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Monitoring avocado softening in low-temperature storage using ultrasonic measurements 

Mizrach, A., U. Flitsanov, M. Akerman and G. Zauberman (2000)
Computers and Electronics in Agriculture 26(2):199-207  

One of the main indices of maturity in avocado fruit is its firmness; this changes during the ripening and softening process starting on tree during harvesting, handling and storage. The temperature and time of storage fundamentally influence the firmness of the stored fruit and affects its shelf life later on. Monitoring the softening of fruit during cold storage might enables us to influence its shelf life. The objective of the present work was to study the effects of storage time and temperature on the softening process of avocado fruit, by means of nondestructive ultrasonic measurements. The attenuation of the ultrasonic waves, transmitted through the fruit tissue changes as a result of the progress of the fruit during storage. Several batches of avocado fruits, each stored at a different temperature, were examined until their designated storage time was completed. The fruits were subjected to nondestructive ultrasonic tests as well as to destructive penetration measurements of the tissue firmness. Statistical analysis showed quite good correlation between the firmness and the ultrasonic attenuation. This suggests that the ultrasonic method can be used as a nondestructive means of firmness measurement during low-temperature storage.

Determination of Avocado and Mango Fruit Properties by Ultrasonic Technique
Amos Mizrach (2000)
Ultrasonics 38(1-8):717-722

A nondestructive ultrasonic measurement system was developed for the assessment of some transmission parameters which might have quantitative relations with the maturity, firmness and other quality-related properties of avocado and mango fruits. The system utilizes a set of low-frequency probes arranged to measure the ultrasonic signal transmitted and received over a short distance across the peel. The attenuation of the ultrasonic waves, transmitted through the peel and the attached fruit tissue, changes as a result of the progressive ripening and softening of the fruit during the fruiting season and in the course of storage. The present study quantitatively addressed the linkage between the ultrasonic attenuation and the physiological parameters of the flesh of the fruits. Results were obtained in the time and frequency domain, and the data set was analyzed statistically to identify the relations between the major physiological indices and the ultrasonic parameters. Quantitative relations were developed to describe the linkage between ultrasonic parameters and the maturity, firmness and other quality-related properties in mango and avocado fruits.

Determination of mango physiological indices by near-infrared spectrometry
Ze'ev Schmilovitch , Amos Mizrach, Aharon Hoffman a, Haim Egozi, Yoram Fuchs. (2000)
Postharvest Biology and Technology. 19(3): 245-252.

The objectives of the study were to evaluate the use of near-infrared (NIR) spectrometry in measuring the physiological properties of mango fruit, cv. 'Tommy Atkins' and to establish relationships between the nondestructive NIR spectral measurements and the major physiological properties and quality indices of mango fruit. These include softening of the flesh, total soluble solids content and acidity. Intact mango fruit were measured by reflectance NIR in 1200 to 2400 nm range. NIR models were developed based on Multi-Linear Regression (MLR), Principal Component Analysis (PCA) and Partial Least Square (PLS) regression with respect to the reflectance and its first derivative, the logarithms of the reflectance reciprocal and its second derivative. The above regression models, related the NIR spectra to storage period, firmness, sugar content and acidity. The best combination, based on the prediction results, was MLR models with respect to the second derivative logarithms of the reflectance reciprocal. Predictions with MLR models resulted Standard Errors of Prediction (SEP) of 1.223, 0.161, 17.14 and 37.03, and coefficients of determination of 0.9276, 0.6085, 0.8226 and 0.9380 for TSS, acidity, firmness and storage period, respectively. It was concluded that by using the NIR spectrometry measurement system, in the appropriate spectral range, it is possible to nondestructively assess the maturity factors of mango fruit.

Measurement of avocado softening process at various temperatures using ultrasound
Flitsanova, A. Mizrachb, A. Liberzona, M. Akermanc, G. Zaubermanc 2000
aFaculty of Agricultural Engineering, Technion - Israel Inst. Tech., Haifa 32000, Israel
b Institute of Agricultural Engineering, Agricultural Research Organization (ARO), the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
c Institute for Technology and Storage of Agricultural Products, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel

Postharvest Biology and Technology 20(3):279-286

The low-temperature storage of avocado affects its subsequent softening process and shelf life. One of the main indices of ripeness in avocado fruit is firmness, which changes during the ripening and softening process. The temperature and duration of storage fundamentally influence the firmness of the stored fruit, and monitoring the softening of fruit enables us to regulate its shelf life. The objective of the present study was to use nondestructive ultrasonic tests to elucidate the influences of storage temperature and time on the softening process of avocado fruit. The attenuation of the ultrasonic waves transmitted through the fruit tissue changes as the fruit passes through the various softening stages during and after low-temperature storage. Four groups of avocados, each stored at a different low temperature, and a control group which was stored at room temperature (20 C) were examined during and after their designated storage times, until they reached full ripeness at room temperature. Nondestructive ultrasonic tests and destructive penetration measurements were carried out in order to determine the attenuation and the tissue firmness, respectively, of the avocados. Statistical analysis showed quite good correlation between the firmness and the ultrasonic attenuation, and their dependence on previous storage time-temperature history.
This suggests that the ultrasonic measurements could be used as a nondestructive method of monitoring avocado ripeness during low-temperature storage.

Body Weight and Milk Yield Changes to Evaluate and Model Energy Reserves Handling Along Lactation as Reflected by Body Condition
E. Maltz, A. Mizrach, U. Flitsanov, S. L. Spahr, M. R. Murphy, and J. E. Novakofski

Body condition (BC) score and its changes are currently used to assess the status and handling of the body energy reserves of the dairy cow for management decisions along lactation. This is particularly significant for individual cow management. In the absence of an objective and automatic tool for the scoring of BC, body weight (BW) and milk yield (MY) data, acquired automatically, may be used to assess the body energy reserves handling during lactation. In this study, MY and BW data were analyzed in relation to BC in order to serve as a practical assessment for body energy reserves status and handling along lactation. The subjective traditional BC scores were confirmed by an objective ultrasonic measurement of subdermal fat thickness of the fat layer attached to the skin between ribs 12 and 13. Six multiparous Israeli Holstein cows were measured throughout lactation. The fluctuations of body energy reserves followed the general trends of fat mobilization and deposition that characterize the various phases of lactation. Status and handling of body reserves were found to be related directly and linearly to BW changes only after peak MY. Interpretation of the comparative physiological analysis of both BW, and MY data, allows assessing the status and handling of body reserves in early lactation too. This interpretation allowed modeling BC out of MY, BW, and the ratio between them. This model was applied to an available database of 49 cows. The result confirmed that until an objective and automatic tool for direct measurement of body condition or energy stores is developed BW and MY data can serve as indicators of changes in body energy reserves handling during lactation to improve cow management on individual basis.


A. Mizrach, Z. Schmilovitch, R. Korotic, J. Irudayaraj, R. Shapira

ABSTRACT. Yeast (Saccharomyces cerevisiae spp.) causes unwanted fermentation in apple juice production. Current methods for detecting yeast in the fermentation process are labor intensive and time consuming; therefore, a rapid, reliable method will help ensure consumers a safe and high?quality product. Raman spectroscopy, an advanced optical technique based on light scattering, was investigated as a rapid on?site detection method for yeasts contained in an apple juice droplet. In this study, a dispersive spectrophotometer with a 785 nm diode laser was employed. Chemometric methods such as single linear regression (SLR), partial least squares regression (PLS), principle components regression (PCR), and classification analysis were used to evaluate low?concentration solutions of yeasts in apple juice drops smeared on glass plates. Apple juice samples containing yeast in various concentrations, along with pure samples, were analyzed to predict yeast detection thresholds. Yeast was detected in 85% to 100% of the contaminated samples. The best detection (100%) was achieved at the predicted concentration of 10 CFU mL-1. The results suggest that Raman spectroscopy could be used in apple juice industries as a quality?control tool for rapid, accurate, on?line detection of yeast where a zero tolerance to yeast at 10 CFU mL-1 of pasteurized final product is required.


A. Mizrach, A. Hetzroni, M. Mazor, R. W. Mankin, T. Ignat, J. Grinshpun, N. D. Epsky, D. Shuman, R. R. Heath

ABSTRACT. Medflies (Ceratitis capitata) are among the world’s most economically harmful pests. In addition, the costs of worldwide monitoring and control are expensive, exceeding $800 million per year in Israel and the U.S. alone. Efficient traps are vitally important tools for medfly quarantine and pest management activities. They are needed for control as well as early detection, for predicting dispersal patterns, and to estimate medfly abundance within infested regions. Efficient tools to attract and catch the primary target, namely reproductively viable females, are a particularly important need. The present research aimed to evaluate the attractiveness of male calling song and synthetic sounds to mate-seeking female medflies, as a contribution to the design and testing of a trap (patent pendin ) based on acoustic lures. In order to evaluate the adequacy of the experimental setup, the courtship behavior of female medflies in the presence and absence of calling male flies was observed. Male medfly calling song and synthetic tones were played at various intensities to laboratory-reared and wild female medflies during the morning and early afternoon periods of peak sexual activity. For most treatments, it was found that the laboratory and wild female flies were attracted to sites near broadcasting speakers more than to sites without sound. The strongest effect was with traps broadcasting 150 Hz signals at 67 dB sound pressure level, which attracted 28% more females than non-sound-baited traps. This study indicates that there is a possibility of using sound to enhance the attractiveness of traps to mate-seeking female medflies.


Ultrasonic Technology for Quality Evaluation of Fresh Fruit and Vegetables in Pre- and Postharvest Processes – A Review A. Mizrach  

Increasing public demands for improved quality of fruit and vegetables in the fresh market and the food industry, and growers' expectations receive high prices for premium quality products raise the necessity for fast, accurate, and objective methods for measuring and monitoring product quality along the chain of pre- and postharvest processes, from the field to the consumer. Ultrasound technology provides one of the foundations for a nondestructive, fast, and reliable technique for correlating specific quality-related indices and characteristics of fruit and vegetables with the stages of development during growth and maturation, and in the course of storage and shelf life, until they are ready for consumption. This review summarizes the last two decades of studies, adaptation, modification, and innovation of the ultrasound technology and devices for determination of material properties of fresh fruit and vegetable tissues, in both pre- and postharvest applications. Included are descriptions of the various methods of ultrasonic measurement, the equipment, the procedures for data processing and correlating the measurements of ultrasound parameters with quality indices of fruit and vegetables in the course of the various pre- and postharvest processes. It is concluded that much progress has been made in these fields during recent years. 



28/04/08 | Monday
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