Loss of structure in freeze-dried carbohydrates solutions: Effect of temperature, moisture content and composition

1976 ◽  
Vol 27 (6) ◽  
pp. 509-519 ◽  
Author(s):  
Spyros Tsourouflis ◽  
James M. Flink ◽  
Marcus Karel
Keyword(s):  
Moisture Content ◽  
Effect Of Temperature ◽  
Freeze Dried

scholarly journals Water adsorption isotherms and isosteric sorption heat of spray-dried and freeze-dried dehydrated passion fruit pulp with additives and skimmed milk

2011 ◽  
Vol 35 (6) ◽  
pp. 1196-1203 ◽  
Author(s):  
Kelly Tafari Catelam ◽  
Carmen Sílvia Fávaro Trindade ◽  
Javier Telis Romero
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Gum Arabic ◽  
Passion Fruit ◽  
Drying Methods ◽  
Fruit Pulp ◽  
Heat Of Sorption ◽  
Freeze Dried ◽  
Equilibrium Data ◽  
Skimmed Milk

Moisture equilibrium data of passion fruit pulp powders with maltodextrin and gum arabic were obtained by two different drying methods (spray drying and freeze drying) and determined at 20, 30, 40 and 50º C. Skimmed milk was used to substitute part of these additives in the samples. One formulation using passion fruit pulp/maltodextrin/skimmed milk (PMS) was prepared, and another using passion fruit pulp/gum arabic/skimmed milk (PGS). The behavior of curves was type III, according to Brunauer's classification. GAB models were fitted to experimental equilibrium data. The parameters obtained from GAB models was affected by the presence of additives. The behavior of the sorption isotherms for different temperatures are similar, noting only a small effect of temperature. There were little differences between both drying methods and additives used in relation to equilibrium moisture content. The parameters obtained with the addition of the skimmed milk were considered satisfactory (Xm values ranged from 0,04084 to 0,06488 in dry basis), demonstrating that it is an effective and cheap alternative for regular additives. A progressive increase in the heat of sorption in relation to decreasing moisture content was observed and the heat of sorption values of different samples are all similar, comparing the relative equilibrium moisture content.

scholarly journals Fortified and freeze-dried kiwi fruit (Actinidia deliciosa): quality and sensory assessment

2020 ◽  
Vol 23 ◽  
Author(s):  
Niladri Chakraborty ◽  
Rajat Chakraborty ◽  
Asit Kumar Saha
Keyword(s):  
Moisture Content ◽  
Freeze Drying ◽  
Raw Materials ◽  
Food Product ◽  
Rice Flour ◽  
Actinidia Deliciosa ◽  
Crude Fibre ◽  
Kiwi Fruit ◽  
Drying Time ◽  
Freeze Dried

Abstract Kiwi fruit (Actinidia deliciosa) (KF) is one of the best fruits available due to its large amount of nutrients. Despite its many health benefits, there are no previous reports on its preparation in other readily ingestible forms. The objective of the present study was to make a new food product from KF. The KF pulp was fortified and blended with several raw materials (such as rice flour and oat flour) using a stepwise short time addition and mixing methodology since this avoids unwanted biochemical and chemical reactions. The blended and reduced moisture KF paste was freeze-dried on a round silver coated steel plate (RSCSP), supplying the heat of sublimation using a newly designed cubic heater. The freeze-drying (FD) time was 4.5 h and the drying kinetics were studied using four established models. The effective moisture diffusivity (Deff) during FD (at 50 °C) was 1.532 x 10-6 m2/s and the activation energy (E) estimated for the FD was 28.35 kJ/mol. The freeze-dried sample was ground and placed under vacuum to reduce the weathering effects. The quality of the stored product was evaluated using the proximate analysis, physicochemical analysis and a sensory evaluation using a hedonic scale. The raw, fresh KF had a moisture content of 85.07% and the final freeze-dried product one of 3%. The carbohydrate, total sugar, protein, fat, total ash, crude fibre and vitamin C contents of the final product increased by 563%, 400%, 355%, 386%, 672%, 106%, and 117% respectively. Of the 66 panelists, the % consumer acceptances for the different attributes were: sweetness (68.18%), sourness (90.91%), saltiness (100%), bitterness (100%), flavour (95.45%), texture (77.27%) and overall acceptability (81.82%). Using conventional freeze-drying (CFD) for blended KF pulp without fortification, with the same RSCSP and the same cubic heater for sublimation, the drying time was found to be 7 h to reach the same final moisture content of 3%.

scholarly journals Effect of Size and Drying Time on the Rehydration and Sensory Properties of Freeze-Dried Snails (Achatina achatina)

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Matthew A. Achaglinkame ◽  
Eric Owusu-Mensah ◽  
Abena A. Boakye ◽  
Ibok Oduro
Keyword(s):  
Moisture Content ◽  
Nutritional Value ◽  
Freeze Drying ◽  
Consumer Preference ◽  
Sensory Properties ◽  
Temperature Dependent ◽  
Drying Time ◽  
Standard Methods ◽  
Freeze Dried ◽  
Hedonic Scale

Snails, a delicacy in most tropical communities, are highly perishable and seasonal. Employed preservative methods are highly temperature dependent, adversely affecting their nutritional value and sensory properties. This study was aimed at determining the effect of size and drying time on the rehydration and sensory properties of freeze-dried snails. Snails were sized into three categories with average weights: 7.59 g (quarter-sized), 14.41 g (half-sized), and 30.71 g (whole), and freeze-dried for 15, 20, and 25 h. The moisture content and percent rehydration of the dried samples were determined by standard methods and sensory properties assessed by an in-house panel of 30 using a 5-point hedonic scale. The moisture content of the fresh and freeze-dried samples ranged from 65.80 to 75.20% and 3.25 to 10.24%, respectively. Freeze-dried samples had higher percent rehydration (27 to 102%) than the control; smoked snails (21 to 32%). Size had a significant (P<0.05) effect on the rehydration ability of the samples with the half-sized and freeze-dried for 15 h samples having the highest. The freeze-dried samples generally had higher consumer preference than the control in all attributes assessed. The findings show that freeze-drying snails (approximate weight of 14.4 g) for 15 h could be a consumer-preferred alternative preservative method for extending the shelf life of snails.

The Effect of Hydrothermal Dewatering Temperature on Hydro-Char Obtained from Oily Scum

2019 ◽  
Vol 971 ◽  
pp. 127-133
Author(s):  
Shuang Hui Deng ◽  
Xue Bin Wang ◽  
Dao Yang Ma ◽  
Xu Chao Lu ◽  
Hou Zhang Tan
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Surface Characteristics ◽  
Gas Content ◽  
Effect Of Temperature ◽  
Content Increase ◽  
Liquid Content ◽  
Physico Chemical ◽  
Methylene Groups ◽  
Reactor Temperature

Oily scum was treated by hydrothermal dewatering (HTD) under 120-240°C. The changes of surface characteristics and physico-chemical structure of oily scum were investigated and the effect of temperature on the properties of the hydro-char obtained from oily scum was analyzed through different characterization techniques. Results show that the moisture content of HTD treated hydro-char decreases as the temperature increases, which implies that the oily scum can be dewatered and upgraded through HTD method. The morphologies of the HTD pretreated oily scum present less oil content, smaller particle size, and become darker. As the reactor temperature increases from 120 to 240°C during the HTD process, the moisture content of hydro-char obtained decreases from 35.51 to 11.31%, while the liquid content and hydro-char content increase from 58.53 to 79.76% and from 2.50 to 5.29%, respectively, and the released gas content slightly varies in the range of 3.14 - 4.31%. The breaking and gathering effects of the HTD upgrading on oily scum result in a wide particle size distribution of products, which indicates that the overall structure of raw oily scum has been destroyed. With the increase of HTD temperature, the shorten vibration of methylene groups in hydro-char products is weakened.

scholarly journals Storage of seeds of Calamus palustris var. cochinchinensis

2020 ◽  
Vol 48 (2) ◽  
pp. 201-207
Author(s):  
Y.K. Fan ◽  
M. Liu ◽  
J.X. Hu ◽  
M.Y. Ji ◽  
Q.Y. Lan
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Storage Temperature ◽  
Aluminum Foil ◽  
Effect Of Temperature ◽  
Seed Moisture Content ◽  
Seed Desiccation ◽  
Seed Moisture ◽  
Mature Seeds

The present study examined the effect of temperature (15, 20, 25, 30 and 20/30°C) on germination and the storage behaviour of freshly harvested mature seeds of Calamus palustris var. cochinchinensis. Seed desiccation tolerance and the effects of storage temperature (4 and 15°C), perlite water content (120, 180 and 240%) and seed moisture content (27.8, 38.2 and 49.2%) on viability were observed. Seeds had a higher germination at 25°C (88.3%) than at the other tested temperatures. Germination decreased as the seed moisture content decreased during desiccation. The germination of seeds stored at 15°C was higher than that of seeds stored at 4°C. Germination of seeds stored at 15 and 4°C was <65% and with extension of storage time, the germination decreased, indicating that neither temperature can be used for long-term conservation. For short-term storage, the seeds can be stored at 15°C with perlite with 180% water content in plastic bottles or at 15°C with 49.2% moisture content sealed inside aluminum foil bags.

scholarly journals Optimised Extraction of Trypsin Inhibitors from Defatted Gac (Momordica cochinchinensis Spreng) Seeds for Production of a Trypsin Inhibitor‐Enriched Freeze Dried Powder

Separations ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 8 ◽  
Author(s):  
Anh V. Le ◽  
Sophie E. Parks ◽  
Minh H. Nguyen ◽  
Paul D. Roach
Keyword(s):  
Moisture Content ◽  
Freeze Drying ◽  
Trypsin Inhibitors ◽  
Seed Kernel ◽  
Solvent Ratio ◽  
Optimal Conditions ◽  
High Solubility ◽  
High Quality ◽  
Freeze Dried ◽  
Momordica Cochinchinensis

The seeds of the Gac fruit, Momordica cochinchinensis Spreng, are rich in trypsin inhibitors (TIs) but their optimal extraction and the effects of freeze drying are not established. This study aims to (1) compare aqueous solvents (DI water, 0.1 M NaCl, 0.02 M NaOH and ACN)/water/FA, 25:24:1) for extracting TIs from defatted Gac seed kernel powder, (2) to optimise the extraction in terms of solvent, time and material to solvent ratio and (3) to produce a TI-enriched freeze-dried powder (FD-TIP) with good characteristics. Based on the specific TI activity (TIA), the optimal extraction was 1 h using a ratio of 2.0 g of defatted powder in 30 mL of 0.05 M NaCl. The optimisation improved the TIA and specific TIA by 8% and 13%, respectively. The FD-TIP had a high specific TIA (1.57 ± 0.17 mg trypsin/mg protein), although it also contained saponins (43.6 ± 2.3 mg AE/g) and phenolics (10.5 ± 0.3 mg GAE/g). The FD-TIP was likely stable during storage due to its very low moisture content (0.43 ± 0.08%) and water activity (0.18 ± 0.07) and its ability to be easily reconstituted in water due to its high solubility index (92.4 ± 1.5%). Therefore, the optimal conditions for the extraction of TIs from defatted Gac seed kernel powder followed by freeze drying gave a high quality powder in terms of its highly specific TIA and physical properties.

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