Effect of drying technologies on bioactive compounds maintenance in pumpkin by-products

ArticleDuring the pumpkin processing large amounts of waste material as a combination of pumpkin peel, seeds and the flesh between seeds has produced. Therefore it is important to investigate the possibilities for using the pumpkin residues. The aim of this resea rch was to investigate the effect of different drying technologies on maintenance of bioactive compounds in pumpkin by - products. Two pumpkin residue products of Hubard group pumpkins were used to obtain pumpkin powder: residue products formed in the proces s of extracting industrial pumpkin purée by heating it in a heat exchanger and treating through a sieve of pulpier; residues resulting from pumpkin juice extraction process mechanically pressed from fresh, chopped pumpkins. In order to be able to choose th e most suitable drying technology pumpkin by - products were dried in the microwave - vacuum, convective (at 40, 50, 70 and 80 °C ) and freeze - drying type dryers. For all samples total carotenes, the ascorbic acid, total phenols content (TPC) and antiradical ac tivity (DPPH ̇, ABTS ̇+ ) were determined by using standard methods. The highest total carotenes content was retained in freeze - dried pumpkin powders. The most suitable drying method for obtaining pumpkin powder with the highest ascorbic acid, total phenolic content and antiradical activity is drying in convective type drying at 80 °C temperature

Changes in the nutritional value of breakfast cereals containing germinated spring grain flakes during storage

ArticleTh e aim of current research was to assess the nutritional value of breakfast cereals containing germinated spring grain flakes and its changes after 6 month storage. Three types of breakfast cereals were prepared and packaged in two types of Standup pouches – Pap50g/Alu7/Pe60 (AL), Pap40g/PELD20/PE40 (PE). For the accelerated shelf life test the samples were stored at 35 ± 2 °C and dietary fibre, protein, fat, B - group vitamins, sugars, total phenol content and DPPH, ABTS+ radical scavenging activity were dete rmined. Developed breakfast cereals have high nutritional value and all are high in fibre and thiamine. Additionally, sample S2 is source of protein, riboflavin, niacin, and S3 – is source of riboflavin and high in niacin. Comparing total phenolic content and antioxidant capacity of tested samples S3 showed the highest values. Storage and selected packaging influenced stability of nutrients, and for S1 and S2 AL showed bett er results whereas for S3 – PE

The Relationship of Anthocyanins with Color of Organically and Conventionally Cultivated Potatoes

Many of the compounds present in potato are important because of their beneficial effects on health, therefore, are highly desirable in the human diet. Potato tubers contain significant amounts of anthocyanins. The aim of this research was to determine the content of anthocyanins and its relationship with the colour of organically and conventionally cultivated potato varieties. In the research eight potato samples of three potato varieties were analysed on anthocyanins, dry matter content and colour. Obtained results show that there was no significant influence on amount of anthocyanins between different cultivation environments (p>0.05) while between varieties-significant difference (p<0.05). Strong correlation between the amount of anthocyanins and colour was determined

Comparison of phenolic compounds and antioxidant activity of fresh and freeze-dried potatoes

ArticlePotatoes (Solanum tuberosum L.) contain a wide range of compounds with health benefits, and different techniques have been developed for the determination of these compounds. Freeze-drying is a common method for the preservation and preparation of samples for the analyses of bioactive compounds, but it is well known that drying influences the composition of food products. The aim of the current study was to compare phenolic compounds and antioxidant activity of fresh and freeze-dried potatoes. In the experiment 11 cultivar potatoes grown in experimental fields of the Institute of Agricultural Resources and Economics in 2016 were analysed. Potatoes were freeze-dried. Homogenized fresh and freeze-dried samples were extracted with an ethanol/water (80/20 w/w) solution. Total phenolic content (TPC) was determined using the Folin-Ciocalteu method, and the antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH˙) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The highest TPC and radical scavenging activity were determined in cultivars ‘Peru Purple’ and ‘Blue Congo’ potatoes. Freeze-drying influenced all the tested parameters but more significantly the TPC, and for certain cultivars a reduction of more than 30% was observed. A strong correlation between TPC, DPPH and ABTS in fresh and freeze-dried samples was observed, r = 0.81, r=0.93, r = 0.92, respectively. It could be concluded that the effect of freeze-drying on TPC and antioxidant activity is cultivar dependent