Drying is one of the most important step in raisin processing. During this step, initial moisture content is decreased up to 15 – 17 percent (d.b).In this research, the effect of two-tempreture and pretreatments on time and drying rate of Thompson seedless grape was studied. Drying was in two steps: First step; temperature at four levels of 50, 60, 70, and 80 oC and secound step which samples were placed at two temperatures. In this step, samples were placed at 80 oC and while moisture content was reduced to 50%, temperature was reduced to 70, 60 and 50 oC. Four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydracids and no pretreatment was performed.According to the results of the ANOVA, factors such as temperature, two-temperature and pretreatment have significant effects on drying time and average drying rate. Drying time of grape with two-temperature in comparison with drying time of constant temperature was decreased, up to 61% for some pretreatment. Maximum and minimum activation energy were determind 893.9, 4538.8 kj/kg.

Introduction: Drying is one of the most important step in raisin processing. Temperature, air velocity and pretreatment are important factors in grape drying process and the quality of final product.Materials and Methods: In this research, the effects of the following conditions on the quality of Thompson seedless raisin were studied: temperature at four levels of 50, 60, 70, and 80oC, air velocity at three levels of 1, 2 and 3 m/s, and four pretreatments consisting of hot water, %5 potassium carbonate, with %0.4 olive oil, %0.5 sodium hydroxide and no pretreatment.Results: The results indicated that factors such as temperature, air velocity and pretreatments have significant effects on browning rate and rehydration.Similarly temperature and pretreatment factors have significant effect on acidity and only temperature factor has significant effect on shrinkage.Conclusion: Raisins dried at 60 and 70oC and pretreated in hot water, %5 potassium carbonate and %0.4olive oil and %0.5 sodium hydroxide provided better quality.

Partial rootzone drying (PRD) is a new irrigation technique which improves water use efficiency without significant yield reduction in grape. To study the effects of partial rootzone drying and green pruning on yield and yield quality of Thompson seedless grape a split plot experiment with randomized complete block design and three replications was conducted. The experiment was performed in Takestan. The experimental treatments were irrigation and pruning and each treatment had three levels. During growing season, half of the root system was maintained in a dry state, while the rest was irrigated (PRD). The irrigation levels were: full irrigation (irrigating both sides of root zone), drying left side of rootzone (irrigating from north direction) and drying right side of rootzone (irrigating from south direction). Pruning levels included light, medium and heavy green pruning. The analysis of variance (ANOVA) of data showed that the effects of irrigation were significant on pH and TSS of grape juice at 5% level but there were no significant differences between irrigation treatments with respect to grapevine yield indicating that water requirement of grapevine can be reduced to half without significant yield reduction. The effects of pruning were also significant on grapevine yield, berry weight and diameter, cluster weight and length and sultana production. The interactive effects of pruning and PRD were significant on weight and diameter of berry, weight and length of cluster and Sultana production Full irrigation with medium pruning, irrigation from north with medium pruning and irrigation from south with light pruning had higher grape yield than the other treatments. PRD reduced shoot and lateral shoot growth about 8 and 30% respectively compared with full irrigation.

Introduction: Achieving optimum drying conditions can affect the processing time and improves the quality of raisin produced.Materials and Methods: In this research, the effect of two- step temperature and pretreatments on some qualities of the final product in drying of Thompson seedless grape were studied. Drying was carried out by two methods. In the first method of drying, the grapes were subjected to conslaut temperatures of 50, 60, 70, and 800C. In the secound method of drying the grapes were subjected to a temprature of 800C and when the moisture content of the product was reduced to 50%, the temperature was reduced to 50, 60 and 700C and the processing was continued at the set temprature. Four pretreatments consisting of hot water, %5 potassium carbonate, %0.4 olive oil and %0.5 sodium hydroxide were performed on the samples. A blank sample without pretreatment was used as a control.Results: The results indicated that factors such as temperature and pretreatment have significant effects on browning rate, dehydration and shrinkage, but there was not a significant effect on the acidity.Conclusion: Raisins dried at two-step temperatures by changing the second step’s temperature to 600C and pretreated with %5 potassium carbonate, %0.4 olive oil and %0.5 sodium hydroxide had better quality.

To evaluate the effect of integrated soil fertility management (ISFM) on growth and nutritional balance of Thompson Seedless grape (Vitis vinifera L. ), an experiment was conducted in a randomized complete block design including four treatments with three replications at Urmia, Iran, during 2020 and 2021seasons. Treatments included T1= check (no fertilization), T2= farmers’ conventional fertilization, T3=optimum fertilization of mineral nutrients (30-80 g Urea, 80-100 g potassium sulfate and 50 g zinc sulfate/vine depending on the location) and T4= ISFM (200 ml N fixer bacteria inoculant, 300 g mycorrhizal fungal, 80-100 g potassium sulfate, 15-35 g zinc sulfate, 500 g manure/vine, depending on the location). Results indicated no significant difference among the study sites in terms of cluster weight, chlorophyll index, titratable acidity (TA) and total soluble solids (TSS) of fruits, but a significant difference was observed between macro-and micronutrients, except for iron (Fe). The cluster weight was increased in all fertilized treatments compared to the check (p≤ 0. 05). Grapes increase in T3 and T4 compared to T2 was 2. 27 and 4. 04 kg/vine, respectively. The leaf chlorophyll index increased in T4 by 10. 99% and 9. 69%, respectively, compared to T2 and T3. TA showed a significant decrease in T4 compared to T1 by 16. 09% (p≤ 0. 05). However, TSS accumulation showed the highest value in the T4 (p≤ 0. 05). There was no significant difference between T3 and T4 in terms of these two qualitative characteristics. Evaluation of nutritional status using compositional nutrient diagnosis (CND) norms in control treatments indicated that, on average, the order of nutritional requirements of macro-and micronutrients were K=Ca>Mg>N>P and Fe>Zn>Mn>Cu>B, respectively. The lowest nutrient balance index (9. 02) was obtained in the T4 and the highest value was observed in T1 treatment (35. 02). In general, it is concluded that due to the significant increase in quantitative and qualitative factors of grape yield with ISFM, this technology was the best for balanced fertilization program and optimum fruit production in vineyards.

Moisture sorption isotherms are useful in food dehydration, storage and packaging. Because of the complex food composition, experimental measurements are necessary for prediction of the isotherms. Moisture sorption isotherms of Thompson seedless raisins were determined at 30, 40, 50, 60, 70 and 80oC, using the standard static gravimetric method developed by the European cooperation project COST 90. GAB, Smith, Oswin, Halsey, Henderson and Arcy-Watt equations were fitted to the experimental data. The experimental data were fitted well with D’Arcy-Watt equation at 30 to 70 and with GAB equation at 80ºC. The Isosteric heat of sorption was determined (4.79) kj/mol.

In order to investigate the viscoelastic properties of Thompson seedless grapes in ripening, relaxation tests were carried out on whole berry, flesh and skin of the fruit. Samples were harvested weekly from a grapevine for seven consecutive weeks and relaxation test was done using a texture analyzer after sample preparation. The first term of generalized Maxwell model with three elements was determined using a series of assumed data and then the experimental data were evaluated by the model. The results showed that the magnitude of initial stress (stress at time zero) required to create a fixed strain on whole fruit decreases during ripening period when oBrix of the fruit increases from 16.0±0.45 to 22.5±0.25, but the relaxation time remains almost constant at the range of 41.681 to 45.630 s. Based on results, elastic behavior of the skin enhances and firmness of flesh increases during fruit growth and ripening. According to the results, the skin as compared with the flesh plays a main role on the behavior of viscoelastic alterations of whole fruit. Also on the basis of results obtained by non-linear regression analysis, amount of elastic components of the model raises for flesh and declines for skin and whole berry through ripening. The generalized Maxwell with three elements was the best in fitting experimental data with highest determination coefficients.

Drying is one of the most important steps in raisin processing. During this step, initial moisture content decreases up to 15-17% (db) for suitable storage. Achieving optimum drying conditions can affect the processing time and improve raisin quality. Temperature, air velocity and pretreatment are important factors in the quality of the grape drying process. In this research, the effect of temperature at 50oC, 60oC, 70oC, and 80oC, air velocity at 1, 2 and 3 m/s, and four pretreatments (hot water, 5% potassium carbonate, 0.4% olive oil, 0.5% sodium hydracids) and no pretreatment were measured. Diffusivity and activation energy of all treatments were determined. The results of ANOVA showed that temperature, air velocity and pretreatment have significant effects on drying time and average drying rate. Pretreatment has a significant effect on the drying process and decreases the drying time up to 69% at some temperature levels. Also, increasing the temperature decreases drying time up to 66% for some pretreatments. Increasing the hot air velocity decreases it about 8.6%.

For a breeding of grape to obtain new superior raisin and table cultivars, seedless cultivars of Askary, Yaghooti, Bidane Sefid and Bidane Ghermez were selected as male parents, while seeded cultivars of Muscat of Hamburg, Ghezel Dzum, Dizmary, Rajabi Sefid, Ali Baba, Alhaghi Ghermez, and Tabarzehchosenas female parents. Out of 1400progenyobtainedfrom 26 different crosses, 381 of them, which produced fruits, were evaluated during the growing seasons of 2006 & 2007. For an evaluation of progenies, three fruit clusters were randomly harvested from each progeny. Five berries were randomly selected from each cluster and their traits registered. For stenospermic trait evaluation, 10 big berries were selected from each cluster. Progenies were divided into four groups of completely seedless, semi-seedless, semi seeded and completely seeded, as according to seed trace or seed weight. Some of the seedless progenies carried desirable traits such as large and fleshy berries, early ripening, proper attachment of berries to the cluster along with low density of berries, so that they were superior as compared to other Iranian seedless cultivars. Among all progenies, the 121, B98, 173,K67, L125, L127, S52, S55, K93, R84, R80, A119 and B96 genotypes stood in the seedless class. Also some such semi- seedless and completely seeded genotypes as B95, S26, 138, N81, L131 and N84 are of so desirable and noticeable traits as semi-seed lessens and big berry that they have to be given due consideration too.

Moisture desorption isotherms are useful in food dehydration, storage and packaging. Due to the complex food composition, theoretical prediction of the isotherms is not possible and experimental measurements are necessary. Moisture desorption isotherms of Thompson seedless raisins were determined at 30, 40, 50, 60, 70 and 80oC, using the standard static gravimetric method developed by the European cooperation project COST 90. GAB, Smith, Oswin, Halsey, Henderson and D’Arcy-Watt equation were fit the data. The experimental data were fitted well with Halsey equation at 30oC and 40 to 80oC, with D’Arcy-Watt equation. So, Isosteric heat of desorption data obtained at different moisture content.