orchard. Fruit quality at harvest and during cold storage were examined for fruit from three rootstocks only. The highest soluble solids content values at harvest were obtained in fruit grown on quince EMA, compared to values for BP 1 and P. betulifolia fruit.

Quality characteristics of fresh-cut watermelon slices from non-treated and 1-methylcyclopropene- and/or ethylene-treated whole fruit

Maintaining the postharvest quality of fresh-cut fruit after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. Analytical quality characteristics of packaged fresh-cut watermelon slices from non-treated and 1-methylcyclopropene (1-MCP)- and/or ethylene-treated whole fruit were investigated. Freshly harvested seedless watermelon (‘Sugar Heart’) were stored 7–14 days in air before exposure to 0, 0.5 or 1.0 μL L −1 1-MCP for 18 h followed by 5 days exposure to 0 or 10 μL L −1 ethylene, all at 20 °C. Following treatment, fruit were processed into wedge-shaped slices, packaged into rigid trays sealed with a high oxygen transmission rate film overlap and stored 1, 6 or 12 days at 5 °C. During storage, fresh-cut watermelon slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated whole fruit maintained similar respiration rates and internal atmospheres of CO 2 and O 2 and were of similar quality with total aromatic volatile concentrations decreasing and puncture firmness, soluble solids content (SSC), cut surface pH and color remaining relatively stable. In contrast, fresh-cut slices from fruit treated with ethylene alone had higher respiration rates and modified package atmospheres containing more CO 2 and O 2; lower firmness, SSC and chromaticity values; higher pH and an altered volatile profile compared to those of slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated fruit. The 22 most abundant volatiles were various aldehydes, alcohols and ketones. During storage, many individual volatiles decreased in concentration but some increased including ( Z)-6-nonen-1-ol, a volatile having a pumpkin-like aroma. The results indicated that low dosage 1-MCP treatments prior to ethylene exposure of whole watermelons prevented ethylene-mediated quality deterioration in fresh-cut slices stored under modified atmosphere conditions at 5 °C.

Dielectric relaxation in complex systems: quality sensing and dielectric properties of honeydew melons from 10 MHz to 1.8 GHz

Based on new data treatment methods, it is possible to identify the fitting function for the complex permittivity ε(jω) measured for a complex system representing plant tissues of honeydew melons in the frequency range (107 to 1.8×109 Hz) at 25°C. The identified fitting function contains 9 fitting parameters and well describes the plant tissue permittivity. These parameters vary for different tissues; their correlation behavior with respect to soluble solids content (SSC), tissue density (TD) and moisture content (MC) are found by a new approach based on the statistics of the fractional moments (SFM). These correlation dependencies expressed in the form of correlation functions can be used for quality sensing of different complex systems, in particular, for ripe fruits and vegetables, where direct relationships between molecular and fitting parameters are not easy to find. These correlation functions can be used for practical purposes to construct a desired calibration curve with respect to quality factors, as for example, moisture content or degree of maturity, expressed in terms of SSC value. The discovered common ``universality'' in dielectric behavior of such complex materials as plant tissues opens a possibility to use dielectric spectroscopy as a nondestructive method of control in analysis of electrical behavior (measured in the form of complex permittivity or impedance) for other complex materials.

Mineral and organomineral fertirrigation in relation to quality of greenhouse cultivated melon

Fertirrigation of melon still presents problems in relation to the type of the fertilizer used, mainly the biofertilizers. This experiment, installed in Uberaba, MG, Brazil, in a plastic module greenhouse of 768 m², tested treatments consisting of the conventional mineral fertirrigation and the organic fertirrigation, using two frequencies: daily and weekly. The best yields were obtained with daily fertilizer application, with superiority in relation to biofertilizers, with yield of 45.5 t ha-1 of fruit. This value was higher as compared to chemical products, that lead to a yield of 42.4 t ha-1. The weekly fertigation had lower productivities, and in this case, the biofertilizers also overcame the mineral, on the average 2.0 t ha-1. The best melon soluble solids values were obtained for the daily application of fertilizers, and the best treatment (P < 0.05) was the organic daily fertigation, with values of soluble solids content of 13.60° brix, followed by the daily chemical fertigation, with values of 12.52°. On the average, the amounts of soluble solids in melon were superior to the average found for Brazilian melons. Differences were not verified among the treatments for the variables pulp thickness and fruits pH. Regarding the peel thickness, the application of organic fertilizer sources presented a slight superiority in relation to chemical fertilizer treatments. No differences were verified among treatments in relation to the amount of fruits protein.

'Puzol': A Facultatively Parthenocarpic Hybrid of Pepino (Solanum muricatum)

Received for publication 18 Dec. 2000. Accepted for publication 17 July 2001. This contribution was financed by CICYT (AGF 99-0552), CICYT and EU (1FD97-0137) and INIA (OT99-002-C2-2). Pepino (Solanum muricatum Aiton) is a vegetatively propagated Andean crop that is being introduced as an alternative vegetable crop for protected cultivation (Prohens et al., 1996). The pepino is not an exacting plant and can be grown, with few modifications, with the same techniques used for tomato. Pepino fruit is very versatile and can be eaten at different ripening stages (Sanchez et al., 2000). When the fruit is ripe, it has a golden-yellow ground color and can be used as a fruit for desserts, in fruit salads, or in elaborate dishes with seafood, ham, etc. When the fruit has reached final size, but only has an incipient yellow color, it can be used in the same way as cucumber (Cucumis sativus L.). Its high content in vitamins indicates good prospects for pepino (Nuez and Ruiz, 1996). A common practice has been to use fruits from pepino cultivars both for salad and dessert uses, depending on their ripening stage. However, fruits of salad cultivars are too low in sugar for use as dessert fruit. On the other hand, pepinos from dessert cultivars may have an inadequate texture or shape for use in salads. Therefore, selection in pepino should be based on the intended use of the fruit. When pepino fruits are to be used as dessert fruit, sweetness is a very important characteristic, and fruits should have a soluble solids content (SSC) higher than 8% (El-Zeftawi et al., 1986). However, when used unripe in salads, high SSC values are not as important (values between 6% and 9% are acceptable), and other characteristics, such as elongate shape (to be cut in slices like cucumber) and crispy texture, are of main relevance in breeding programs. As a result of a breeding program to obtain a pepino cultivar for use in salads, we have developed a parthenocarpic hybrid cultivar (‘Puzol’) with a high yield in a wide range of environmental conditions. ‘Puzol’ (Fig. 1) has elongated, large, and uniform-sized fruits that have a crispy texture and no sour aftertaste, which is often associated with parthenocarpy. Currently, ‘Puzol’ is being commercially grown in the Spanish Mediterranean area. This cultivar combines heterosis for vigor and yield characteristics resulting from unrelated parents (Prohens and Nuez, 1999) and facultative parthenocarpy conferred by the the taste. ‘6-21’ has elongated fruits, with a high SSC and an excellent flavor for a dessert fruit, but a moderate yield. ‘Puzol’ was initially selected for its high yield among a population of different hybrids obtained between parental plants from different origins. Pepino plants from crosses between unrelated parents are usually heterotic for yield characteristics (Prohens and Nuez, 1999). Due to its highly heterozygous nature, ‘Puzol’ does not breed true. In the same way, because ‘9-2’ and ‘6-21’ show a certain degree of heterozygosity, the only way to maintain the characteristics of this cultivar is through vegetative propagation, which is the common reproductive practice for this species (Nuez and Ruiz, 1996).

Evaluation of the fungicidal properties of plant extracts to reduce Rhizopus stolonifer of ‘ciruela’ fruit (Spondias purpurea L.) during storage

Rhizopus stolonifer is one of the main postharvest pathogens of ‘ciruela’ fruit (red mombin) (Spondias purpurea L.) during handling and storage. To evaluate the fungicidal potential of plants indigenous to the state of Morelos, Mexico, aqueous extracts of leaves or stems of 19 different plant species were tested against Rhizopus development in vitro and in vivo. Extracts were applied to fruit of three botanical varieties of ciruela: fruit skin turning green to red, green to yellow or green to orange, grown throughout the year over dry and wet seasons. In vitro evaluations were carried out to observe mycelial growth, sporulation and conidial germination. Evaluations on fruit were percentage and disease severity, soluble solids content (SSC) and weight loss after 4 days storage at ambient temperature. In general, leaf extracts had better fungicidal effects than stem extracts. For in vitro studies, leaf extracts inhibited sporulation and spore germination more than mycelial development. Leaf extracts of Annona cherimola, Bromelia hemisphaerica and Carica papaya inhibited Rhizopus sporulation and rot development on the yellow variety whereas extracts of Casimiroa edulis reduced R. stolonifer rot on red ciruela. Infection spread from 25 to 100% of the fruit surface depending on extract or ciruela variety. After storage, SSC values were not significantly different. Less weight loss was observed for the orange variety than the other varieties. Further studies need to be undertaken to isolate the active compounds from those extracts with fungicidal potential. © 2000 Elsevier Science B.V. All rights reserved.

Effects of relative humidity on apple quality under simulated shelf temperature storage

The effects of relative humidity (RH) on the quality of ‘Braeburn’ and ‘Jonagold’ apples were studied at 20°C under 30, 65 and 95% RH conditions. The aim of the research was to assess the effects of RH on apple quality under retailers’ shelf temperatures. Mealy texture may develop by holding apples at high RH (95%), and 20°C for some time depending on the cultivar. The 65% RH treatment is a typical RH for shelf life and 30% is a low RH condition. Apple firmness, expressible juice content, weight loss, pH, soluble solids content (SSC), and some other quality parameters were determined instrumentally. Scanning electron microscopy (SEM) was applied to investigate the structural changes at the level of the cell wall. The RH had significant effects on weight loss, firmness, and SSC values. Acoustic non-destructive measurements showed that the firmness of apples decreased more slowly at higher RH, and the weight loss was faster at low RH for both apple cultivars. Mealiness was observed under high RH (95%) and was associated with low tensile strength and an increase of cell separation following the simulated shelf storage. Higher RH could maintain apple firmness and weight better than lower RH but it tended to promote the development of mealy texture at 20°C.

Variation in the Performance of Fruit Maturing Time, Fruit Weight, and Soluble Solids Content in Oriental Persimmon Grown at Akitsu, Japan and Meixian, China.

Fruit maturing time (FMT), fruit weight (FW), and soluble solids content (SSC) in 15 identical persimmon (Diospyros kaki Thunb.) cultivars were evaluated at Akitsu, Hiroshima of Japan and Meixian, Shaanxi of China. The data were subjected to two-way analysis of variance, with the factors of location and cultivar. This model of analysis-of variance was applicable because the residue estimates approached a normal distribution as determined by the Kolmogorov-Smirnov one-sample test. FMT and FW were greatly and significantly affected by location and cultivar (P 0.05). Coefficients of correlation between the two locations were 0.79**, 0.89**, and 0.52* for FMT, FW, and SSC, respectively. The cultivars evaluated at Akitsu, on the average, matured 18 days later and weighed 70g more than did those at Meixian. The mean values for SSC differed little between the two sites. These results indicated that cultivar performance in one location could be estimated from that in another location by incorporating the correction constant for the mean differences in FMT and FW between locations.

BERRY & JUICE QUALITY RESPONSE TO CANOPY MANAGEMENT & ETHEPHON IN `RELIANCE' TABLE GRAPES

Grape clusters were subjected to one of two levels of leaf removal, one of two levels of preharvest ethephon spray, and either thinned to a basal cluster or left unthinned. Ethephon was applied at a concentration of 100 ppm two weeks after veraison. Affects on soluble solids content (SSC), titratable acidity (TA), pH, hue, chroma, and L, a, b values were not consistent. In 1989, light exposed clusters of thinned vines had significantly higher SSC. In 1990, when ethephon was applied to non-thinned vines, light-exposed clusters had higher SSC values than non-exposed clusters. Light, ethephon, or thinning in 1989 and light or ethephon in 1990 significantly increased TA. Ethephon in 1989 and light in 1990 significantly higher pH in 1989, and ethephon-treated clusters from thinned vines had significantly lower pH in 1990. Juice from light treatments in 1990 had significantly higher L, a, b, and chroma values. Ethephon significantly increased the “a” value of juice in 1989, and light significantly increased the “b” value. Hue was significantly different for light and ethephon treatments in 1989.

Effect of environment and harvest date on maturation and ripening of kiwifruit in British Columbia

Kiwifruit (Actinidia deliciosa var. deliciosa ’Hayward’ (A. Chev.) C. F. Liang et A. R. Ferguson) were harvested periodically from 10 Oct. to 21 Dec, 1990 to monitor "on-the-vine" ripening in three environments (field; greenhouse, covered for the full season; greenhouse, covered until pollination and then uncovered). Fruits were also placed in 1 °C, 97% RH storage on 19 Oct., 22 Oct., 25 Oct., and 3 Nov. and sampled periodically to monitor their "in storage" ripening. Field-grown fruit remained firmer than greenhouse-grown fruit (both treatments) on the vine, and in storage for about 7 weeks following harvest. There was little difference in the harvest maturity date of fruits from the three growing environments. In storage, fruits showed no differences in soluble solids content (SSC), and tissue deterioration (as measured with firmness and chlorophyll fluorescence) due to growing environments. The peak SSC values attained by fruits harvested prior to reaching a SSC of 6.2% were significantly lower than for fruits harvested after the SSC had reached or surpassed 6.2%. Later-harvested fruits remained firmer in storage than those harvested earlier. Changes in the fruits’ SSC and firmness were similar whether on the vine or in storage; however, fluorescence decline was more rapid in storage.Key words: Actinidia deliciosa, soluble solids content, fruit firmness, post harvest, chloroplast, temperature