Ulla Kidmose

Changes in texture, microstructure and nutritional quality of carrot slices during blanching and freezing

Thermal processing of vegetables has pronounced effects on the cell structure, often lowering the final textural properties of the product. In order to investigate the effect of thermal processing on carrot, slices were subjected to different blanching and freezing treatments before frozen storage. Microwave-, steam- or water-blanched material was frozen and then stored at −24 °C. Steam-blanched carrots were subjected to blast freezing or cryogenic freezing at different temperatures before frozen storage. The influence of these process conditions on the texture (maximum load and slope), microstructure, dry matter, sugars, carotene and drip loss was investigated. Microwave blanching differed from the other blanching methods by resulting in a heterogenic cell structure. The content of dry matter, carotene and sucrose was higher following microwave blanching. Blast freezing resulted in low maximum load which seemed to be caused by major tissue damage. Concerning cryogenic freezing, lowering the temperature from −30 °C to −70 °C resulted in better preservation of the native microstructure together with an increase in maximum load, which was most pronounced after one month of storage. No significant effect was observed when lowering the temperature from −30 °C to −70 °C for any of the other measured parameters. © 1999 Society of Chemical Industry

Deposition of carotenoids in egg yolk by short-term supplement of coloured carrot (Daucus carota) varieties as forage material for egg-laying hens

BACKGROUND Supplying egg-laying hens with different forage materials may influence egg production and quality. The aim of this study was to examine the short-term effects of standard feed plus 70 g day(-1) per hen of three coloured carrot varieties (orange, yellow and purple) as forage material in comparison with a standard feed control on egg production, egg yolk colour and deposition of carotenoids in the yolk. RESULTS Carrot supplementation reduced feed intakes significantly, but not on a dry matter basis. Orange carrot treatment significantly reduced egg mass production, whereas yellow and purple carrot treatments did not differ from the control. Egg and yolk weights of all carrot-supplemented treatments were significantly lower than those of the control, but yolk percentages were similar. Yolk redness increased significantly in the order control < yellow < orange < purple. A similar trend was seen for yolk yellowness, but yellow and orange carrots reached the same level. Yolk colour and carotenoid contents correlated positively and significantly. In particular, purple carrot treatment increased the yolk content of lutein (>1.5-fold) and beta-carotene (>100-fold) compared with the control. CONCLUSION Supplementing the feed of egg-laying hens with coloured carrots efficiently increased yolk colour parameters and carotenoid contents, which gives opportunities for improved nutritional value of eggs from forage material-supplemented hens.

Chemical composition and sensory quality of bovine milk as affected by type of forage and proportion of concentrate in the feed ration

BACKGROUND The objective of this study was to investigate how some small changes in the forage content of maize and lucerne silage and in the ration between forage and concentrate in the diet of dairy cows affect milk quality. Milk quality was assessed by quantitative descriptive sensory analysis and by analysis of tocopherols and carotenoids as well as fatty acid composition. RESULTS Changing the ratio between maize silage and lucerne silage from 5:1 to 2:1 increased milk fat content of carotenoids (23-27%) and C18:3 n3 (15%), and reduced stale aroma and creamy flavour. Increasing the proportion of concentrates in the feed ration from 0.2 to 0.4 increased energy corrected milk yield (26%), reduced fat content (-10%), increased C18 fatty acids (8-62%) and reduced C16 (-20%) content in milk fat. In addition, this milk type was described by the sensory panel as less oily, less saturated and less yellow. The changes in milk composition were related to differences in feed composition. CONCLUSION The study revealed the potential to produce milk with a distinct composition and sensory quality based on even small changes in the feed composition that are straightforward to implement by farmers.

Quality of sour cherry juice of different clones and cultivars (Prunus cerasus L.) determined by a combined sensory and NMR spectroscopic approach.

Juice was manufactured from seven different sour cherry clones/cultivars and evaluated by quantitative descriptive sensory analysis and (1)H NMR spectroscopy. The sensory evaluation showed a large variation in several sensory attributes between the sour cherry clones/cultivars, which could be divided into two groups on the basis of both the sensory data and the NMR spectroscopic data. These groups were closely related to the genetic background of the clones. Kelleris clones were distinctly different from Stevnsberry and Fanal clones. Hence, (1)H NMR spectroscopic data seem to correlate with sensory quality of different sour cherry clones. In addition, malic acid was the most important metabolite for modeling the two highly correlated sensory attributes sweetness and sourness, whereas the glucose content had a slight effect and the fructose content had no impact on sweetness/sourness. Other metabolites (ethyl acetate, asparagine, ethanol) could be correlated with sensory attributes; however, a direct causal connection could not be established.

Sensory quality and appropriateness of raw and boiled Jerusalem artichoke tubers (Helianthus tuberosus L.)

BACKGROUND The aim of the present study was to investigate the sensory attributes, dry matter and sugar content of five varieties of Jerusalem artichoke tubers and their relation to the appropriateness of the tubers for raw and boiled preparation. RESULTS Sensory evaluation of raw and boiled Jerusalem artichoke tubers was performed by a trained sensory panel and a semi-trained consumer panel of 49 participants, who also evaluated the appropriateness of the tubers for raw and boiled preparation. The appropriateness of raw Jerusalem artichoke tubers was related to Jerusalem artichoke flavour, green nut flavour, sweetness and colour intensity, whereas the appropriateness of boiled tubers was related to celeriac aroma, sweet aroma, sweetness and colour intensity. In both preparations the variety Dwarf stood out from the others by being the least appropriate tuber. CONCLUSION A few sensory attributes can be used as predictors of the appropriateness of Jerusalem artichoke tubers for raw and boiled consumption. Knowledge on the quality of raw and boiled Jerusalem artichoke tubers can be used to inform consumers on the right choice of raw material and thereby increase the consumption of the vegetable.

Estimated nutrient intakes and adequacies in Bangladesh change when newer values for vitamin A, iron and calcium in commonly consumed foods are applied.

A food consumption survey was conducted in rural Bangladesh in January–March 1996 using a 24-h food weighing method. Intakes and adequacies of energy, vitamin A, vitamin C, iron and calcium were estimated for 81 children (aged 24–71 months) and 182 women (aged 18–45 years) using three sets of food composition tables. The local food composition table was modified with newer values for nutrient contents of foods identified as important for the contribution of vitamin A and iron. Significant differences in estimated dietary intakes and adequacies were found for vitamin A and iron when different sets of food composition values were used. This study shows that up-to-date chemical analyses of foods selected on the basis of a high frequency of consumption and a large contribution of the nutrients in focus is a useful approach in improving the quality of food composition tables, resulting in greater accuracy of estimates of nutrient intakes and adequacies.

Good sensory quality and cheesemaking properties in milk from Holstein cows managed for an 18-month calving interval

Extended calving interval (CInt) for high-yielding dairy cows beyond the traditional 12mo has been suggested as a profitable, environmentally and welfare-friendly production strategy. However, concerns exist on whether extending cow CInt, and consequently prolonging lactation length, impairs milk quality. The aim of this study was to compare the quality of milk produced during the extended lactation period to mid lactation. In particular, milk indicators related to udder integrity and cheesemaking properties when cows were fed low- or high-energy diets in early lactation mobilization period. Forty-seven healthy Danish Holstein cows (15 primi- and 32 multiparous) were fed 2 distinct weight-adjusted diets in early lactation: either a high-density diet for approximately 42d in milk (DIM) followed by a low-density diet (n=22), or a low-density diet throughout the whole experiment (n=25). Milk quality was explored at 3 lactation periods: 140 to 175 DIM (P1), 280 to 315 DIM (P2), and 385 to 420 DIM (P3). Lactation period was found to be the main factor affecting milk yield, quality, and cheesemaking properties. Primiparous cows kept the same daily milk yield throughout the studied periods, whereas multiparous cows produced, on average, 10.2kg/d less in P3 compared with P1. Fat, protein, and casein concentrations increased, respectively, by 18, 16, and 16%, from P1 to P3. Cheesemaking properties, such as curd-firming rate, gel strength, and wet and dry curd yield, got an improvement from P1 to P3 and were strongly correlated with milk concentrations of protein and casein. The udder integrity indicators, somatic cells count, level of free amino terminals as an index of proteolysis, and milk pH, remained unchanged throughout the studied lactation periods. Feeding cows either high- or low-density diets during the early lactation mobilization period did not exert any relevant carryover effect on milk composition, and thus had no effect on cheesemaking properties in extended lactation. Further, sensory quality of mid- and extended-lactation milk was assessed by a trained sensory panel. The sensory quality of milk from P3 reflected sensory descriptors related to the increased levels of fat and protein over lactation, but, importantly, milk produced in P3 did not present sensory demerits when compared with milk produced in P1. In conclusion, high-yielding Holstein cows undergoing an 18-mo CInt produced high-quality milk from mid to extended lactation.

Culinary preparation of beetroot (Beta vulgaris L.): the impact on sensory quality and appropriateness.

BACKGROUND Beetroot is a diverse vegetable available in different shapes and colours. The objectives of this study were to evaluate sensory qualities, and sugar and dry matter content of five beetroot varieties in relationship to the appropriateness for raw, boiled and pan-fried preparation. RESULTS Sensory evaluation by descriptive sensory analysis and consumer tests showed clear distinctions between red varieties Taunus, Rocket and Pablo, and the pink-white striped Chioggia and yellow Burpees Golden in raw preparations. However, variety delimination was more difficult after boiling and pan-frying. Different sensory qualities were important for beetroot appropriateness in raw, boiled and pan-fried preparations. Appropriateness of raw beetroots was associated with high sensory scores in beetroot flavour, crispness and juiciness, and low scores in bitterness. Appropriateness of boiled beetroots was related to high scores in beetroot and earthy flavours. Pan-fried beetroot appropriateness was associated with high scores in beetroot flavour, colour intensity and crispness. CONCLUSION This study showed that the quality of raw materials is integral in culinary preparations. These results can be used to guide consumers in the use of beetroot in culinary preparations and subsequently increase consumption.

Eating Quality of Carrots (Daucus carota L.) Grown in One Conventional and Three Organic Cropping Systems over Three Years

The eating quality of carrots (Daucus carota L.) was investigated to evaluate the impact of cropping systems (one conventional and three organic systems) and growing years (2007, 2008, and 2009) on root size, chemical composition, and sensory quality. The content of dry matter, sugars, polyacetylenes, and terpenes as well as the sensory quality and root size were related to the climate during the three growing years. A higher global radiation and a higher temperature sum in 2009 as compared to 2007 and 2008 resulted in larger roots, higher contents of dry matter, sucrose, total sugars, and total polyacetylenes, and lower contents of terpenes, fructose, and glucose. No differences were found between conventional and organic carrots with regard to the investigated parameters. This result shows that organically grown carrots have the same eating quality as conventionally grown carrots, while being produced in a more sustainable way.

Nitrogen split dose fertilization, plant age and frost effects on phytochemical content and sensory properties of curly kale (Brassica oleracea L. var. sabellica).

We investigated how concentrations of sensory relevant compounds: glucosinolates (GLSs), flavonoid glycosides, hydroxycinnamic acid derivatives and sugars in kale responded to split dose and reduced nitrogen (N) fertilization, plant age and controlled frost exposure. In addition, frost effects on sensory properties combined with N supply were assessed. Seventeen week old kale plants showed decreased aliphatic GLSs at split dose N fertilization; whereas reduced N increased aliphatic and total GLSs. Ontogenetic effects were demonstrated for all compounds: sugars, aliphatic and total GLSs increased throughout plant development, whereas kaempferol and total flavonoid glycosides showed higher concentrations in 13 week old plants. Controlled frost exposure altered sugar composition slightly, but not GLSs or flavonoid glycosides. Reduced N supply resulted in less bitterness, astringency and pungent aroma, whereas frost exposure mainly influenced aroma and texture. N treatment explained most of the sensory variation. Producers should not rely on frost only to obtain altered sensory properties.