Randi Seljåsen

Sensory quality of ethylene-exposed carrots (Daucus carota L, cv 'Yukon') related to the contents of 6-methoxymellein, terpenes and sugars

Carrots were analysed for taste and odour and for contents of terpenes, 6-methoxymellein and sugars during 3 weeks storage at 15 °C in an atmosphere containing ethylene (1 µl l−1). The ethylene treatment caused an increase in 6-methoxymellein and the conversion of higher amounts of sucrose to fructose and glucose compared to control carrots stored in air. This corresponded to higher sensory scores for bitterness and terpene flavour and a lower score for sweetness, as measured by an expert taste panel. Principal component analysis showed a more expressed bitter taste, earthy flavour, green flavour, terpene flavour and aftertaste in the ethylene-treated carrots. Correlations were found between sweet taste and the content of sucrose (r  = 0.91, p < 0.005) and between the contents of various terpenes (particularly γ-terpinene, limonene and caryophyllene) and terpene flavour, green flavour, aftertaste and bitter taste (r ≥ 0.72, p < 0.05). In the air-stored carrots these off-flavours seemed to be masked by a high sucrose content. © 2000 Society of Chemical Industry

Quality of carrots as affected by pre- and postharvest factors and processing

The aim of this review is to provide an update on factors contributing to quality of carrots, with special focus on the role of pre- and postharvest factors and processing. The genetic factor shows the highest impact on quality variables in carrots, causing a 7-11-fold difference between varieties in content of terpenes, β-carotene, magnesium, iron and phenolics as well as a 1-4-fold difference in falcarindiol, bitter taste and sweet taste. Climate-related factors may cause a difference of up to 20-fold for terpenes, 82% for total sugars and 30-40% for β-carotene, sweet taste and bitter taste. Organic farming in comparison with conventional farming has shown 70% higher levels for magnesium and 10% for iron. Low nitrogen fertilisation level may cause up to 100% increase in terpene content, minor increase in dry matter (+4 to +6%) and magnesium (+8%) and reduction in β-carotene content (-8 to -11%). Retail storage at room temperature causes the highest reduction in β-carotene (-70%) and ascorbic acid (-70%). Heat processing by boiling reduces shear force (-300 to -1000%) and crispiness (-67%) as well as content of phenolics (-150%), terpenes (-85%) and total carotenes (-20%) and increases the risk of furan accumulation. Sensory and chemical quality parameters of carrots are determined mainly by genetic and climate-related factors and to a minor extent by cultivation method. Retail temperature and storage atmosphere as well as heating procedure in processing have the highest impact in quality reduction.

Effects of temperature and photoperiod on sensory quality and contents of glucosinolates, flavonols and vitamin C in broccoli florets

Broccoli is grown around the world at a wide range of photoperiods and temperatures, which may influence both sensory quality and phytochemical contents. Florets produced in phytotron and at two semi-field sites (70 °N and 58 °N) were examined for effects of contrasting temperatures and photoperiods on sensory quality and contents of glucosinolates, flavonols and vitamin C. Growth conditions associated with high northern latitudes of low temperature and long photoperiods, produced bigger floral buds, and florets with sweeter taste and less colour hue than more southern conditions. The contents of vitamin C did not vary, while the response of individual glucosinolates varied with temperature and day length, and contents of quercetin and kaempferol were lower in phytotron than under semi-field conditions. Thus, our results show that contrasting temperatures and photoperiods influence the sensory quality of broccoli florets, while contents of different bioactive phytochemicals are not influenced in a unidirectional pattern.

Effects of genotype, soil type, year and fertilisation on sensory and morphological attributes of carrots (Daucus carota L.)†

BACKGROUND The aim of the study was to investigate the effects of variety, soil type and fertilisation, and the interactions between these factors, on yield and quality traits of carrots. RESULTS Optimum fertilisation levels for yield and quality of grade one roots were found to be between 80 and 160 kg ha(-1) for nitrogen and between 0 and 120 kg ha(-1) for potassium depending on soil type and precipitation. Carrots grown in peat soil had the highest score for sweetness and the lowest scores for negatively associated characteristics such as bitterness, earthy flavour, terpene flavour and firmness. Nitrate content and the amounts of splitted and forked roots were lowest on sandy soil. Variety significantly affected number of grade 1 roots, dry matter, nitrate content and most of the sensory attributes tested. Interactions between variety, soil type and nitrogen fertilisation were found for most of the tested quality characteristics. CONCLUSION The investigations showed that year and variety had the highest impact on the carrot quality attributes studied, whereas soil type and fertilisation had less influence. Peat soil and moderate fertilisation with N and K gave optimal sensory quality while sand soil gave optimal quality as regards morphological characters like splitting and forking of roots as well as nitrate content.

Quality assessment of baby food made of different pre-processed organic raw materials under industrial processing conditions

The market for processed food is rapidly growing. The industry needs methods for “processing with care” leading to high quality products in order to meet consumers’ expectations. Processing influences the quality of the finished product through various factors. In carrot baby food, these are the raw material, the pre-processing and storage treatments as well as the processing conditions. In this study, a quality assessment was performed on baby food made from different pre-processed raw materials. The experiments were carried out under industrial conditions using fresh, frozen and stored organic carrots as raw material. Statistically significant differences were found for sensory attributes among the three autoclaved puree samples (e.g. overall odour F = 90.72, p < 0.001). Samples processed from frozen carrots show increased moisture content and decrease of several chemical constituents. Biocrystallization identified changes between replications of the cooking. Pre-treatment of raw material has a significant influence on the final quality of the baby food.

Rapid analysis of 6-methoxymellein in carrots by boiling water extraction, solid phase extraction and HPLC

Abstract By modification and combination of existing methods we have developed a rapid method for quantification of 6-methoxymellein in carrot roots by means of boiling water and solid phase extraction, followed by high performance liquid chromatography (HPLC). The performance of the method was found to be acceptable, when tested by three consecutive boiling water extractions from carrot samples with different levels of 6-methoxymellein. The recovery was 96–99% after one extraction. With this method it was possible for one person to extract 20 samples during a working day and further quantify the amount of 6-methoxymellein by automatic HPLC the following night.

Multi-method comparison of carrot quality from a conventional and three organic cropping systems with increasing levels of nutrient recycling

BACKGROUND There is a need to advance the study of the effects of organic and conventional systems on product quality. In particular, little is known about the importance of different farming practices concerning nutrient cycling and the use of external inputs within organic farming for the quality characteristics of the products. In this study the quality characteristics of carrot grown under different farming practices (conventional and three organic cropping systems) over a two-year period were analysed with the aim of discriminating between organic and conventional and investigating the effect of different organic farming practices concerning nutrient recycling and use of external nutrient input. RESULTS All quality characteristics measured did not give a clear differentiation between the carrots from the different growing systems, even when multivariate statistical evaluation (principal component analysis) was applied, because of the significance of the differences between the field replicates within each management system and of the seasonality. Only some tendencies were emphasised over the two years that could be related to the fertilisation practices and the external inputs used. CONCLUSION The results indicated that it was not possible to discriminate over the years between carrots from conventional and different organic cropping systems even though controlled conditions and a multi-method approach of analysis were adopted.

Effects of Organic and Waste-Derived Fertilizers on Yield, Nitrogen and Glucosinolate Contents, and Sensory Quality of Broccoli (Brassica oleracea L. var. italica)

Organic vegetable production attempts to pursue multiple goals concerning influence on environment, production resources, and human health. In areas with limited availability of animal manure, there is a need for considering various off-farm nutrient resources for such production. Different organic and waste-derived fertilizer materials were used for broccoli production at two latitudes (58° and 67°) in Norway during two years. The fertilizer materials were applied at two rates of total N (80 and 170 kg ha(-1)) and compared with mineral fertilizer (170 kg ha(-1)) and no fertilizer. Broccoli yield was strongly influenced by fertilizer materials (algae meal < unfertilized control < sheep manure < extruded shrimp shell < anaerobically digested food waste < mineral fertilizer). Yield, but not glucosinolate content, was linearly correlated with estimated potentially plant-available N. However, extruded shrimp shell and mineral NPK fertilizer gave higher glucosinolate contents than sheep manure and no fertilizer. Sensory attributes were less affected by fertilizer material and plant-available N.

How to understand the complexity of product quality and the challenges in differentiating between organically and conventionally grown products—exemplified by fresh and heat-processed carrots (Daucus carota L.)

Quality traits are highly focused upon in the marketing of organic food products. There is a need to define and measure quality as consumers seem to have preconceived notions about the superior health value and taste of organic compared to non-organic products. A commonly held opinion among many consumer groups is that organic farming guarantees optimum quality, despite the fact that this remains unproven. The aim of this paper is to contribute to a better understanding of the complexity of quality traits in a plant-based food product, using carrots as an example. Selected designated quality aspects are presented to describe the complexity of quality and discuss the challenges of using these aspects in differentiating between organic and conventional products. The paper concludes we have insufficient tools to be able to adequately authenticate organically produced carrots. The same may be the case for most vegetables and fruit products. Suggestions for further studies include the soil and location aspect (terroir), in order to trace a product back to its origin in an organically or conventionally farmed field by finding a unique fingerprint for chemical constituents of samples.

Temperature and light conditions at different latitudes affect sensory quality of broccoli florets (Brassica oleracea L. var. italica)

BACKGROUND Broccoli (Brassica oleracea L. var. italica) is a popular vegetable grown at a wide range of latitudes. Plants were grown in 2009-2011 in pots with standardized soil, irrigation and nutrient supply under natural temperature and light conditions at four locations (42-70° N). A descriptive sensory analysis of broccoli florets was performed by a trained panel to examine any differences along the latitudinal gradient for 30 attributes within appearance, odour, taste/flavour and texture. RESULTS Average results over three summer seasons in Germany, southern Norway and northern Norway showed that the northernmost location with low temperatures and long days had highest scores for bud coarseness and uniform colour, while broccoli from the German location, with high temperatures and shorter days, had highest intensity of colour hue, whiteness, bitter taste, cabbage flavour, stale flavour and watery flavour. Results from two autumn seasons at the fourth location (42° N, Spain), with low temperatures and short days, tended toward results from the two northernmost locations, with an exception for most texture attributes. CONCLUSION Results clearly demonstrate that temperature and light conditions related to latitude and season affect the sensory quality of broccoli florets. Results may be used in marketing special quality regional or seasonal products.