White Spears Research Articles

Elucidating the flavour of cooked white asparagus by combining metabolomics and taste panel analysis

A typical feature of cooked white spears of Asparagus officinalis is their specific flavour. This has been the focus of several recent instrumental and panel studies. Few of these report on the comparison of raw and cooked materials which may lead to a deeper understanding of the flavour chemistry and compositional shifts occurring during food preparation. Here, solid-phase microextraction GC-MS and LC-MS analyses of raw and cooked spears were performed to profile asparagus metabolites. A taste panel evaluated flavour attributes of the same materials. Unsupervised and supervised statistical approaches were applied to investigate the profiles and link metabolomics and sensory results. Flavonoids, saponins and medium-chain volatile carbonyls were more abundant in the raw spears while sulphur-containing volatile compounds, oxidized fatty acids and phenolic acids were more abundant in the cooked spears. GC-Olfactometry-MS was also performed and revealed 35 odour-active volatile flavour compounds. We have proposed and discussed the key biochemical pathways and chemical transformations relevant to asparagus ‘flavour’.

Investigation of sulfur-containing compounds in spears of green and white Asparagus officinalis through LC-MS and HS-GC–MS

Asparagus officinalis is largely consumed as food in many parts of the world, and due to its content in secondary metabolites can be considered as a vegetable with health-promoting value. Part of its organoleptic qualities can be ascribed to the presence of sulfur-containing compounds, nevertheless qualitative data about the volatile and non-volatile pools of these compounds in green and white spears of asparagus are poorly investigated. Due to the wide alimentary use of this crop and the potential biological properties of S-containing compounds, research aimed at filling this gap is required. In this paper, a comprehensive characterization of S-metabolites in asparagus performed by LC-MS and GC–MS is reported. Both green and white varieties of asparagus were considered. The fresh vegetal material was subjected to different sample preparation procedures, such as solvent extraction, distillation, and headspace sampling. Furthermore, a derivatization protocol with 4,4′-dithiodipyridine was used for low-molecular weight thiols, and both derivatized and underivatized compounds were analysed by LC-MS. The methods allowed to identify 80 S-containing metabolites in asparagus samples, and to assess the distribution of these compounds in different parts of the spears. Results were discussed comparing the literature, and the identified compounds were considered to explain some peculiar taste and odorous properties of green and white asparagus, although further research is required to confirm our hypotheses.Overall, in this work we report for the first time an exhaustive characterization of S-compounds profile in spears of green and white Asparagus varieties. Furthermore, results indicate that multiple approaches should be used to study the S-containing metabolites of this plant, due to their diverse chemical properties.

The occurrence of Fusarium species in white spears of Asparagus officinalis

The aim of the study was to determine the species composition of fungi of the Fusarium genus found on white Asparagus officinalis spears, depending on the presence or absence of disease symptoms, age of the plantation, date of harvest and the place from which samples were collected for mycological analysis. Additionally, the pathogenicity of selected Fusarium spp. isolates was determined. A. officinalis L. was cultivated for white spears. The research was conducted on the German dioecious cultivar ‘Eposs’. Samples of A. officinalis spears for tests were collected from two plantations. Six species of fungi of the Fusarium genus were identified in the asparagus spears: F. culmorum, F. equiseti, F. oxysporum, F. proliferatum, F. solani, and F. fujikuroi. Among the Fusarium species colonizing Asparagus officinalis the greatest threat is F. oxysporum. Always there are more isolates in the spears with the symptoms, in epidermis. The late harvest date favors the development of fusariosis. This means that the spears harvested at the latest date (late June) are the most heavily colonised by fungi. The isolates of fungi of the Fusarium genus collected from the spears exhibit pathogenicity against A. officinalis plants.

Metabolomics Reveals Heterogeneity in the Chemical Composition of Green and White Spears of Asparagus (A. officinalis).

Green and white asparagus are quite different crops but can be harvested from the same plant. They have distinct morphological differences due to their mode of cultivation and they are characterised by having contrasting appearance and flavour. Significant chemical differences are therefore expected. Spears from three varieties of both green and white forms, harvested in two consecutive seasons were analysed using headspace GC-MS and LC-MS with an untargeted metabolomic workflow. Mainly C5 and C8 alcohols and aldehydes, and phenolic compounds were more abundant in green spears, whereas benzenoids, monoterpenes, unsaturated aldehydes and steroidal saponins were more abundant in white ones. Previously reported key asparagus volatiles and non-volatiles were detected at similar or not significantly different levels in the two asparagus types. Spatial metabolomics revealed also that many volatiles with known positive aroma attributes were significantly more abundant in the upper parts of the spears and showed a decreasing trend towards the base. These findings provide valuable insights into the metabolome of raw asparagus, the contrasts between green and white spears as well as the different chemical distributions along the stem.

Concentrations of some chemical components in white asparagus spears depending on the cultivar and post-harvest irrigation treatments

Abstract The effect of post-harvest irrigation and genotype on the quality components of white asparagus spears was investigated. The field experiment was conducted in 2003-2008 on a very light soil in the Bydgoszcz region. The research was based on a two-factorial split-plot design with randomly selected sub-main blocks. The first studied factor was irrigation applied as two treatments: drip irrigation and microsprinkler irrigation. Non-irrigated plants were tested as the control. The second factor considered was genotype represented by three male cultivars of the garden asparagus: ‘Gijnlim’, ‘Ramos’ and ‘Vulkan’. The irrigation started after the harvest of the spears, while the concentrations of chemical ingredients were measured in the white spears collected in the next growing period. The level of the tested components was significantly influenced by both factors studied. The average amounts of dry matter, potassium, iron and nitrates measured in the white spears were 6.37%, 268.9 mg 100 g−1 f.m., 0.29 mg 100 g−1 f.m. and 62.1 mg kg−1 f.m., respectively. Compared to the control, both irrigation treatments considerably increased the dry matter and potassium contents. The irrigation reduced the amount of nitrates, although the microsprinkler irrigation gave better results than the drip irrigation. The highest concentrations of potassium and iron were measured in the spears of ‘Ramos’, especially in the case of drip-irrigated (potassium) and non-irrigated (iron) plants. The amount of dry matter was high in the spears of ‘Ramos’, while ‘Vulkan’ presented a low tendency to accumulate nitrates.

Effects of Long-term Storage of One-year-old Rootstocks in Snow Mound on the Sugar Contents of Storage Roots and White Spear Yield of Asparagus

The possibility of summer harvest of white spears from asparagus (Asparagus officinalis L.) rootstocks stored in snow cover or a snow mound was examined over two seasons, in 2008–2009 and 2009–2010 experiments, respectively. One-year-old rootstocks were dug up on November 6 and November 12 in 2008 and 2009, respectively. Medium-sized rootstocks were put into the soil in containers and stored under natural snow cover or a snow mound for about 7 months. After snow storage, sugar content of the storage root was measured and containers with rootstocks were transferred to a dark room at 20°C to examine white spear yield. Rootstocks were stably stored at 0–1°C when they were fully covered with an adequate amount of snow. In both years, the total sugar contents in storage roots of rootstocks tended to decrease as the storage duration increased. Spear yield in summer harvest after more than 6 months of storage under snow tended to be lower than in winter harvest after 0 or 1.5 months of storage. Total sugar contents in storage roots during storage might greatly affect the spear yield of rootstocks. The marketable spear yield from one-year-old rootstocks with about 900 g fresh weight stored for more than 6.5 months under a snow mound was more than 190 g per rootstock in both years. Such a spear yield suggests that white asparagus spears can be commercially produced in summer from one-year-old rootstocks stored under a snow mound, a simple and low carbon system.

EVOLUTION OF BIO-ACTIVE SUBSTANCES IN ASPARAGUS AS AFFECTED BY DIFFERENT HARVEST TIMES

In our trials at the experimental farm Pallag of Debrecen University 3 asparagus varieties ( Cumulus, Gijnlim, Grolim ) were tested on brown humus sand soil in ridge cultivation. Solids, nutritional fibre, protein, sugar and vitamin-C contents were measured in the white spears at 3 different harvest times (8 May, 24 May, 6 June 2012). Mineral element tests included B, Ca, Cu, Fe, K, Mg, Na, P, S, Zn and sulphate sulphur. Our trials confirmed the strong negative correlation (r = -0.828) between the sugar and vitamin-C content of the spears. In our variety comparison trial the variety Cumulus had the highest solids (7.1 %), nutritional fibre (4.7 %), protein (2.81 %) and sugar (3.51 %) contents. Among the microelements the high Fe content (4.93 – 7.63 mg/kg) deserves attention. Fe is variety dependent. The highest value was found in Gijnlim with 7.5 mg/kg. The sulphate-S content is responsible for the special taste and flavour of asparagus. In our trials Cumulus had the highest sulphate-S value (279 mg/kg). Cumulus also excelled in Mg content (84.10 mg/kg) and Grolim in Ca content (27,23 mg/kg). The low Na content of the element composition is essentially favourable. It varied between 17.07 and 27.23 mg/kg in the tested 3 varieties.

Effects of Various Asparagus Production Methods on Rutin and Protodioscin Contents in Spears and Cladophylls

The purpose of this study was to clarify the relationship between various cultivation conditions and the amounts of the rutin (RT) and protodioscin (PD) in asparagus spears. Green and white spears were grown in open culture and under two different blanching conditions. Although RT was detected only in the green spears, PD was detected mainly in white spears produced by covering with soil. The RT and PD contents of cladophylls grown in an open field and in a closed cultivation system were also investigated, and the closed system resulted in cladophylls with low RT and high PD, unlike the open field.

Comparison of asparagus (Asparagus officinalis L.) cultivars and the effect of covering beds

Five hybrid cultivars ('Boonlim', 'Cipres', 'Dariana', 'Franklim' in 'Steline') of white asparagus were tested on 4 locations in Slovenia (Celje, Logarovci, Nova Gorica and Novo mesto). The plantations were 7 years old when some of the raised beds were covered with black PE mulch and the yield was compared to the yield of uncovered beds. The planting space was 2.2 m between rows and 0.33 m between crowns in the row. Each cultivar had 2 covered and 2 uncovered repetitions with 15 plants (11 m2). The yield and number of spears were measured. For 6 days, white spears were divided into 4 groups based on their thickness (4-8 mm; 8-12 mm; 12-16 mm; over 16 mm), counted and weighed in order to determine the proportion and quality of marketable yield. 'Steline' (3.44 t/ha) had the lowest average yield and 'Boonlim' (6.78 t/ha), which was the best performing cultivar in Logarovci and Nova Gorica, the best. In Novo mesto there were no significant differences among cultivars and in Celje, earlier cultivars 'Franklim', 'Cipres' and 'Dariana' performed better. 'Franklim' had more spears on average but the weight of the spears was best with 'Boonlim' (46.24 g) and worst with 'Steline' (32.03 g). The mulch influenced the yield, which was 5.27 t/ha on uncovered beds and 6.25 t/ha on covered ones. It also influenced the average weight of spears, which increased from 38.15 g to 40.88 g. The mulch did not increase either the number of spears or their thickness.

Cell wall phenolics of white and green asparagus

AbstractCinnamic acids influence physical and textural attributes of plant foods as they play an important role in lignification and cross‐linking of cell‐wall polymers. Several trans‐cinnamic acids have been detected in asparagus cell wall (CW), and, of these, amounts of ferulic acid (FA) and its dehydrodimers have been found to increase significantly during post‐harvest storage. The distribution of these compounds along the different sections of white and green spears, as well as their modifications during postharvest storage, has been investigated. It has been observed that the cell walls from the apical, middle and lower sections of the green spears contain equivalent amounts of FA derivatives (about 400 µg g−1 CW), while these compounds are mainly located in the middle (681 µg g−1 CW) and lower section (975 µg g−1 CW) of the white ones. During asparagus post‐harvest storage a general increase of FA monomers and dimers took place that affected every section of both green and white spears. Major changes occurred in the middle and lower sections of the white asparagus, where the amounts of ferulic derivatives increased to 1700 and 1678 µg g−1 CW after storage. A similar but less pronounced trend was observed for the green spears. Copyright © 2005 Society of Chemical Industry

Mechanical properties of white and green asparagus: changes related to modifications of cell wall components

AbstractThe changes of texture that take place in white and green asparagus during storage and cooking are, in large part, determined by the composition and structure of the cell walls. Several instrumental methods have been applied to three sections of the spears to investigate the physico‐chemical properties that contribute to the values of texture. Cutting the spears with a razor blade is the most appropriate method for quantifying and comparing the texture of white and green asparagus and, among the different parameters that can be calculated from the curves registered during asparagus cutting, strength and toughness have been used for determining changes of texture. Post‐harvest storage caused an increase of texture mainly located in the lower portions of the white spears. The process of toughening also affected the lower section of the green spears, but to a lesser extent. Cooking resulted in a softening, mostly in the apical section of the stem. Additional information about the physico‐chemical properties of different plant tissues has been obtained by applying a tensile test to the internal and external tissues separated from asparagus sections. Copyright © 2004 Society of Chemical Industry

Comparison of textural and compositional attributes of green and white asparagus produced under commercial conditions

A textural and compositional comparison of green and white asparagus (Asparagus officinalis L., cv. ‘Grande’) produced under commercial conditions was carried out during a 60-day harvest season in 1999. Spears harvested on the 28th, 35th and 42nd day were separated into upper (tip) and lower (base) halves and analyzed for fibrousness and composition. The white spears were more fibrous, contained more nitrates, less ascorbic acid and total soluble phenols and had a lower pH than the green spears. Greater differences between tip and base in fibrousness and composition were observed in the green spears than in the white ones. Regardless of color, the spear tip had a higher pH and titratable acidity and contained more ascorbic acid, soluble solids and total soluble phenols and less fiber and nitrates than did the base.

Soil Heating Techniques for Forcing Outdoor White Asparagus into Production

ABSTRACT Hot water was circulated in two pipes placed above (AC), beside (BC), and under (UC) the crowns of the asparagus (Asparagus officinalis L.) hybrid cvs. ‘Dariana’, ‘Larac’ and ‘Steline’ to force them into production in winter. An unheated bed of each cultivar was used as control. Raised beds were covered with black plastic mulch to ensure white spears and weed control. The heating system was activated in mid-January for the 1998 harvesting season, mid-December 1998 for the 1999 harvesting season and early January for the 2000 harvesting season. In 1998 and 2000 harvesting seasons, early yield of A grade spears in the UC treatment was significantly different from controls, and the AC and BC treatments which were similar. The total yield of the UC treatment was significantly different from the control and the AC and BC treatments only in 1998. The UC treatment improved the quality of the product in 1998 and 1999 since “B” grade yield, as a percentage of “A” grade yield, appeared to be lowest. ‘Daria...

TEXTURAL AND COMPOSITIONAL CHANGES OF GREEN AND WHITE ASPARAGUS SPEARS DURING STORAGE

A textural and compositional comparison of green and white asparagus (Asparagus officinalis L. cv. 'Grande') during storage was carried out. Spears harvested from a commercial plantation on the 28th, 35th and 42nd day during the 60-day harvest season of 1999 were stored for 6 days at 1 or 10 oC. The changes in fibre content of the white spears were larger than those of the green ones, indicating that postharvest textural changes proceed more rapidly in the former and therefore the spears become tougher than those of green asparagus. The postharvest colour changes after storage at 1 oC include the appearance of an intense purple colour at the tip of the white spears, due to anthocyanin synthesis and the degradation of chlorophyll at the tip of green spears. The losses of ascorbic acid during storage were larger in the green spears, especially at the higher storage temperature. A decrease in the total soluble phenols was observed only in the green spears. The green spears were susceptible to negative geotropic growth curvature or bending, especially when the spears were placed horizontally at 10 oC. No geotropic response was observed in the white spears.

EFFECT OF THE HEATING TECHNIQUE ON EARLINESS AND TOTAL YIELD OF THREE ASPARAGUS CULTIVARS GROWN IN A HIGH TUNNEL

The purpose of this study was to investigate the efficacy of different heating techniques applied to raised beds, where the asparagus spears were grown. A central heating system burning peach stones was used to provide heating to the raised beds of three hybrid cultivars, Dariana, Larac and Steline, in a greenhouse, considered as a high tunnel. The hot water was circulating in two pipes placed in three different positions in terms of the asparagus crowns as follows: Above the crowns (AC), a pipe at each side of the crown (SC), and under the crowns (UC). An unheated bed of each cultivar was used as control. Raised beds were covered with black plastic mulch to ensure white spears and weed control. The heating system was activated in mid January 1998 for the first harvest period and in mid December of the same year (1998) for the second harvest period. In both harvest periods mean early yield of asparagus spears in the UC treatment was significantly higher compared with the control and the AC and SC treatments, which were similar. In the first period, total yield of all cultivars was similar under any applied heating treatment but significantly higher compared to the control. In the second period, only the total yield of the AC and SC heating treatments were significantly higher compared to the control. In the first period, cvs Dariana and Steline produced significantly earlier yield than Larac and in the second, the range of cultivars in terms of early yield was Steline, Larac and Dariana, respectively. Concerning the total yield of cultivars in both periods, Dariana yielded significantly more than the other two cultivars.

TEXTURAL QUALITY OF GREEN AND WHITE ASPARAGUS

ABSTRACTA textural comparison between green and white asparagus was conducted on three cultivars (‘Jersey Gem’, ‘Jersey General’, and ‘Jersey Giant’) harvested during spring and summer of 1990. Spears were analyzed for fibrousness and sensory characteristics at three different sections: tip, middle and base. Fibrousness of both green and white asparagus was greater in the spring. On the other hand, white spears were more fibrous than green ones. Sensory assessment of spear hardness revealed that tip and middle sections of white spears were harder than equivalent sections of green spears. Concurrently, sensory fibrousness was greater in white than in green spears and decreased from tip to base. No measurement of texture was affected by cultivar. Light microscopy did not reveal differences between green and white asparagus. However, regardless of type, the number of lignified tracheal elements within vascular bundles increased basipetally along the stem, explaining the difference among sections of spear.

ELONGACION DIARIA Y ALTURA DE APERTURA DE LA CABEZA DE LOS TURIONES DE VEINTIOCHO GENOTIPOS DE ESPARRAGO

During the 1992, 1993, and 1994 harvest seasons, the daily spear elongation of 28 asparagus genotypes was measured. Together with these measurements the degree of opening of the head of the spears was evaluated, determining, through a regression analysis, the height at which the head of the spears would start opening. There were important differences between genotypes. The most cultivated in Chile (UC 157 and UC 72), opened their heads at higher heights than others that were created for harvesting white spears, such as Aneto, Cito, Larac, and Argenteuil. Daily average elongations were of 5.58 cm at 15.5 °C, of 7.41 cm at 16.6 °C and of 7.73 cm at 19.8 °C of daily mean temperature. A raise in the mean temperature traduced itself in a greater daily elongation and in a higher total yield, but in a lower height at which the heads of the spears started to open.

Response in Green and White Asparagus to Supplemental Nitrogen and Harvest Date

`Jersey Giant' asparagus (Asparagus officinalis L.), grown in an Enders silt loam mineral soil, was given 80 kg supplemental N/ha either before or after the harvest season. Neither N application timing affected spear yield, objective color, or pigment concentration. Early supplemental N application decreased K concentration in white spears and Ca concentration in green spears. Green asparagus contained higher total-N, K, P, S, Ca, Mg, Fe, Zn, Al, Mn, and Cu concentrations but a lower soluble solids concentration (SSC) and NO3 than did white asparagus. As the cutting season progressed, spear SSC and S, Ca, NO3 (NO3 in white spears only), Zn, Mn, and Cu (Cu in white spears only) concentrations decreased, but spear K and Al (Al in white spears only) increased on a dry-weight basis. Fall residual soil NO3 levels were not affected by N application timing, but organic matter (percent) was lower in soil that received early supplemental N.

Mineral Nutrient Composition of Green and White Asparagus Spears

Mineral nutrients were determined in green and white `Jersey Giant' asparagus (Asparagus officinalis L.) spears grown in 1991 near Booneville, Ark. Green spears had higher concentrations of tissue N, K, P, S, Na, and Zn; similar levels of Fe, Al, and Cu; and lower levels of NO3 than white spears grown under opaque plastic rowcovers or under sawdust mulch. Levels of Ca, Mg, and Mn were higher in plastic-grown white spears than in those grown in sawdust. The spear tip contained higher concentrations of K, S, and Cu than the butt. Less NO3, Fe, and Al were in the tip than in the butt. Spear distribution gradients for K, Fe, and Cu were linear, whereas S and NO3 gradients were both linear and quadratic. Nitrogen, P, Ca, Mg, Zn, Al, and Mn levels were influenced by spear production method and spear segment.

Freeze avoidance in green and white asparagus spears

Previous studies have indicated that white asparagus ( Asparagus officinalis L.) spears grown under black plastic mulch tended to incur less freeze damage than green spears grown without cover. The objectives of our study were to determine whether ice-nucleation active (INA) bacteria limit supercooling of asparagus spears and whether the apparent greater freeze survival of white asparagus spears, compared with green spears, was primarily due to differences in supercooling or minimum exposure temperature. Freezing of detached green and white asparagus spears in a low temperature chamber occurred at −5.7° C and −6.6° C, respectively, averaged over three harvest dates in both 1991 and 1992. Freezing temperature differences were significant ( P = 0.06) only on 17 April 1991, with green spears freezing 3.8°C higher than white spears. INA bacteria averaged 2.9 × 10 3 cells g −1 fresh weight on green spears and were not detected on white spears on 17 April 1991. Mean INA bacterial populations were less than 2.3 × 10 2 cells g −1 fresh weight on white spears on all harvests and on five of six harvest dates from green spears. Monitoring spear temperatures in the field during a natural freeze to −9.0° C on 10 March 1992 indicated freezing temperatures from −3° C to −5° C. No emerged spears survived this exposure. Minimum air temperatures were about 2°C colder in uncovered rows, compared with covered rows. A subsequent freeze to −4.7° C on 23 March 1992 resulted in 0% and 52% surviving green and white asparagus spears, respectively. Asparagus spears exhibited a moderate potential to avoid freezing by supercooling that was greater under laboratory conditions than in the field. Degree of survival appeared to be due primarily to differences in minimum temperature and freeze duration under plastic covered and uncovered rows, rather than differences in supercooling capacity.