Effects of Prior Freezing Conditions on the Quality of Blueberries in a Freeze-Drying Process

2017 ◽  
Vol 60 (4) ◽  
pp. 1369-1377 ◽  
Author(s):  
Hien Thi Ngo ◽  
Seishu Tojo ◽  
Takuya Ban ◽  
Tadashi Chosa
Keyword(s):  
Freeze Drying ◽  
Far Infrared ◽  
Aroma Compounds ◽  
Operating Conditions ◽  
Test Material ◽  
Freezing Process ◽  
Sublimation Process ◽  
Freeze Dried ◽  
Infrared Heater ◽  
Ice Crystal Size

Abstract. Freeze-drying has played an increasingly important role in the production of dehydrated foods. This article discusses the operating conditions of the prior freezing process of blueberry fruit to maintain the fruit aroma during the sublimation process. The properties of frozen fruit, such as ice crystal size, seem to depend on the freezing speed, leading to some aroma loss during the sublimation process. The temperature of the deep freezer was set at -20°C, -40°C, -60°C, or -80°C to determine the effects of changing the freezing speed of blueberries during prior freezing. Northern highbush blueberry cultivars Dixi and Elliott harvested in a university orchard (Tokyo, Japan) were used as the test material. The sublimation process of freeze-drying was done using a transparent vacuum desiccator connected to a vacuum pump through a vapor cooling trap under heating conditions provided by a far-infrared heater. Trapped vapors were analyzed with GC-MS to identify and quantify the aroma compounds of the blueberries, such as benzaldehyde. The change in the appearance of the freeze-dried blueberries following prior freezing at various speeds is also described. The amounts of typical volatile compounds, such as acetic acid, 2-hexanol, and 3-hexanol, decreased as the freezing speed increased. Most volatile aroma compounds could be preserved when blueberries were frozen rapidly in a deep freezer. Keywords: Aroma loss, Blueberry, Freeze drying, Freezing speed, Prior freezing.

Investigation of Volatile Reducing Substances as an Indicator of Decomposition for Raw and Processed Foods

1969 ◽  
Vol 52 (6) ◽  
pp. 1135-1141
Author(s):  
Barbara R Moorhouse ◽  
Harold Salwin
Keyword(s):  
Freeze Drying ◽  
Aeration Rate ◽  
Operating Conditions ◽  
Processed Foods ◽  
Reference Solution ◽  
Empirical Procedure ◽  
Freeze Dried ◽  
Experimental Parameters ◽  
Raw Foods ◽  
Reducing Substances

Abstract Volatile reducing substances (VRS) in foods were determined by an empirical procedure in which volatiles are stripped by aeration from an aqueous extract of a sample, passed through alkaline potassium permanganate, and measured by the extent of permanganate reduction. Experimental parameters were investigated as a step toward developing a standardized procedure. Dilute methanol was investigated as a reference solution, the equipment described in published procedures was simplified, and some operating conditions were controlled. The amount of permanganate reduction increased with length of aeration, but variations in aeration rate from 1360 to 1790 ml/min were not critical. The method was applied to ground beef, shrimp, and peaches. The raw food materials were stored at ice or refrigeration temperatures until they reached a decomposed state. Samples withdrawn at intervals during storage were processed and preserved by freezing or by freeze-drying. The content of VRS in raw samples increased as the foods decomposed. The VRS were partly lost during cooking and completely lost during freeze-drying. Therefore, the VRS content appears to have promise as an index of decomposition for a variety of raw foods and possibly for some cooked foods, but not for foods that have been freeze-dried.

scholarly journals Influence of Freezing Parameters on the Formation of Internal Porous Structure and Its Impact on Freeze-Drying Kinetics

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1273
Author(s):  
Patrick Levin ◽  
Vincent Meunier ◽  
Ulrich Kessler ◽  
Stefan Heinrich
Keyword(s):  
Internal Structure ◽  
Freeze Drying ◽  
Crystal Size ◽  
Single Layer ◽  
Drying Kinetics ◽  
Freezing Process ◽  
Drying Time ◽  
Air Blast ◽  
Temperature Cycles ◽  
Freeze Dried

The main objective of this study was firstly to investigate the influence of freezing process parameters on the formation of the internal structure of frozen coffee granules. It was investigated how these frozen internal structures affect the drying kinetics during freeze-drying. A design of experiment study was carried out using the response surface method to quantify the influence of the freezing step that occurs in a scraped surface heat exchanger (SSHE). Therefore, the coffee extract at a concentration of 30% w/w is entering the SSHE as a liquid and gets partially crystallized up to a weight-based ice content of 0.364. During this step, the influence of factors like cooling temperature, scraper rotation speed and temperature cycles on ice crystal structure was investigated. In a second freezing step, the influence of freezing rates during hardening of the product by air-blast freezing is investigated, where the freezing rate is significantly affected by the cake thickness. The produced frozen granules were freeze-dried in single layer experiments. During drying the influence of internal structure on the drying kinetics was investigated. Results show that all factors have a significant impact on structure parameters for 30% w/w coffee solutions. A lower degree of supercooling during freezing in an SSHE, a higher number of temperature cycles (2 to 8 times) and lower freezing rates during hardening (2 °C/min to 10 °C/min) were leading to increased crystal size. This increase accelerates the primary drying rate and decreases the total drying time. A higher number of temperature cycles leads to a significant increase of crystal size and therefore larger pore size at the end of the primary drying. Furthermore, in combination with temperature cycles in the SSHE, it was found that high freezing rates during air blast freezing generally lead to a second nucleation step of ice crystals.

Preparation and Characterization of Freeze-dried Liposomes Loaded with Amphotericin B

2019 ◽  
Vol 14 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Tran Thi Hai Yen ◽  
Le Nho Dan ◽  
Le Hoang Duc ◽  
Bui Thanh Tung ◽  
Pham Thi Minh Hue
Keyword(s):  
Amphotericin B ◽  
Freeze Drying ◽  
Entrapment Efficiency ◽  
Freezing Process ◽  
Scanning Calorimetry ◽  
Citrate Buffer ◽  
Lipid Film ◽  
Freeze Dried ◽  
Liposomal Suspension

Background: Amphotericin B (AmB) is a drug of choice in the therapy of systemic fungal infection because of its board-spectrum antifungal activity. However, its conventional formulation has many side effects such as acute and chronic nephrotoxicity. Liposomes have been developed to reduce the drug’s toxicity. However, they had to meet strict stability criteria. In general, liposomes can be freeze-dried to inhibit liposomes infusion, phospholipids degradation during storage. Liposomal size usually increases after freeze-drying because of being influenced by many factors in freezing, lyophilizing and rehydration processes. Therefore, cryoprotectants are used to stabilize liposomal vesicles during freeze-drying process. </P><P> Objective: In the present study, we developed AmB liposomal suspension and lyophilized liposomes loaded with AmB, evaluated the effect of different cryoprotectants on the characterization of freeze-dried AmB liposomes. </P><P> Methods: In this study, AmB liposomes were prepared from hydrogenated soy phosphatidylcholine, distearoylphosphatidylglycerol and cholesterol by thin lipid film hydration method using different hydrate mediums likely: Glucose solution, citrate buffer, phosphate buffer. High-pressure homogenization and extrusion methods were used to reducing vesicles size. Dynamic light scattering was used to characterize liposomal size, and size distribution. HPLC method was used to assay drug and determine entrapment efficiency. Liposomal suspension was lyophilized with different cryoprotectants: Sucrose, mannitol, lactose, trehalose and glycerol. Differential scanning calorimetry was used to study lyophilized cake. </P><P> Results: We found that liposomal suspension with hydration medium10 mM citrate buffer pH 5.5 had a small average size (<100nm) and narrow distribution (PDI <0.2). Sucrose and trehalose stabilized vesicles size during freezing process, and lyophilized liposomes with sucrose and trehalose had an elegant appearance, yellow, compact cake. DSC study showed that sucrose and trehalose in lyophilized cake were amorphous. The cake was rehydrated within 10 seconds to form liposomal suspension, in which vesicles size was less than 140 nm. </P><P> Conclusion: We have developed successfully AmB liposomal suspension and lyophilized liposomes loaded with AmB. Sucrose and trehalose can be used as cryoprotectants in the freeze-drying and reconstitution process.

scholarly journals Effect of hot air and freeze drying on the volatile compounds of dill (Anethum graveolens L.) herb

1985 ◽  
Vol 57 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Rainer Huopalahti ◽  
Eila Kesälahti ◽  
Reino Linko
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Volatile Compounds ◽  
Freeze Drying ◽  
Aroma Compounds ◽  
Gas Chromatography Mass Spectrometry ◽  
Volatile Components ◽  
Anethum Graveolens ◽  
Hot Air ◽  
Freeze Dried

Volatile compounds of fresh, hot air dried and freeze dried dill (Anethum graveolens L.) herb were studied by gas chromatography-mass spectrometry. Of the 25 volatile components identified, 16 the most abundant compounds were analysed quantitatively. The major primary aroma compounds were α-phellandrene, 3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran,β-phellandrene, limonene, α-pinene, p-cymene and myristicin. Severe loss of these components occured during the drying of dill. E.g. the retention of the benzofuranoid, the most important aroma component of the dill herb, was from trace to 1.3 % in hot air dried samples and 3.5—20 % in freeze dried samples. During the drying secondary aroma compounds are formed consisting over 50 % of the total volatiles. Among these phytadienes, especially neophytadiene, were the major components. The best result was obtained by freeze drying, but the product contained only one quarter of the total aroma compounds of the fresh dill herb.

scholarly journals Ultrastructure and energy-dispersive x-ray microanalysis of cartilage after rapid freezing, low temperature freeze drying, and embedding in Spurr's resin.

1985 ◽  
Vol 33 (10) ◽  
pp. 1073-1079 ◽  
Author(s):  
J Appleton ◽  
R Lyon ◽  
K J Swindin ◽  
J Chesters
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Energy Dispersive ◽  
Freezing Process ◽  
Rapid Freezing ◽  
Thin Sections ◽  
X Ray ◽  
Freeze Dried ◽  
Rapid Production ◽  
Ideal Method

In order to undertake meaningful high-resolution x-ray microanalysis of tissues, methods should be used that minimize the introduction of artefacts produced by loss or translocation of ions. The most ideal method is rapid freezing but the subsequent sectioning of frozen tissues is technically difficult. An alternative method is to freeze dry the tissues at a low temperature, and then embed them in resin. This facilitates the rapid production of reproducible thin sections. With freeze-dried, embedded hypertrophic cartilage, the morphology was similar to that seen using aqueous fixatives even when no additional electron density is introduced by the use of osmium vapor. Energy-dispersive analysis of specific areas show that little or no loss or migration of ions occurs from structures such as mitochondria. Mitochondrial granules consisting of calcium and phosphorus precipitates were not observed except where the cells were damaged as a result of the freezing process. This may suggest that these granules only appear when tissue is damaged because of inadequate preservation.

Freezing and freeze-drying

1975 ◽  
Vol 191 (1102) ◽  
pp. 9-19 ◽  
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Storage Temperature ◽  
Research Work ◽  
High Water Content ◽  
Freezing Process ◽  
Neutral Atmosphere ◽  
Reduced Pressure ◽  
Freeze Dried ◽  
Frozen State

Most biological substances are unstable during storage owing to their high water content. This is why numerous attempts have been made over the last 100 years to prevent, by low temperature freezing, metabolic and biochemical degradations. The transformation of water into ice brings to an end all chemical reactions; however, it might also induce deleterious alterations into the delicate structure of many products. A brief review of the basic phenomena involved in the freezing process of biological substances helps to understand how the cooling cycles, storage temperature and subsequent rewarming have to be monitored in each individual case. Despite the fact that preservation in the frozen state offers wide possibilities, it is still difficult to apply in some instances, since it implies a continuous low temperature storage and transportation. This is why freeze-drying, or lyophilization, has been introduced. It is a two-step process in which the products to be preserved are deep frozen first, then dried by direct sublimation of the ice under reduced pressure. When completely dehydrated the substances can be stored almost indefinitely if kept in a dry, neutral atmosphere and in the dark. Fundamental aspects of the freeze-drying process will be discussed. Recent research work has shown that drying by sublimation from the frozen state can be performed with other systems than aqueous media. Solutions of lipophilic compounds, fats, phospholipids, steroids, in organic solvents can be ‘freeze-dried’ at low temperatures and high velocities. This particular technology opens new fields for the preservation of delicate materials of living origins.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

scholarly journals Effect of Freeze Drying and Simulated Gastrointestinal Digestion on Phenolic Metabolites and Antioxidant Property of the Natal Plum (Carissa macrocarpa)

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1420
Author(s):  
Faith Seke ◽  
Vimbainashe E. Manhivi ◽  
Tinotenda Shoko ◽  
Retha M. Slabbert ◽  
Yasmina Sultanbawa ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Array Detector ◽  
Gastrointestinal Digestion ◽  
Liquid Chromatograph ◽  
Antioxidant Power ◽  
Intestinal Phase ◽  
Glucosidase Activity ◽  
Freeze Dried ◽  
Small Intestinal ◽  
The Impact

Natal plums (Carissa macrocarpa) are a natural source of bioactive compounds, particularly anthocyanins, and can be consumed as a snack. This study characterized the impact of freeze drying and in vitro gastrointestinal digestion on the phenolic profile, antioxidant capacity, and α-glucosidase activity of the Natal plum (Carissa macrocarpa). The phenolic compounds were quantified using high performance liquid chromatography coupled to a diode-array detector HPLC-DAD and an ultra-performance liquid chromatograph (UPLC) with a Waters Acquity photodiode array detector (PDA) coupled to a Synapt G2 quadrupole time-of-flight (QTOF) mass spectrometer. Cyanidin-3-O-β-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside (Cy-3-G) were the dominant anthocyanins in the fresh and freeze-dried Natal plum powder. Freeze drying did not affect the concentrations of both cyanidin compounds compared to the fresh fruit. Both cyanidin compounds, ellagic acid, catechin, epicatechin syringic acid, caffeic acid, luteolin, and quercetin O-glycoside from the ingested freeze-dried Natal plum powder was quite stable in the gastric phase compared to the small intestinal phase. Cyanidin-3-O-β-sambubioside from the ingested Natal plum powder showed bioaccessibility of 32.2% compared to cyanidin-3-O-glucoside (16.3%). The degradation of anthocyanins increased the bioaccessibility of gallic acid, protocatechuic acid, coumaric acid, and ferulic acid significantly, in the small intestinal digesta. The ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activities, and inhibitory effect of α-glucosidase activity decreased in the small intestinal phase. Indigenous fruits or freeze-dried powders with Cy-3-Sa can be a better source of anthocyanin than Cy-3-G due to higher bioaccessibility in the small intestinal phase.

Process for production of microencapsulated anthocyanin pigments from Rosa pimpinellifolia L. fruits: optimization of aqueous two-phase extraction, microencapsulation by spray and freeze-drying, and storage stability evaluation

2020 ◽  
Vol 16 (9) ◽  
Author(s):  
Halil İbrahim Odabaş ◽  
Ilkay Koca
Keyword(s):  
Freeze Drying ◽  
Fold Increase ◽  
Drying Methods ◽  
Phase Extraction ◽  
Extraction Temperature ◽  
Two Phase ◽  
Freeze Dried ◽  
Anthocyanin Pigments ◽  
Promising Source ◽  
Aqueous Two Phase Extraction

AbstractRosa pimpinellifolia L. fruits (RPF) are promising source of anthocyanin pigments. The objectives of this study were to optimization of the aqueous two-phase extraction (ATPE) process of anthocyanin from RPF and microencapsulation of anthocyanin-rich RPF extract. The optimal ATPE conditions were as follows: 0% HCl, 30% ethanol, 19% ammonium sulfate, and liquid to solid ratio 51.71, 97.71 min, and 30°C extraction temperature. Predicted anthocyanin yield at the optimum conditions was 1578.90 mg cyanidin 3-glucoside equivalent/100 g dry fruit. ATPE resulting in 1.80-fold increase in the purity of anthocyanins when compared to conventional solvent extraction (CSE). The composition of the anthocyanins were determined with HPLC-QTOF-MS. Freeze-drying and spray-drying methods were employed for the production of microencapsulated anthocyanin pigments. The half times of microencapsulated anthocyanins at 4, 25 and 37°C were determined as 12.16, 6.60 and 3.12 months for freeze-dried microcapsules, and 16.50, 9.24 and 4.29 months for spray-dried microcapsules, respectively.

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