Freeze dried mushrooms

Commercial mushroom tyrosinase was obtained from Sigma Chemical Company (St. Louis, MO). Fresh, frozen, or freeze dried mushrooms (Agaricus bisporus) were supplied by the Campbell Institute for Research and Technology (Napoleon, OH). 

The direct insertion of plant material into the mass spectrometer can give useful information on the constituents present, provided that sufficient data have already been accumulated from synthetic compounds and from conventional phytochemistry. Direct mass spectral analysis (MIKES) of whole freeze-dried mushrooms (Helvella esculenta) indicates the presence of gyromitrin (21 =... 

Kompany, E., Rene, F. Optimal conditions for freeze drying of cultured mushrooms (Agari-cus bisporus) - study of aroma retention. Recent Prog. Genie Procedes, 7 (30) Etudes et Conception d Equipements, p. 267-272, 1993... 

The quantity of toxins in the mushrooms can vary widely. In an analytical study on material confiscated by local authorities in Germany, P. cyanescens had the highest toxin content (Musshoff et al., 2000). As a species that always contains psilocin, P. cyanescens shows bluing. Species that do not always contain psilocin sometimes do not. The reason for this is that the blue color is caused by an oxidation product of psilocin. Both psilocibin and psilocin are temperature-sensitive mushrooms in the freeze-dried state have been reported to retain activity for over two years when kept at -5°C. 

Bursterberger Explosives, Dynamite-type expls claimed not to exude, even at 100°, and not to freeze even at minus 14°, were prepd by impregnating spongy substances, such as cellulose, rotten wood or dried mushrooms with ohondrin or glycocol(glycine) and then adding 26 to 60% NG Ref Daniel(1902), 89... 

Trehalose is a relatively new bulk sweetener with potential for use in soft drinks. It is a di-glucose sugar and it occurs in nature in shellfish and mushrooms, where it confers a degree of protection to plant and animal cells in conditions causing dehydration. This led to its use as a cryoprotectant in freeze-drying systems in the pharmaceutical industry. In food markets, its potential use is as a bulk sweetener. It is manufactured using the Hayashibara patented process using starch as a raw material. The process involves enzymatic conversion and crystallisation to the trehalose dehydrate crystal (LFRA, 2001). 

Maelkki Nikkilae, Aalto and Heinonen [31, 32] stress the importance of the raw material quality of onions. Stieger [33] has investigated the suitablity of various strawberry varieties. Processes for flavour preservation have been thoroughly examined with cultivated mushrooms, leading to an illumination of the most important freeze drying parameters [34[. 

Similarily, blanching water, an inevitable by-product of some production processes, can be used. An example for cultivated mushrooms is described by Wu et al. [62], who compare various drying methods. They report that thermal drum drying has the best sensorical effect. In this case, freeze drying would only be of interest if the main emphasis is on the structure of the granular material. 

Kompany, E. Rene, R Aroma retention of cultivated mushrooms (Agaricus bispoms) during the freeze-drying process. Lebensmittel-Wissenschaft und -Technologic 26 (6), 524-528 (1993)... 

The best of both drying and freezing is freeze drying. This is the ideal method for preserving the flavor, nutrition, form and/or psilocybian content of mushrooms. Because of the expense, only a few commercial mushrooms, such as shiitake Lentinus edodes) are freeze dried. 

Atmospheric freeze-drying of several foods, including mushrooms and carrots, was investigated in a fluidized bed of finely divided adsorbent that combined adsorption and fluidization, achieving improved heat and mass transfer and shorter drying time than vacuum drying [50,51]. Products could be dried economically using very simple equipment. 

Loch-Bonazzi et al. [33] evaluated the quality of mushrooms dried by various processes such as hot air, vacuum, freeze-drying in an adsorbent fluidized bed and vacuum freeze-drying. Results of their study indicated that vacuum freeze-dried products were of superior quality in... 

Fig. 2. Purified mushroom PPO fractions run on a non-denaturing polyacrylamide gel (10% PAGE). Lanes 1 and 9 are blanks where sample buffer only was applied lanes 2, 5 and 3, 6 correspond to aliquots of peaks A and B of the Igg-Sepharose column, respectively. Lanes 4 and 7 are of unpurlfled enzyme and lane 8 is an aliquot of redlssolved freeze dried unpurlfled enzyme (Sigma Chemical Co.). The left part of the gel (lanes 1, 2, 3 and 4) was stained by substrate (DL-dopa 5 nM) reaction In 0.1 sodium phosphate buffer, pH 7.0, with oxygen replenished by bubbling through the Incubation solution. The band In zone a stained brown immediately, while there was a delay of 10 min In the start of color appearance In zone b. The right hand side of the gel (lanes 5, 6, 7, 8, 9) was stained for protein with Coomassle brilliant blue.

Loch-Bonazzi et al. [33] evaluated the quality of mushrooms dried by various processes such as hot air, vacuum, freeze-drying in an adsorbent fluidized bed and vacuum freeze-drying. Results of their study indicated that vacuum freeze-dried produets were of superior quality in terms of density, rehydration eap-acity, and color. They also reported that most flavor compounds disappear during preparation and freezing steps. Microwave vacuum drying of mushroom has been explored by Pappas et al. [34]. Their experimental results indicated that microwave-vacuum drying exhibits superior drying performance as well as improved rehydration characteristics. 

Mushroom tyrosinase was obtained from Sigma Chemical Co., and used without further purification. The enzyme was dissolved in 0.1 M sodium buffer, pH 7, to a concentration of 1 pg/pL, and the amount used in any given experiment depended on the amount of substrate present. Most experiments required 100-200 units of the enzyme. The enzyme solutions were prepared fresh on the day of use. The specific activity of the lot used in these experiments was 4.9 units/pg freeze-dried powder. Since the enzyme requires oxygen for activity, most experimental solutions were sparged with room air using a pasteur pipette at regular intervals during the course of the exposure. 

Kubowitz (1938) has already noted that potato phenolase cannot be dried without considerable loss of activity. Mushroom phenolase, after careful freeze-drying, remains extremely soluble but loses about 70% of its original activity in all the conditions tried the apoenzyme loses about the same amount of its virtual activity. 

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