الفهرس 
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Abstract
Mushrooms are the edible fungi of commercial importance. More than 2000 species of mushroom exist in nature, but only about 22 species are extensively cultivated for commercial purposes. Mushroom converts nutritionally valueless substances into proteinous food, and its bioconversion is efficient. Pleurotus species can produce 1 Kg of fresh mushroom from 1Kg of wheat straw within 30 days, while Agaricus species produce 0.7 Kg of fresh mushroom per Kg of compost.
Consumption of mushrooms has increased substantially due to its delicacy, flavor, nutritional, and medicinal value it considered an excellent source of protein and which contained all of amino acids which important to our bodies and it was had low content of cholesterol and fats while it was rich of vitamins and minerals and can contribute to the formulation of a balanced diet.
Two samples of mushrooms button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus) were used.
This Study aims to examine the effects of radiation, blanching, Soaking and manufacturing processes (canning, drying) on the components of the food and chemical constituents of mushrooms. This can be illustrated by the results that could by summarized as follows:
Chemical composition.
The results showed that white button mushrooms (Agaricus bisporus) contained lower content of moisture than oyster one Pleurotus ostreatus. The same trend was observed for the contents of total soluble sugars , L- Ascorbic acid and total carotenoids. But in the case of crude protein, total Phenolic compounds and total flavonoids, their concentrations were higher than in oyster Pleurotus ostreatus.
Treatment with irradiation.
It was technological process used in food preservation to extending shelf life from 25:30 days and effaced food from microorganisms which caused turn bad. And it was safe treatment
Effect of different irradiation doses on the chemical constituents of mushrooms.
The effect of different dose of irradiation ( 2.5, 7.5 and 10 kGy), showed that the content of crude protein in both two edible mushrooms was decreased when we used different dose of irradiation, total soluble sugars in the treated samples showed an increase in its amounts especially the treatment with 2.5 kGy and 7.5 than 10 kGy, L-ascorbic and the treatment with 2.5 kGy than the others 7.5 and 10 kGy showed an increase in its amounts in both two edible mushrooms.
The irradiation process led to an increases in total Phenolic compounds TPCs, but in the case of flavonoid contents there is no remarkable changes due to the effect of irradiation, the irradiation caused significant increases in the total carotenoids.
Effect of irradiation doses on enzyme activities of mushrooms.
The activity of polyphenoloxidase and tyrosinase in Agaricus bisporus were higher than that in Pleurotus ostreatus, and the irradiated samples exhibited lower polyphenoloxidase and tyrosinase activity compared to non-irradiated controls, the peroxidase activity were lower in the two types, and the activity of the enzyme in (Agaricus bisporus) was higher than that in Pleurotus ostreatus, and the activity of the enzyme in irradiated samples was lower than in non- irradiated samples (control).
The activity of phenylalanine ammonia – lyase and proteases activity in Agaricus bisporus were lower than that in Pleurotus ostreatus, and there was a remarkable changes in the activities of phenylalanine ammonia – lyase in Agaricus bisporus at high dose on Pleurotus ostreatus, the effect of different dose of irradiation on the levels of proteases in Agaricus bisporus and Pleurotus ostreatus were limited except low irradiation dose (2.5kGy).
Effect of blanching and soaking on the chemical constituents of mushrooms.
Blanching treatment of preheated (sun dried and oven dried) samples after storage period led to slight decreases (9-10%) In CP exist in Agaricus bisporus and higher percents (12-15%) in Pleurotus ostreatus, and the use of sodium metabisulfate only or with CA led to slight reduction In CP for both fungi, and more than 35% and16.8% in Agaricus bisporus and Pleurotus ostreatus (Sun dry) were lost from the contents of TSS during storage period , respectively, and soaking using SMS led to decreases in TSS for both fungi, it could be ordered the treatments as follows: Blanching > soaking in SMS> soaking in CA+SMS.
Blanching and soaking treatments led to a great loss for L-ascorbic acid in the two variety Agaricus bisporus and Pleurotus ostreatus.
We noticed that all treatments were found to cause a reduction in the total Phenolic compounds when compared with the contents of fresh mushrooms. It could be noticed that the soaking in sodium metabisulfate exhibited the high level ratio than other treatments and that in both samples respectively, and the blanching treatments is considered one of the important operation during mushroom processing. Blanching and soaking treatments led to a great loss for total flavonoids in the two variety Agaricus bisporus and Pleurotus ostreatus.
In all treatment studied there a loss in total carotenoids were varied in both samples and both treatments sun dry and oven dry during the different storage period, in both different treatment sun dry and oven dry the soaking in sodium metabisulfate was favored because its less loss in other antioxidant material during storage period.
Effect of blanching and soaking on enzymes activities of mushrooms.
All treatments caused reduction on the activity of (PPO, tyrosinase and peroxidase) when we compared it with control, and it could be put our treatments in order to which of them have more effect on decreased activity of (PPO, tyrosinase and peroxidase) as follow:- Blanching > soaking in CA+SMS> soaking in SMS, (TPCs) were increased as a result of blanching and soaking during storage periods, and the higher in PPO activity led to an increase of phenol concentration, chemical processing treatments inhibit stimulation of PAL activity and the synthesis of Phenolic compounds which are important in extending storage periods,
Blanching and soaking treatments led to decrease the activity of proteases in both samples, and we can notice that there is no significant difference between all treatments.
Effect of Processing on chemical constituents of mushrooms.
To improve keeping quality acceptability and shelf life of mushroom, fresh harvested Agaricus bisporus and Pleurotus ostreatus mushrooms were subjected to different processing treatment (Canning and drying).
In canning treatment their considerable loss of crude protein. Sun drying and oven drying caused a definite reduction of protein, and there was a great loss in soluble sugars than drying methods, but there is a little effect of drying methods on total soluble sugars comparable to canning method.
While the loss percentage of ascorbic acid, was higher in canning processing, while the loss percentage were lower in sun dry process in, while it was less in oven dry method in the two processed mushroom, in canning process TPCs decreased to ~76 %. While drying methods caused a considerable increased in polyphenolic compounds, ~6% in sun dry methods, whereas it reached 10 % and 5.8 % in an oven dry method in both two species respectively.
Flavonoids are decreased during canning process, Drying methods of Agaricus bisporus and Pleurotus ostreatus sample increased the over all content of total Phenolic and flavonoid compounds.
The amount of total carotenoids was decreased in canning and drying methods and reached to 82.9 % and 73.5 % in the samples respectively in canning methods, but in sun dry methods it reached 64.1 and 65.1 % in the two samples respectively, in (oven dry) it reached 54.8 % and 75.4 % in the two samples respectively.
Effect of processing on enzymatic activities of mushrooms.
Dehydration and canning process caused a great inhibition for polyphenoloxidase. The ratio was (91.7 and 88.9 %) in Agaricus bisporus and Pleurotus ostreatus respectively in canning process. While it reached to (43.8 and 22.2 %) in sun dry process in the two samples respectively and in an oven dry method was (41.7 and 11.1 %) in the two samples respectively. Canning process caused a great inhibition for tyrosinase reached 76.4 and 75% in Agaricus bisporus and Pleurotus ostreatus respectively, while the change in the activity of tyrosinase in Agaricus bisporus and in Pleurotus ostreatus, was the same in sun dry and oven dry.
Also Canning process caused a great inhibition for peroxidase. was (80.9 and 79.2%) in Agaricus bisporus and Pleurotus ostreatus respectively, in canning process, and drying methods also caused inhibition was (74.9 and 71.2% sun dry method) and (75.4 and 72.8% oven dry) in the two samples respectively.
The activity of phenylalanine ammonia- lyase in canning and dehydration methods there is no significant differences in all treatments during the different storage period in both samples.
Proteases seemed to be higher in Pleurotus ostreatus (160 µg RAA/ 60 min) than in Agaricus bisporus which its activity was (95.5 µg RAA/ 60 min). there are no significant differences in all treatment during the different storage period of the mushroom in both samples.
Effect of different processing treatments on Free amino acid composition.
Agaricus bisporus contained the highest amount of total amino acids (79.6 µg/g) whereas Pleurotus ostreatus contained the lowest amount of amino acids (63.7 µg/g).
The major amino acids found in Agaricus bisporus were glutamic acid, aspartic acid, histidine, arginine, leucine and alanine, those in Pleurotus ostreatus glutamic acid, aspartic acid, arginine and alanine.
Leucine was found to be most abundant in all processed samples, the second most abundant essential amino acid in the two species was Lysine. While Valine was the third most abundant essential amino acid.
γ-amino butyric acid (GABA) a hypertensive agent was found in both samples.
Effect of different processing treatments on free sugar content.
The contents of free sugars in fresh sample (control) in Agaricus bisporus were higher (171.92 mg/g DW basis) than that found in Pleurotus ostreatus (42.38 mg/g DW basis).
The two species contained nine free sugars, mannitol, glucose, sucrose, arabinose fructose, raffinose, mannose, stachyose and galactose in descending order respectively in Agaricus bisporus whereas in Pleurotus ostreatus were glucose, mannitol, galacturonic acid, sucrose, stachyose, arabinose, fructose, galactose and mannose respectively.
There are a great loss of contents of free sugars in both species and all different treatments.