Ultraviolet light treatment has been used successfully to reduce postharvest fungal decay in tomatoes, strawberries, peaches, and citrus, presumably through elevated spore death and/or increased phytoalexins. The purpose of this experiment was to determine the effectiveness of UVC light as a postharvest treatment for blueberries. `Blue Crop' and `Collins' fruit were harvested from a local grower in 2003 and 2004 and exposed to 0, 1000, 2000, and 4000 Joules of light (354 nm) supplied from 30-W germicidal bulbs. Fruit were held at 5 °C for 14 days. Application of 1000 to 2000 J UVC light reduced decay incidence by 10% compared to controls. The major decay organism was ripe rot (Collectotrichum gloeosporioides). Total phenolics, total anthocyanin, and ferric reducing absorbance power differed with variety, increased with storage, and were similar among light treatments. Firmness of non-decayed fruit was not affected by storage or treatment. Application of UVC light offers a means for reducing fungal decay in blueberries if applied at rates between 1000 and 4000 J.
Penelope Perkins-Veazie and Julie Collins
Catherine Nicolle, Gérard Simon, Edmond Rock, Pierre Amouroux and Christian Rémésy
Carrot (Daucus carota L.) is ranked among vegetables as the most consumed and the best provitamin A provider. Moreover, carrot also contains vitamins, phenolic compounds, and other antioxidant micronutrients. The influence of carrot genetic background on the content of several micronutrients was investigated. Carotenoids and vitamins (C and E) were analyzed by HPLC in 20 varieties of carrot, and antioxidant activity of carrots was investigated with colorimetric methods (ORAC and Folin-Ciocalteu). There were large differences among cultivars in carotenoid content (0.32 to 17 mg/100 g of fresh weight). In yellow and purple carrots, lutein represents nearly half of the total carotenoids. By contrast, in orange carrots, β-carotene represents the major carotenoid (65%). The concentration of vitamin E ranged from 191 to 703 μg/100 g of fresh weight, whereas the concentration in ascorbic acid ranged from 1.4 to 5.8 mg/100 g. For all these components, dark-orange carrots exhibited the highest values. Significant differences among these 20 varieties were also recorded for mineral and total phenolic compound concentrations. Purple and dark-orange carrots could be preferred to usual carrot varieties to benefit from their specific micronutrients (anthocyanins, carotenoids, or vitamin E). ORAC is a complex reflection of phytomicronutrients but is not tightly linked to vitamin C levels, as shown for white carrots, which are rich in this vitamin.
D.J. Makus and A.R. Gonzalez
Black and white plastic rowcovers were established over field-grown `Jersey Giant' asparagus (Asparagus officinalis L.). Spears were cut for 7 weeks. Season soil temperatures were lowest under white plastic and highest without plastic covering. Night air temperature under plastic covers was ≈ 1.4C higher than without plastic covering (control), but day air temperature was typically 10C higher under black plastic, with temperatures under white plastic intermediate. Marketable yield (t·ha-1) was improved with the use of plastics as was total yield (P = 0.05), but spear number/ha was similar in all treatments. There was no consistent treatment effect on spear diameter. Average spear weight was higher when under plastic, whereas spear length was reduced compared with uncovered spears. There were no differences among treatments in spear fiber content, but spears grown under plastic covers were higher in soluble solids content, titratable acidity, and nitrate and lower in protein, ascorbic acid, and total phenolics than uncovered spears. Quantitative differences in these constituents were also a function of whether they were from the upper, middle, or lower spear segment. Very little chlorophyll and carotenoids were produced in the absence of light, but there was a chroma (color intensity) difference between spears grown under the two plastics.
A. Howell, W. Kalt, J.C. Duy, C.F. Forney and J.E. McDonald
It is now widely held that the antioxidants contained in fruit and vegetables can provide protection against certain human degenerative conditions that are associated with oxygen free radical damage. This view is supported by epidemiological, in vitro, and more recently, in vivo evidence. Phenolics (polyphenolics) contribute substantially to the antioxidant complement of many small fruit species whose ripe fruit are red, purple or blue in color. Fruit containing high levels of phenolic antioxidants would be attractive to health conscious consumers, therefore optimization of production and processing factors affecting small fruit antioxidant capacity is desirable. In many small fruit crops, antioxidant activity [measured as oxygen radical absorbing capacity (ORAC)] is positively correlated with their content of anthocyanins and total phenolics. Genera, species, and genotypes vary with respect to phenolic content. Both annual and geographical factors appear to influence ORAC, although many years of study are needed to distinguish these effects from other biotic and abiotic factors that influence fruit phenolic content. Antioxidant capacity due to phenolics is decreased by food processing practices, such as heat or aeration.
Federica Galli, Douglas D. Archbold and Kirk W. Pomper
Pawpaw [Asimina triloba (L.) Dunal] has significant potential as a new fruit crop. During ripening, loss of firmness is extremely rapid, and this trait may be the biggest obstacle to the development of a broader market. Cold storage of pawpaw fruit seems limited to 4 weeks at 4 °C, though fruit softening merely slows during storage. A study of several cultivars with commercial appeal has shown that none have superior cold storage life. Extending the cold storage beyond 4 weeks resulted in increasing loss of fruit firmness, poor poststorage ripening, and development of quality traits, and many fruit exhibiting flesh and peel discoloration. Cold storage duration affected fruit volatile production. By 4 weeks of cold storage, ethyl hexanoate and ethyl octanoate were the major volatiles produced, replacing methyl hexanoate, which was the major volatile produced by ripe fruit after harvest. By 8 weeks of cold storage, volatile ester production was generally low and ethyl hexanoate became the only major volatile. This loss of volatile production was accompanied by a decrease in alcohol acetyl transferase activity. Also, during cold storage, there was an increase in total phenolic content, lipid peroxidation products, and polyphenol oxidase activity. These changes may contribute to the black discoloration that developed in fruit cold-stored for 8 weeks or more. It is apparent that cold storage alone may not be sufficient to extend the storage life of most, if not all, current pawpaw cultivars beyond 4 weeks.
Parthiban Valnaickenpalayam Kumaresan, Prakasam Velappan, Prabakar Kuppusami and Thangaraju Muthu
Carrot is a rich source of nutrients. Carrots contains carotene and lycopene, which gives bright color to the roots. The quality of the carrots was assessed based on the carotene, lycopene, and other biochemical constituents such as sugars, starch, and protein. To study the effect of various isolates of the Erwinia carotovora var. carotovora on the above biochemical constituents, the pathogens were inoculated and the contents were analyzed separately at 1, 2, 3, 4, and 5 days after inoculation. The contents of ß-carotene increased significantly due to all the three isolates of the pathogen and the Coimbatore isolate recorded highest of 36.03%. The same trend was also observed in the lycopene content, with 93.55% increase over control. The contents of total and reducing sugars were found to significantly increase due to inoculation with the pathogen. The starch content showed a decreasing trend in all the isolates tested. The maximum reduction of 62.98% was observed in the roots inoculated with Coimbatore isolate. The protein content showed a decreasing trend up to 5th day of inoculation, and further reduction of about 25.45% was recorded with Coimbatore isolate on the 5th day. The total phenol content in the roots of carrot decreased significantly, and reached the least on 5th day due to the infection by all the three isolates and the maximum reduction of 22.79% was observed in roots treated with Coimbatore isolate.
Jorge M. Fonseca, James W. Rushing, Nihal C. Rajapakse, Ronald L. Thomas and Melissa B. Riley
The purpose of this review is to promote a discussion about the potential implications of herb production in controlled environments, focusing on our recent works conducted with feverfew. Research suggests that the content of secondary metabolites in medicinal plants fluctuates with changing environmental conditions. Our studies with feverfew (Tanacetum parthenium [L.] Schultz-Bip., Asteraceae) lend support to this hypothesis. Feverfew plants exposed to different water and light conditions immediately before harvest exhibited changes in content of some secondary metabolites. The highest yield of parthenolide (PRT) was in plants that received reduced-water regimes. Phenolics concentration however, was higher in plants receiving daily watering. Light immediately before harvest enhanced accumulation of PRT, but reduced the phenolic content. Notably, PRT decreased at night whereas total phenolics decreased during the photoperiod and increased at night. PRT also increased with increased plant spacing. UV light supplementation increased PRT only in plants that had undergone water stress, whereas phenolics increased when UV was applied to continuosly watered plants. Clearly, production of medicinal plants under greenhouse conditions is a promising method for controlling levels of phytochemicals through manipulation of light and water as discussed here, and possibly other environmental factors such as temperature and daylength. However, better understanding of how the environment alter secondary metabolite levels is needed as it was revealed that manipulating the environment to favor increased accumulation of one group of phytochemicals could result in a decline of other key metabolites.
Faith J. Wyzgoski, A. Raymond Miller, Joseph C. Scheerens, Peter L. Rinaldi, Bert L. Bishop, R. Neil Reese, Mustafa Ozgen, Artemio Z. Tulio Jr., M. Monica Giusti and Joshua A. Bomser
We have developed a Nuclear Magnetic Resonance (NMR)-based approach to metabolomics research that enables the identification of bioactive compounds in crude plant extracts. For this work, we used black raspberries, which are known to contain compounds that exhibit chemopreventive activity toward oral, esophageal, and colon cancers. To ascertain bioactive components and their interrelationships, NMR results for black raspberry samples from four cultivars grown on commercial farms in Ohio were examined using principal component analysis. Multivariate analysis that included anthocyanin content (HPLC), antioxidant activity (DPPH, ABTS, FRAP), total phenolics (Folin-Ciocalteau assay), and bioactivity as measured by inhibition of colon cancer HT-29 cell line proliferation showed correlations with specific regions of NMR spectra at 400 MHz. Correlations were also observed for major and minor groupings of the black raspberry samples. Replicate black raspberry samples were examined with a 750 MHz NMR spectrometer equipped with a cryoprobe that provided a 4- to 5-fold improvement in sensitivity. In this manner, even minor bioactive components in black raspberries could be examined to determine additive and synergistic effects.
Numerous recent epidemiological studies have reconfirmed the old wisdom that consumption of fruits and vegetables play an important role in maintaining a healthy life. As a result, the role of fruits and vegetables in preventing the onset of chronic diseases is being established in the wake of epidemic-level health problems. The majority of evidence links various antioxidant phytochemicals in fruits and vegetables to the reduction in chronic diseases. Various methods are being investigated to enhance functional phytochemicals in fruits and vegetables, but, our knowledge on how these methods affect functionally important phytochemicals is relatively limited at this point. Environmental factors have been shown to affect certain phytochemicals and we are investigating if changing the spectral irradiance and composition in the growing environment can improve functional phytochemicals in food crops. In the present work, we investigated the role of irradiance on functionally important phytochemicals in selected lettuce (green and red) and tomato cultivars. Preliminary results show that in lettuce, high irradiance (500 vs. 250 μmol·m-2·s-1) increased total phenolic content, anthocyanin content, red coloration, and over all antioxidant capacity. Irradiance levels used in this study did not affect functional phytochemical levels in tomato fruit. High irradiance decreased the ß-carotene content in lettuce cultivars, but lycopene levels in tomato were not affected by irradiance.
Mark Ehlenfeldt and Ronald L. Prior
Antioxidant capacity as measured by ORAC, total phenolic, and total anthocyanin concentrations were evaluated in leaf tissue of the same 86 highbush blueberry cultivars, and ORAC and phenolic levels evaluated in leaf tissue of the same materials. Average values for ORAC, phenolics, and anthocyanins in fruit were 15.9 ORAC units (1 unit = 1 μmol Trolox Equivalent), 1.79 mg/g (gallic acid equivalents), and 0.95 mg/g (cyanidin-3-glucoside equivalents), respectively. `Rubel' had the highest ORAC values, at 31.1 units. Values for ORAC and phenolics in leaf tissue were significantly higher than fruit tissue, with mean values of 490.4 ORAC units and 44.8 mg/g in leaf tissue, respectively. No significant correlations were found between fruit ORAC and leaf ORAC, or between fruit ORAC and leaf phenolics. Investigation of ORAC values in a family of 44 `Rubel' × `Duke' seedlings showed negative epistatis for ORAC values. However, an analysis of ORAC values vs. pedigree in plants from the 86 cultivar groups suggested that, across cultivars, ORAC inheritance in generally additive.