كليدواژه :
ارتعاشات , حمل و نقل , شبيه سازي , زردآلو , كاهش وزن
چكيده فارسي :
حمل و نقل نامناسب محصولات كشاورزي باعث ايجاد آسيب هاي مكانيكي بر روي آن ها مي شود. شكل آسيب بستگي به خواص فيزيكي و مكانيكي محصول و نوع بار وارد شده. ارتعاشات ايجاد شده هنگام حمل و نقل باعث تكان خوردن محصول و برخورد آن با سطوح اجزا ماشين حمل كننده و ديگر قسمت ها مي شود و در نتيجه باعث تغيير شكل بافت هاي آن و ايجاد صدمه مي گردد. در اين مطالعه اثرات فركانس ارتعاش (5،7/5،10 و Hz 12/5)، زمان ارتعاش (15 و 30 دقيقه) و موقعيت قرار گيري داخل مخزن (پايين، وسط و بالا) در شتاب ثابت g 0/7 بر روي ميزان صدمات وارد شده به ميوه زردآلو مورد مطالعه قرار گرفت. ابتدا يا دستگاه شبيه ساز ارتعاشات در آزمايشگاه طراحي و ساخته شد و با استفاده از آن ارتعاشاات حمل و نقل بر روي ميوه ها شبيه سازي و اثر پارامترهاي مختلف بر روي ميزان صدمات بررسي شد. ميزان صدمه بر مبناي اختلاف بين ميزان كاهش وزن ميوه هاي ارتعاش داده شده با تيمارهاي شاهد، برحسب درصد
در نظر گرفته شد. نتايج آناليز داده ها نشان داد كه اثرات فركانس ارتعاش ، زمان ارتعاش و موقعيت قرارگيري محصول داخل مخزن، كه به عنوان منابع تغييرات در نظر گرفته شدند، در سطح يك درصد بر روي ميزان صدمات معني دار است . ارتعاشات با فركانس 10Hz و مدت زمان 30 دقيقه بيشترين صدمات را وارد كرده بودند. ميزان صدمات وارده به ميوه هاي واقع در لايه هاي بالايي مخزن به طور معني داري بيشتر از لايه هاي وسطي و زيرين بود.
چكيده لاتين :
Introduction Mechanical injuries are the mean reason for considerable decay of fresh fruits and vegetables. The production wasted due to the damage in the chain between the grower and the consumer is estimated around 30–40%. The reasons for mechanical injuries are numerous, and are often broadly grouped as impact, abrasion, compression, and vibration damage, based on the type of force acting on the fruit. Impact damage is characterized by a momentary application of force, which may occur when a fruit is dropped, when an object drops on a fruit, or when a fruit rolls into a barrier. In contrast, compression damage involves a static applied force, such as the weight of stacked fruits above the other fruits. Abrasive damage is the result of the rubbing of fruits against each other, or against some other surface. Vibration damage occurs when fruits are subject to vibratory forces, such as during transport. It is thus well known that one of the major causes of mechanical damages to fresh fruit is vibration during transport between farms and retail outlets. This type of stimulus can cause impact, abrasion and compression injuries. Vibration injury may cause only one of these types of damage, or all three. Improper transportation of agricultural materials causes mechanical damage to them. The damage is depend on the physical and mechanical properties of the product and properties of the applied force. Vibration generated by vehicles during road transportation causes shaking of the product, contacting it with a carrier bin and other components, tissues deformation and damage to the product. The objectives of the present study were: (1) to simulate the transport vibration using a vibration simulator under laboratory conditions and (z) to investigate the effects of vibration parameters such as vibration frequency, vibration duration, and fruit position in bin on the damage during apricot fruits transportation.
Materials and Methods The Apricot Fruits used in this study were Shahrodi variety, because it is one of the common commercial varieties grown in Iran. The melons were carefully picked in the 2014 season from an orchard in the Lorestan region and placed in the corrugated containers and carefully handled to the laboratory in order to minimize any bruising before the test. The fruits were stored at 5oc temperature and 90% relative humidity until test times. This research was conducted to evaluate the effects of vibration frequency (5, 7.5, 10 and 12.5 Hz), vibration duration (15 and 30 min) and position in bin (bottom middle and top), on the apricot fruits damage at constant acceleration of 0.7 g. At first, a laboratory vibrator, which simulates the road transportation under laboratory conditions, was designed and used to obtain some factors influencing the damage during the apricot transportation. The damage was described as a difference of fruits weight loss percentage between vibrated and control samples after the tests.
Results and Discussion The variance analysis of the vibration damage data results indicated that all independent variables, namely, vibration frequency (F), fruit position in bin (P), and vibration duration (T) had significant effects on the percentage of weight loss of apricot at 1% probability level (p < 0.01). The effects of the main factors were the most significant. Vibration duration had a larger influence (F=180.185) than fruit position in bin (F=10.271) and vibration frequency (F=60.95) within the range studied. In addition, the interaction effects of the F×P, F×T, and P×T were significant on the percentage of weight loss of apricot at 5% probability level (p < 0.05). Meanwhile, the interaction effect of the F×P×T was not significant on this property (p > 0.05). Vibration with frequency of 10 Hz and duration of 30 min caused higher damage levels. Fruits located at the top position in bin had more damage than the middle and bottom positions.
Conclusion Laboratory studies indicated that that transport vibration causes mechanical damage to apricot fruits. Apricots are sensitive to vibration with 10 Hz frequency and 60 min duration. At the top position in the bin, maximum decay of weight was seen for all treatments. Therefore, the results obtained in the present research suggest that the packaging of apricot fruits to medium-long transportation and for the purpose of exporting to foreign countries should be designed and improved based on the results obtained in this research.
