Effect of Sample Preparation Method on Birch (<i>Betula</i> <i>pendula</i> Roth) Leaf Phenolics

Keinänen, Markku; Julkunen‐Tiitto, Riitta

doi:10.1021/jf960168x

Cited by 63 publications

(55 citation statements)

References 11 publications

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“…The drying method did not dramatically change the relative phenolic profile of birch (Betula pendula Roth) leaf, but the ethanol extraction of fresh plant best preserved the phenolic concentration of the crude plant (Keinanen and Julkunen, 1996). Of the various drying methods tested, freeze-drying of a slowly frozen (as opposed to flash-frozen) leaf preserved most of the phenolics.…”

Section: Polyphenolsmentioning

confidence: 99%

The effect of freeze‐drying and its implications for botanical medicine: a review

Abascal

Ganora

Yarnell

2005

Phytotherapy Research

174

102

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Botanical samples are often freeze-dried (lyophilized) for use in research studies, and a variety of freeze-dried botanicals are marketed to the public. In both instances, there is an underlying assumption that freeze-drying properly preserves the medicinal qualities of plants, and is superior to other preservation methods. In fact, little systematic research has been done to verify this assumption. A review of the existing research, done primarily by the food and spice industry, indicates that freeze-drying has unanticipated and significant effects on the constituent profiles of medicinal plants that puts into question whether freeze-drying necessarily is the best method to preserve botanical medicines. This research review finds there is insufficient information to conclude that freeze-drying has negative effects on the medicinal qualities of plants. But, because existing research indicates that freeze-drying imperfectly preserves important classes of medicinal compounds (such as volatiles, phenolics and carotenoids), may increase the mutation rate in unicellular organisms and may diminish some medicinal plant actions, researchers and practitioners should carefully consider how the use of freeze-dried material may affect pharmacological and clinical study results.

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Section: Polyphenolsmentioning

confidence: 99%

The effect of freeze‐drying and its implications for botanical medicine: a review

Abascal

Ganora

Yarnell

2005

Phytotherapy Research

174

102

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“…In another study, Keinanen and Julkunen-Tiitto showed that quantity of phenolic compounds extracted from birch leaves (Betula pendula Roth) were affected by the sample drying procedure. 40 The authors compared the influence of eight different sample drying conditions (air drying at ambient temperature, oven-drying at 40 • C, oven-drying at 80 • C, freezedrying after pre-freezing samples with liquid N 2 , freeze-drying after pre-freezing samples at −18 • C, freeze-drying without pre-freezing samples, storing frozen samples for 12 days without drying, and immediate extraction of fresh samples) on extraction of phenolic compounds from birch leaves. The authors recommended that for quantitative analysis samples should be immediately analyzed after collection.…”

Section: Sample Preparationmentioning

confidence: 99%

“…The authors recommended that for quantitative analysis samples should be immediately analyzed after collection. Among the drying procedures, highest concentrations of phenolics were obtained with freeze-drying samples after pre-freezing at −18 • C. 40 Malovana et al compared liquid-liquid extraction with solid-phase extraction of phenolic compounds from wine samples. 41 The authors observed that sample preparation with liquid-liquid extraction using diethyl ether as extraction solvent at pH 2.0 provided optimum extraction yields of the phenolic compounds.…”

Section: Sample Preparationmentioning

confidence: 99%

Significance of sample preparation in developing analytical methodologies for accurate estimation of bioactive compounds in functional foods

Luthria

2006

J Sci Food Agric

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Functional foods are defined as foods or food components that provide health benefits beyond basic nutrition (for the intended population). Increased interest in bioactive food components and phytochemicals has arisen from numerous epidemiological studies that suggest that certain phytochemicals can reduce risk of chronic diseases. Sales of functional foods containing high concentrations of bioactive components have increased dramatically during the past two decades. This paper illustrates with examples the significance of sample preparation in developing analytical methodologies for accurate estimation of potentially bioactive compounds present in functional foods using phenolic phytochemicals as model substrates. The primary three steps in any analysis are sampling, sample preservation, and sample preparation. These three initial steps are often overlooked and considered 'as a means to an end' and are often not well documented in the published literature. This paper outlines a systematic protocol for optimizing extraction of phytochemicals from different plant matrices. Accurate analysis of bioactive compounds is critical for their precise and reproducible quantification in different foods, establishing appropriate dietary intake and safety guidelines, and understanding their role in human health and nutrition.

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“…The drying at low temperatures protects against the degradation of the active constituents, but it is slow and metabolic processes may continue longer, which may lead to quality loss of the aromatic plants and subsequently of the produced added value products (Keinänen & Julkunen-Tiitto 1996). Many drying methods such as convection oven drying, freeze-drying, microwave drying etc.…”

mentioning

confidence: 99%

Effect of drying method on the phenolic content and antioxidant capacity of spearmint

Orphanides¹,

Goulas²,

Gekas³

2013

Czech J. Food Sci.

120

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Orphanides A., Goulas V., Gekas V. (2013): Effect of drying method on the phenolic content and antioxidant capacity of spearmint. Czech J. Food Sci., 31: 509-513.The changes in total phenolics, hydroxycinammic acid derivatives, and antioxidant properties of spearmint after five drying treatments (convection oven drying, freeze-drying, microwave drying, and air drying with the sun exposure and without the sun exposure) were investigated. Phenolic composition of dried spearmint was analysed by spectrophotometric assays, while DPPH radical scavenging activity and Ferric reducing/Antioxidant power (FRAP) assay was used to measure the antioxidant properties. The results showed that freeze drying produced dried spearmint that had the highest total phenolics (34.6 ± 1.9 mg/g) content and the most potent antioxidant capacity (126.2 ± 0.4 mg/g for FRAP and 88.1 ± 5.9 mg/g for DPPH, respectively). On the other hand, spearmint that was dried by convection oven and microwave drying presented the lowest amount of phenolic compounds (12.0 ± 0.5 mg/g) and antioxidant potency (49.3 ± 0.7 mg/g for FRAP and 26.9 ± 1.6 mg/g for DPPH, respectively). This might be attributed to the fact that heat-sensitive phenolics were degraded or biotransformed at high temperatures. The loss of phenolic compounds and antioxidant activity reached up to 60% compared to freeze drying.

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Effect of Sample Preparation Method on Birch (Betula pendula Roth) Leaf Phenolics

Cited by 63 publications

References 11 publications

The effect of freeze‐drying and its implications for botanical medicine: a review

The effect of freeze‐drying and its implications for botanical medicine: a review

Significance of sample preparation in developing analytical methodologies for accurate estimation of bioactive compounds in functional foods

Effect of drying method on the phenolic content and antioxidant capacity of spearmint

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