Margareta Hägg

Effects of preparation procedures, packaging and storage on nutrient retention in peeled potatoes

The effects of preparation procedures and packaging on vitamin C, dietary fibre, sugars, ash and moisture contents were studied in prepeeled packaged potatoes during two cultivation seasons. The potato cultivars Bintje, Van Gogh and Nicola were studied. Potatoes of the Nicola cultivar had the highest initial vitamin C and sugar contents. Retention of nutrient contents in packaged, prepeeled potatoes was very good after a 7-day storage period. Vitamin C contents were higher in packaged potatoes than in fresh tubers when ascorbic acid was used in the washing solution but the levels decreased during the 7-day storage period. When calcium chloride was added as well into the washing solution vitamin C contents remained high throughout the storage period. These results show that it is possible to preserve the nutritional contents of packaged potatoes over a 7-day storage period. Cooking decreased vitamin C contents by about 30% and keeping the potatoes hot for 1 h after cooking decreased vitamin C contents a further 10%.

Shelf-life of prepeeled potato cultivated, stored, and processed by various methods.

The effects of cultivation conditions, winter storage, peeling method, browning prevention chemicals replacing sodium bisulfite, and packing methods on the sensory, nutritional and microbiological quality of pre-peeled potato were examined. Two different cultivation lots of the potato variety Van Gogh were used. Cultivation and harvesting conditions and peeling method were the most important facts reducing the sensory quality, especially the appearance, of prepeeled and sliced potatoes. Cooking and baking of potatoes decreased the appearance defects detected in raw potatoes. The levels of vitamin C in packaged samples decreased during winter storage. Cooking for 10 min and keeping potatoes at 60 degrees C for 1 h after cooking also decreased the content of vitamin C. In potato samples immediately after treatments aerobic bacteria were present at levels of 400 to 2,950 CFU/g and lactic acid bacteria at levels of 8 to 16 CFU/g. The number of aerobic bacteria did not increase during storage, and the number of lactic acid bacteria increased at the most to 90 CFU/g. Peeling, washing and packaging methods, cultivation conditions, and winter storage did not have important effects on the number of microbes present.

Decreased nitrogen rates and irrigation effect on celery yield and internal quality

The effect of decreased nitrogen rates (90, 60 and 30 kg N/ha) with and without irrigation on celery yield quantity and internal quality were studied in field experiments in 1993 and 1994. The decreased nitrogen rates reduced yields in both years. In the dry and warm conditions of 1994 nitrogen × irrigation interaction was clearly observed; irrigation increased yield more at higher nitrogen rates than at lower nitrogen rates. In the rainy conditions of 1993 irrigation did not effect the yield level.On the other hand, in both years, decreased nitrogen rates increased dry matter, vitamin C and dietary fiber contents, and nitrogen had a minor effect on total sugar content. In 1994 alpha- and beta carotene and thiamin were also analyzed but nitrogen had no effect on them. Irrigation increased dry matter and total sugar contents at the two lowest nitrogen rates in 1994, but decreased vitamin C contents in both years. There was also slight evidence that irrigation might decrease alpha- and beta-carotene and thiamin contents.

Soil forming and plant density effects on carrot yield and internal quality

The effects of soil forming (SF) and plant density (PD) on the carrot yield, mean root weight and internal quality was studied in field experiments in 1993 and 1994. ‘Fontana BZ’ carrots were grown in flat land, a narrow ridge, a broad ridge, and a compacted broad ridge soil configurations with low (LD) and high (HD) target plant densities, four and seven hundred thousand carrots per hectar. The total and marketable yields were larger in flat land and narrow ridge than in the broad- and compacted broad ridges in 1993 and in 1994 at HD. The number of marketable carrots were highest with the flat land soil configurations in both years. A dry spring in 1993 favored flat land growing conditions; in ridges the fine sand dried quickly. SF did not influence the mean weight of a marketable carrot in 1993, but in 1994 the narrow ridge configuration resulted in heavier carrots than the flat land or broad ridge growing conditions. In the climatically more unfavorable year of 1993, SF and PD affected quality; dry matter was lower in flat land than in the ridges. At HD, the flat land soil configuration produced higher glucose and fructose than carrots grown in the narrow and broad ridges. Dietary fiber and vitamin C were higher in narrow ridge than in compacted broad ridge grown carrots. At LD the flat land and broad ridge produced highest and compacted broad ridge the lowest beta-carotene contents; alpha-carotene was higher at LD than at HD.

Preparation and characterization for mineral elements and total dietary fiber and testing for stability of β-carotene of an ARC/CL carrot powder multipurpose candidate reference material

As part of the analytical assurance system of the FAO European Cooperative Research Network on Trace Elements programme an ARC/CL-coded carrot flakes powder (CFP) candidate reference material (RM) has been prepared from a lot of commercial carrot flakes. The candidate RM has been homogenized using a Robot Coupe blender fitted with titanium blades, carefully homogenized in large teflon/polypropylene containers, bottled in 1000 numbered polyethylene containers (20 g samples) and tested for homogeneity. Interlaboratory comparison studies for 9 essential elements, cadmium and total dietary fiber (TDF) based on the AOAC-method resulted in the characterization of the contents of those compounds in the above material. After exclusion of outliers, mean values from at least nine different laboratories based altogether on three independent analytical principles have been used to calculate the recommended concentration ranges for mineral elements. Testing of homogeneity and stability for β-carotene over a period of one year has been additionally carried out. The mean water content in the material amounted to 4.97% and remained stable over a one-year period. Homogeneity of the RM was within 3.0% for almost all included mineral elements as tested for a sample size of 0.5 g. The 95% confidence limits for the mean values of the established recommended concentrations of mineral elements in the present ARC/CL Carrot Powder candidate RM fell within 5% for all the other elements and TDF except for Fe (6.3%) and B (5.7%). The stability of β-carotene in the present candidate RM stored in darkness over a one-year period at room temperature was within 6.3%.

Effects of Preparation Procedures and Packaging Materials on Quality Retention of Grated Carrots

The effects of different washing procedures, packaging materials and long-term storage before processing on the quality retention of packed grated carrots were studied. A shelf life of at least 8 days at 5 °C could be achieved by washing the peeled carrots in 0.01 % chlorine solution and in 0.5 % citric acid solution. The packaging materials tested did not affect the shelf life of grated carrots. Long-term storage before processing was detrimental to the quality of the packed samples.

Effects of Preparation Procedures and Packaging Materials on Quality Retention of Cut Chinese Cabbage

The effects of different washing procedures, packaging materials and long-term storage before processing on the quality retention of packed cut chinese cabbage were studied. A shelf life of at least 7 days at 5 °C could be achieved by two separate washings, the first of which could contain chlorine, and by highly permeable packaging films (O2 perm. 5200 - 5800 cm3/m2 24 h 101.3 kPa, 23 °C, RH 0 %). Long-term storage before processing was detrimental to the quality of the packed samples.