The total levels of CNGs measured here are much lower than CNG concentrations found in European or American elderberry. In a study of European elderberries evaluated at various growing locations and altitudes found that sambunigrin levels range from 0.08 ± 0.01 to 0.77 ± 0.08 µg g-1 . 6 A nearly 10-fold difference in concentrations between elderberry samples highlights the variation on CNG levels due to differences in growing conditions and environmental factors like sun exposure and temperature fluctuations. Furthermore, evidence of CNGs degrading with thermal processing has been evaluated in European elderberry products: when sambunigrin levels were measured in raw and cooked elderberry juice and other products, heating of elderberry juice reduced the level of sambunigrin, from 18.8 ± 4.3 mg kg-1 to 10.6 ± 0.7 mg kg-1 . 1 Liqueur, tea, and spread also had significantly lower CNG concentrations as compared to the raw and cooked juice. American elderberry was evaluated for concentration of CNGs in the seeds, juice, skin, and stem of two genotypes: Ozone and Ozark.60 Elderberry juice was prepared by thawing previously frozen berries in a plastic bag and gently pressing to release juice. The juice of these elderberries contained amygdalin, dhurrin, prunasin/sambunigrin , and linamarin. Total concentrations of these four CNGs was 4.01 µg g-1 in Ozone and 3.66 µg g-1 in Ozark elderberries. The levels of amygdalin and prunasin/sambunigrin were almost equal in Ozone but in Ozark,vertical gardening in greenhouse prunasin/sambunigrin levels were much higher than amygdalin . These concentrations are much higher than the levels found in the present study, as raw blue elderberry juice had a total CNG concentration of only 0.737 µg g-1 .
Because CNGs are formed from phenylalanine, it is possible that the blue elderberry had limited stock of this key material to create CNGs. An alternative reason may be that blue elderberry may have less expression of the genes needed to form CNGs like sweet almonds compared to bitter almonds.A future study should investigate the impact of freeze thaw cycles on the activity of β-glucosidase in elderberries because elderberries are frequently frozen before processing because they can spoil quickly if only refrigerated. Two cooking temperatures were investigated to understand the impact of temperature on the degradation rates of the phenolic compounds in blue elderberry juice. The pH and soluble solids were evaluated for the five juice replicates to ensure the juices were similar for the cooking process. The average pH value of the juices was 3.76 ± 0.11 and the average Brix reading was 16.2 ± 1.1%. The major phenolic compounds in elderberry juice were measured via HPLC-DAD and include 5-hydroxyprogallol hexoside , which is a novel phenolic compound tentatively identified for the first time by Uhl et al. 202239 chlorogenic acid, rutin, isorhamnetin-3-O-glucoside, cyn 3-sam, and cyn 3-glu. Whereas levels of cyn 3-sam and cyn 3-glu decreased to 82.2 ± 6.9 % and 79.3 ± 6.3 %, respectively , more than 98% of the original concentration of 5-HPG, rutin, isorhamnetin-3-O-glucoside and chlorogenic acid remained after two hours. At the higher cooking temperature , the anthocyanins again experienced significant degradation, retaining only 33.2 ± 4.6 % and 36.8 ± 5.5 % of the original concentration after cooking two hours . In a separate study of the thermal stability of elderberry juice, 15% of cyn 3-sam and cyn 3-glu were retained in juice as compared to control juice.
Szalóki-Dorkó, et al. demonstrated that the more complexly glycosylated anthocyanins cyn 3-sam is more stable during thermal process as compared to cyn 3-glu.The results of our study are similar to Oancea et al. which showed after 90 min at 100 °C, total anthocyanin content degraded 58 %.However, that study also observed an increase in total phenolic and total flavonoid content after 60 min, followed by a gradual decrease, which was not observed herein. If sample vials were sealed well to protect from any loss of moisture, this increase in concentrations may be due to the release of phenolic compounds bound to the cell well or other polysaccharides, which can be released with the assistance of pectinase treatments.The main flavonols in blue elderberry, rutin and isorhamnetin glucoside, were stable during the thermal processing, retaining 100.5% and 99.3%, respectively, of their original concentration even at 95 °C . The high retention rates of rutin and isorhamnetin glucoside match literature reports for the thermal stability of these compounds, which show that rutin has a strong thermal stability at acidic pH. More than 80% of the starting concentration was retained after five hours of cooking at 100 °C at pH 5.148 Our results do not agree with another study in which rutin had an activation energy 107.3 kJ/mol, and the half-life values at 70 and 90 °C were 19.25 and 1.99 h, respectively; however, the rutin was in an aqueous solution at pH 6.6.Other compounds present in blue elderberry juice, in addition to a lower pH, could cause synergistic effects to improve stability of rutin in the present study. Limited information on the thermal stability of isorhamnetin glucoside was found, though a study of black currant juice stability found that during long-term storage at room temperature and at 4 °C, isorhamnetin glucoside concentrations did not change significantly during the 12-month period. In the same study, rutin did not change significantly during storageThe main phenolic acid in blue elderberry juice, chlorogenic acid, was also thermally stable.
This result was unexpected, as another study on the thermal stability of chlorogenic acid in a complex with amylose showed a significant decrease in content after 10-15 minutes, depending on the temperature.Their results also showed that a 10 °C increase in temperature results in a 2.5-fold increase in the rate of degradation of chlorogenic acid. It can be beneficial to maintain levels of chlorogenic acid in anthocyanin-rich matrices, as shown in black carrot extract where chlorogenic acid increased absorbance of cyanidin-based anthocyanins at pH 3.6 and 4.6 due to intermolecular co-pigmentation.Overall, our results show that blue elderberry juice behaves similarly to anthocyanin-rich matrices, in that longer processing at higher temperatures degrades anthocyanins. The two main anthocyanins in blue elderberry, cyn 3-sam and cyn 3-glu, behaves similarly during processing, degrading at about the same rate at 72 °C and 95 °C. Furthermore, the other major phenolic compounds like rutin, isorhamnetin, and chlorogenic acid, were highly stable and can withstand the thermal processing. Our study into the effects of thermal processing on the phenolic composition and cyanogenic glycoside content in blue elderberry juice showed that the main anthocyanins present degrade faster at higher temperatures but other important phenolic compounds like rutin and isorhamnetin 3-glucoside are more thermally stable, retaining over 90% of their original concentrations even after two hours at 95 °C. Furthermore, neoamygdalin and sambunigrin were measured in the blue elderberry juice, which were in lower concentrations compared to European and American elderberry. Perched in the hills above Monterey Bay, the UC Santa Cruz campus looks out on the rich farmland of the Pajaro and Salinas Valleys, home to some of the most successful and productive organic farming operations in the country. UCSC’s own 25-acre farm, managed by the Center for Agroecology and Sustainable Food Systems, has been training organic farmers for nearly four decades. Yet until a year ago, students eating in the campus dining halls seldom had a choice of organically grown food. Today, all five UCSC dining halls and the University Center’s Terra Fresca restaurant serve certified organic produce every day of the week. Growers from the seven local farms that make up the Monterey Bay Organic Farmers Consortium —including UCSC’s farm—pool their produce through the Agriculture and Land-Based Training Association in Salinas to sell to UCSC Dining Services. ALBA’s contract to provide locally grown organic produce is a first among the UC system’s 10 campuses. This transition didn’t come easily. It’s the result of several years of collaboration and hard work by students, staff, and local growers, as well as some fortuitous timing. Thanks to these efforts, UCSC is now positioned to be a national model for a growing movement called “farm-to-college,” which, like the K-12 farm-to-school movement, is bringing fresh,greenhouse vertical farming local produce to student dining halls through direct relationships between farmers and educational institutions. Farm-to-school or farm-to-college arrangements help farmers get more of the food dollar, benefit local economies, and give students access to locally produced, fresh food. Several features distinguish UCSC’s Farm-to-College project: a consortium of organic growers was formed to supply produce to the campus dining halls; sustainable food purchasing guidelines were developed; and education is incorporated from the campus farm fields to the dining halls.
In this article we’ll discuss the history of the farm-to-college work at UCSC, describe some of the strategies and obstacles involved in changing the University’s purchasing practices, and report reactions from participating farmers and campus chefs. We’ll also talk about the key role that students across the UC system are now playing in a campaign to create sustainable food systems at all of UC’s campuses, and offer advice on how other campuses can implement such efforts.In the winter of 2003, UCSC’s Students for Organic Solutions brought together diverse stakeholders of the campus food system at the annual Campus Earth Summit to discuss how to create sustainable change in the system, including the advantages of purchasing organic produce from local farmers. This grassroots effort was largely unsuccessful in garnering support from Sodexho—the largest food and facilities management services company in North America—which was then under contract to provide all the food to UCSC campus dining halls. Sodexho was at the same time dealing with its own challenges. UCSC’s Students for Labor Solidarity—unhappy with the company’s labor practices—had organized to “dump Sodexho” in conjunction with campus labor unions. After a six-month student campaign the UCSC administration ended its 30-year contract with the company in June 2004, enabling Dining Services to contract directly with suppliers for the first time. This transition to an “in-house” service structure opened a crucial avenue to work with the university administration in designing a more sustainable food system. Early in this process, conversations between members of the Center for Agroecology and Sustainable Food Systems and Dining Services director Alma Sifuentes brought staff of Dining Services to the UCSC Farm, an important step in introducing the concept of sustainability to the campus food system. Sifuentes also helped catalyze the effort to bring organic, Fair Trade coffee to campus through the Community Agroecology Network .Several months of meetings followed the 2004 Earth Summit as members of campus and community organizations came together as the Food Systems Working Group to craft the details of a purchasing guidelines proposal. Included were representatives from the Center for Agroecology and Sustainable Food Systems, Community Alliance with Family Farmers, Comercio Justo, the Community Agroecology Network , Students for Organic Solutions, and the Education for Sustainable Living Program —all of whom brought expertise in various aspects of sustainable agriculture and food systems. Under these guidelines, preference is given to price-competitive bids from the primary food vendor that meets the greatest number of criteria. For the local organic contract, all produce must be grown within 250 miles of Santa Cruz and be certified organic. In selecting a local organic produce vendor, preference is given to price competitive bids that are “worker supportive” as defined in the guidelines. In May 2004, the Food Systems Working Group formally presented these guidelines to UCSC’s Dining Services. Students for Organic Solutions also continued to build support for bringing local organic food to the dining halls by putting on educational classroom presentations and organic “taste tests” for students. Timed to coincide with the presentation of the guidelines, a campaign spearheaded by Comercio Justo and CAN generated over 2,000 postcards from students to Dining Services in support of the guidelines’ adoption. Honoring the guidelines, Dining Services selected the local distributing company Ledyard as the prime food vendor in 2004. The sole source organic produce contract with the Monterey Bay Organic Farming Consortium began in late summer 2005 after a year-long struggle to find a way to include “worker supportive” as a criterion in selecting a vendor. During the process, FSWG found that “worker supportive” could not be used as a criterion under UC purchasing regulations because, unlike organic and local, employment practices are not regarded as a characteristic of food. In order to qualify for a sole source contract, local organic farmers formed a consortium and agreed to make their farms available for organic farming and food system research conducted under the auspices of the Center.