Agronomijas v stis - Latvijas Lauksaimniecības universitāte

lueberry cultivars were collected from the blueberry collection (7 years old bushes) of the Instituteof Agrobiotechnology (LLU), Jelgava.The samples were analyzed after freezing. After harvesting the blueberries were sorted, frozen inthe freezer PORKKA BF 710 at a temperature of -25±2 °C, then packaged and stored for onemonth in the freezer chamber VTK 201 U at a temperature of -20±2 °C.The contents of titratable acids, soluble solids, ascorbic acid, the total phenols, and anthocyanins offrozen fruits of highbush blueberry cultivars 'Northland', 'Spartan', 'Barkeley', Duke', 'Chippewa','Bluecrop', 'Jersey', 'Blueray', 'Chandler', and 'Bluejay' were analysed.The content of ascorbic acid was determined by titration with a 0.05-M iodine solution (Moor etal., 2005). 25 g of berries were doused with a 100 ml of 6 % solution of oxalic acid andhomogenized for 1 minute. Then the sample was filtered. 2 ml of 1 % solution of starch was addedto10 ml of filtrate and the filtrate was titrated until a change of colour, which does not disappearduring 30 seconds. The content of ascorbic acid mg per 100 g of berries was calculated from thefollowing equation [1]:CVsample= 400 ⋅ , [1]Vstan dardwhere V sample – volume of the iodine solution titrated in a sample, ml;V standard – volume of the iodine solution titrated in a standard solution, ml.Total titratable acids were determined by titration with 0.1 N NaOH (ISO 750:1998) in fresh andfrozen berries.The contents of the soluble solids were determined by refractometer (ISO 2173:2003) in fresh andfrozen berries.Total phenol content was determined by the photometric method with Folin-Ciocalteau reagent(Singleton et al., 1999). For analyses of phenols the Folin-Ciocalteau reagent and 4 ml 7.5 %sodium carbonate was used. After 30 minutes the samples were analyzed with a spectrophotometerat a wave length of 765 nm. As a control solution 1 ml water with 5 ml Folin-Ciocalteau reagentand 4 ml 7.5 % sodium carbonate solution was used. The content of phenols was calculated fromformula [2]:CX = a ⋅10 , [2]where C – content of phenols, mg 100 g -1 ;a – the amount of analyzed sample, g.The results of all analyses were recalculated to 100 g of dry weight.Total anthocyanins were determined by the spectrophotometric method (Moor et al., 2005).Initially 50 g of berries were homogenized. Then 20 g of this volume was doused with 40 g ofethanol and 1.5 M HCl solution (85:15 by volume) and homogenized for 1 minute. Then thesample was filtered, and light absorption at 535 nm was detected with a spectrophotometer. Thesample was diluted until the absorption coefficient was between 0.6 and 0.8. The content mg per100 g was calculated with the equation [3]:whereA⋅v⋅d⋅1000 C =; [3]980⋅mA – absorption coefficient;v – volume of the extraction (90);d – dilution;m – sample weight in g.Results and DiscussionThe total anthocyanins of highbush blueberry cultivars differed between 59 and 119 mg 100 g -1 offresh weight (Figure 1).55