Effect of vacuum freeze drying and hot air drying on dried mulberry fruit quality

Wang, Li; Wen, Haichao; Yang, N. C.; Li, Hongjiao

doi:10.1371/journal.pone.0283303

Cited by 12 publications

(3 citation statements)

References 49 publications

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“…The freeze−dried samples had significantly higher levels of fatty acids compared to the air−dried samples. Freeze drying is more effective in preserving the nutritional content and functional components of fruits compared to air drying [ 52 ]. Freeze drying retains more fatty acids in fruits compared to air drying.…”

Section: Resultsmentioning

confidence: 99%

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze− and Air−Dried New Zealand Apricots

Liu,

Oey,

Leong

et al. 2024

Foods

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Pulsed electric field (PEF) pretreatment has been shown to improve the quality of dried fruits in terms of antioxidant activity and bioactive compounds. In this study, apricots were pretreated with PEF at different field strengths (0.7 kV/cm; 1.2 kV/cm and 1.8 kv/cm) at a frequency of 50 Hz, and electric pulses coming in every 20 µs for 30 s, prior to freeze−drying and air−drying treatments. PEF treatments were carried out at different field strengths. The impact of different pretreatments on the quality of dried apricot was determined in terms of physical properties, antioxidant activity, total phenolic content, and metabolite profile. PEF pretreatments significantly (p < 0.05) increased firmness of all the air−dried samples the most by 4–7−fold and most freeze−dried apricot samples (44.2% to 98.64%) compared to the control group. However, PEF treatment at 1.2 kV/cm did not have any effect on hardness of the freeze−dried sample. The moisture content and water activity of freeze−dried samples were found to be significantly lower than those of air−dried samples. Scanning electron microscopy results revealed that air drying caused the loss of fruit structure due to significant moisture loss, while freeze drying preserved the honeycomb structure of the apricot flesh, with increased pore sizes observed at higher PEF intensities. PEF pretreatment also significantly increased the antioxidant activity and total phenol content of both air−dried and freeze−dried apricots. PEF treatment also significantly (p < 0.05) increased amino acid and fatty acid content of air−dried samples but significantly (p < 0.05) decreased sugar content. Almost all amino acids (except tyrosine, alanine, and threonine) significantly increased with increasing PEF intensity. The results of this study suggest that PEF pretreatment can influence the quality of air−dried and freeze−dried apricots in terms antioxidant activity and metabolites such as amino acids, fatty acids, sugar, organic acids, and phenolic compounds. The most effective treatment for preserving the quality of dried apricots is freeze drying combined with high−intensity (1.8 kv/cm) PEF treatment.

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Section: Resultsmentioning

confidence: 99%

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze− and Air−Dried New Zealand Apricots

Liu,

Oey,

Leong

et al. 2024

Foods

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“…Without water present, some phytochemicals, including some isomers of chlorogenic acid, may be more susceptible to degradation and oxidation pathways. Additionally, cell disruption during freezing and dehydration can expose the phytochemicals to endogenous plant enzymes that remain active even after freeze-drying, potentially leading to enzymatic breakdown of these compounds [ 18 – 21 ].…”

Section: Resultsmentioning

confidence: 99%

Fatty acids and chlorogenic acid content in Plectranthus edulis root tubers

Fetene,

Atlabachew,

Sheferaw

et al. 2024

PLoS ONE

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This study quantified the fatty acid profile and total chlorogenic acid content of various Ethiopian cultivars of the Plectranthus edulis tuber, traditionally known as ’Agew Dinich’. Lipid extraction utilized the Folch method and the acid-catalyzed derivatization method to derivatize the fatty acids into fatty acid methyl ester (FAME) were used. Whereas maceration was used to extract chlorogenic acid from the fresh and freeze- dried tuber samples. Analysis revealed a total of thirteen fatty acids in all P. edulis samples, with nine classified as saturated and four as unsaturated. Palmitic acid was the most abundant fatty acid in P. edulis and accounted for 40.57%–50.21% of the total fatty acid content. The second and third most abundant fatty acids in the P. edulis sample were stearic and linoleic acids, which accounted for 8.38%–12.92% and 8.12%–11.28%, respectively. We reported chlorogenic acid for the first time in this potato species and found it to contain a concentration of 211± 4.2–300±24.7 mg/100g of dry weight basis when the determination was made using fresh samples. On the other hand, these samples yielded a chlorogenic acid concentration ranging from 115 ±8.6 mg/100g-175±3.9 mg/100g of freeze-dried powder samples. These findings suggest that P. edulis tubers could represent a significant dietary source of both chlorogenic acid and fatty acids.

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“…The leaves were deep green and had flat surfaces without burnt flavor and bubbles, thus exhibiting the best quality. Wang Li et al [7] discussed the effects of the infiltration dehydration of mulberry before drying on the drying kinetics. Their results showed that the drying rate and water diffusion rate declined due to infiltration dehydration, while the internal resistance against the external diffusion of water increased.…”

Section: Introductionmentioning

confidence: 99%

Optimization and Testing of the Technological Parameters for the Microwave Vacuum Drying of Mulberry Harvests

Cong,

Liu,

Tang

et al. 2024

Applied Sciences

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This study focuses on mitigating the decrease in the quality of mulberry after harvest and increasing the value of mulberry products through microwave vacuum drying. The effects of mulberry moisture content on texture properties were investigated, and the test method was optimized through the membership function model and the central composite technique. The influences of the material surface temperature, vacuum degree, and microwave power on the quality of instant mulberry were analyzed comprehensively. A regression model was established to analyze the relationship between each test factor and quality index. The results show that, with increases in the moisture content, both the hardness and chewiness of mulberry present a decreasing trend; when elasticity increases gradually, adhesivity is presented in an inverted V-shaped variation trend, and the cohesiveness remains basically constant. Moreover, the moisture content of mulberry had significant correlations with elasticity, glueyness, chewiness, and hardness (R2 > 0.9). When the moisture content of the samples reached ≤44.07%, the total plate count reached a minimum and changed gradually; thus, the moisture content (44.07%) of mulberry was determined for the technological optimization test. The combination of optimal technological parameters was as follows: material surface temperature = 51.0 °C, vacuum degree = 0.07 MPa, and microwave power = 370 W. Under these optimal technological parameters, the soluble solid content was 42.37%, chewiness was 9.08, and the Vc content was 0.725 mg·(100 g)−1. The average error between the test results and software optimization parameters was 5.88%. The optimized microwave vacuum drying technological parameters improved the drying quality of mulberry significantly. The results can provide theoretical support for the microwave vacuum drying of berries.

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Effect of vacuum freeze drying and hot air drying on dried mulberry fruit quality

Cited by 12 publications

References 49 publications

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze− and Air−Dried New Zealand Apricots

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze− and Air−Dried New Zealand Apricots

Fatty acids and chlorogenic acid content in Plectranthus edulis root tubers

Optimization and Testing of the Technological Parameters for the Microwave Vacuum Drying of Mulberry Harvests

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