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Does harvest time change globe artichoke quality?
When you cut a globe artichoke changes what is in it. On a farm near Denmark, Western Australia, late-spring heads were smaller, but more of each head was edible and it held more inulin-type fructans. Early-spring heads were bigger and richer in phenolics.
A Murdoch University-led team wanted to know how harvest time, and the weather leading up to it, changes the size, edible yield, inulin, phenolics and browning of globe artichokes, to help select better artichoke lines (Tilley et al., 2026). They cut heads from the same field population on three dates through the spring of 2023 and took them back to the lab.
What this means for your grow
In this trial, when the heads were cut changed what was in them. Heads cut in late November weighed less on average (178.5 g) than heads cut in late September (248.3 g), but on average 54.9% of a late head was edible portion, against 36.1% of an early one. The authors suggest early heads may suit eating fresh and late heads may suit processing. This was one rain-fed, organically managed farm in one spring, with a mixed population of unnamed artichoke lines, so treat it as a guide to what can change across a season rather than a picking date to copy.
What did the team do?
The artichokes grew in three fields on Mt Lindesay farm, near Denmark in Western Australia. The farm raises its artichokes from its own seed and offshoots, so there is no defined variety, and the team treated every plant as its own uncharacterised line. The plants were 2 to 3 years old, at one plant per square metre, and were grown with organic practices: no fertiliser, no weed management and no supplementary irrigation, relying mainly on rainfall.
On 25 September, 22 October and 21 November 2023 (early, mid and late spring), the team cut 18 primary heads at random, six from each field, so 54 plants in all. They measured the length and diameter of each head at harvest. Back at Murdoch University they weighed each head and its edible portion (the receptacle and the base of the inner bracts), then analysed inulin, phenolics and the browning enzyme polyphenol oxidase (PPO). Total fructans were analysed by an outside laboratory, Symbio Laboratories. They also tracked the colour of the cut surface for 90 minutes. Weather for the 28 days before each harvest (solar radiation, temperatures and chill hours) came from nearby weather stations.
What did they find?
- Size: mean head weight was 248.3 g in September, 236.2 g in October and 178.5 g in November. The November heads were significantly lighter than both earlier harvests.
- Edible portion: the edible part made up 36.1% of head weight in September, 39.8% in October and 54.9% in November. The November figure was significantly higher than both. Dry weight of the edible portion rose with each harvest, from 14.4% to 16.5% to 19.7%.
- Fructans and inulin: mean fructan content was 43.80 g kg-1 (fresh weight) in September, 59.73 g kg-1 in October and 81.16 g kg-1 in November. Inulin (chain lengths DP9 to DP23) followed the same pattern: 7.96, 10.32 and 12.70 g kg-1. Longer inulin chains increased more than shorter ones.
- The weather link: fructan and inulin went up with mean daily solar radiation and down with chill hours in the 28 days before harvest.
- Phenolics: total phenolic content was highest in September (8.67 g kg-1), then 7.16 g kg-1 in October and 6.31 g kg-1 in November. It fell as solar radiation rose.
- Browning: cut artichoke changed colour fast in the first 9 minutes. Harvest time did not change PPO activity or the overall amount of colour change, but heads with more phenolics changed colour more. Cut surfaces with more phenolics were also more yellow straight after cutting.
Across all 54 heads, fructan content in the edible part ranged from 24.59 to 119.23 g kg-1 (fresh weight), and the authors note substantial variation between individual lines.
What could it mean?
The authors conclude that harvest time and environmental conditions influence key quality attributes of globe artichokes, and that both genetics and environment contribute. They suggest early-harvest artichokes may suit fresh consumption, given their larger size, yellow edible portion and high phenolic content, while late-harvest artichokes may suit value-add processing, with their higher edible yield and dry matter and lower phenolic content. They also suggest the link between cut-surface yellowness and phenolics could one day lead to a quick in-field colour check, which still needs to be developed and validated. The study was aimed at selecting better artichoke lines for fresh eating and processing; it did not test picking dates in a home garden.
What were the limitations?
Soil composition could not be analysed, so the three fields were used as blocks to control for it. The plants were lines of unknown genetics, with substantial variation between them. Harvest time was the main factor studied, and the authors treat the weather differences as a consequence of harvest time. The paper's abstract gives the late-harvest fructan mean as 61.56 g kg-1, while its Results give 81.16 g kg-1; this post uses the Results figure. One of the phenolic peaks (a dicaffeoylquinic acid isomer) was not an exact match for the reference standard. The authors say further work is needed on why phenolics fall as solar radiation rises and on what else drives browning.
Trial details
- Where: Mt Lindesay farm, near Denmark, Western Australia, Australia, in three fields (A, B and C) used as experimental blocks. Facility type: field. Lab work at Murdoch University, Western Australia (total fructans by Symbio Laboratories).
- Who: Murdoch University (Centre for Crop and Food Innovation, Food Futures Institute, and other Murdoch schools and centres), with co-authors from Mt Lindesay.
- Crop and stage: globe artichoke (Cynara cardunculus L.); no defined variety (plants from self-propagated seed and offshoots, each treated as an uncharacterised line); plants 2 to 3 years old; primary heads cut at principal growth stages 51 to 55 of the BBCH scale.
- How long: one spring, with harvests on 25 September, 22 October and 21 November 2023.
- System: field-grown at one plant per square metre (1 m2 per plant); organic management with no fertiliser inputs, weed management or supplementary irrigation; water mainly from natural rainfall.
- Climate: daily solar radiation, maximum and minimum temperature and total chill hours for the 28 days before each harvest, from the Bureau of Meteorology and the DPIRD Quickup Dam weather station (8.7 km away) and the Denmark Agricultural School weather station (11.8 km away); rainfall recorded on site. Total chill hours were 131 h (September), 118 h (October) and 34 h (November).
- Design: 18 heads per harvest (six from each field), one primary head per plant, 54 plants in all. Measures: head length and diameter at harvest (estimated volume); in the lab, head weight, edible portion weight and dry weight; total fructans (AOAC 999.03, Symbio Laboratories); inulin chain lengths DP9 to DP23 (MALDI-MRMS); chlorogenic acid, a dicaffeoylquinic acid isomer and apigenin-7-O-glucuronide (UHPLC-ESI-MS/MS); total phenolics (Folin-Ciocalteu); PPO activity; cut-surface colour (CIE L*a*b*) from 0.5 to 90 minutes. One-way ANOVA with Tukey's HSD, multiple linear regression and Spearman correlations.
- Results: head weight 248.3 g (September), 236.2 g (October), 178.5 g (November; lower than September, p = 0.002, and October, p = 0.012); edible portion 36.1%, 39.8% and 54.9% of head weight (November higher, p < 0.001); edible portion dry weight 14.4%, 16.5% and 19.7%; fructans 43.80, 59.73 and 81.16 g kg-1 fresh weight (range 24.59 to 119.23 g kg-1); inulin (DP9 to DP23) 7.96, 10.32 and 12.70 g kg-1; total phenolics 8.67, 7.16 and 6.31 g kg-1 (September higher than October, p = 0.02, and November, p < 0.001); chlorogenic acid higher in September than November (p = 0.034); no difference between harvests in PPO activity or total colour change after cutting.
- Funding: the Future Food Systems Co-operative Research Centre (P3-008) and an Australian Government Research Training Program Scholarship. The authors declare no conflicts of interest.
- Publication: Food Science & Nutrition 14(11), e72490, published 27 October 2026, https://doi.org/10.1002/fsn3.72490. Licence: CC BY 4.0.
- Not reported in the paper: soil type and composition (not analysed), rainfall totals in the main text (they are in a supplementary figure), total yield per plant or per hectare across the season, and eating quality.
Links
- The study: Harvest Time Influences Inulin and Phenolic Accumulation of Globe Artichoke (Cynara cardunculus L.)
- The institution: Food security research, Murdoch University
References
- Tilley, A., McHenry, M. P., McHenry, J. A., Wang, Y., Shemesavar, S., Kowalczyk, M., Loo, R. L., Bayliss, K. L., & Solah, V. A. (2026). Harvest time influences inulin and phenolic accumulation of globe artichoke (Cynara cardunculus L.). Food Science & Nutrition, 14(11), e72490. https://doi.org/10.1002/fsn3.72490