Studies On Quality Analysis On Major Fujian Peanuts And New Technologies Of Peanut Processing

Peanut(Arachis hypogaea L.)is one of four major oil crops in our country and also the most important oil crop in Fujian Province.It is a plant with high nutrition. As the peanut's nutritional value was revealed gradually,more requirements for its processing were put forward by consumers.Using peanut as raw material to produce salty and crisp peanut in shells has became popular recently.However,the peanut processing technology was backward and its material sources were too many and miscellaneous,which resulted in low product quality and market competitiveness. Nine major peanut cultivars(Minhua 5,Minhua 10,Minhua 6,Shanyou 21,Shanyou 71,Quanhua 10,Quanhua 327,Quanhua 646,Baisha 1016)were collected to study the genetic diversities,nutritional and healthy characters and processing and storing qualities in this thesis.A special peanut cultivar used for processing was selected and the new processing technologies of salty and crisp peanut in shells were also discussed.The all results were as follows:1.5 primers with clear and obvious bands were selected from 90 detainer nucleotide primeres using the method of random amplified polymorphic DNA(RAPD) in 9 peanut cultivars.21 bands with 11 polymorphic were totally produced,which showed that peanut cultivars from same cultivation area had some differences.The similar indexes and cluster analysis indicated that 9 peanut cultivars could be classified into 3 classes.Classâ… :Minhua 6;Classâ…¡:Shanyou 21;Classâ…¢:Minhua 5, Minhua 10,Shanyou 71,Quanhua 10,Quanhua 327,Quanhua 646,Baisha 1016.So RAPD is an effective method for molecular identification.2.The differences of nutritional and healthy characters among 9 peanut cultivars were researched.Components in peanut had great difference because of various plantation and cultivars.The results showed that peanut was not only rich in protein and fat,but also rich in micronutrients.The average contents of protein and fat were 28.08%dry weight and 53.61%dry weight respectively.There was a significant and negative correlation between them,which could provide a reference for selecting high protein and low fat content of peanut cultivar.Peanut amino acids composition was complete.The content of essential amino acids had 30.79%in total content of amino acids.Leucine content was highest, methionine and cystine were lower than other essential amino acids,so sulfur-containing amino acid was the first restrict amino acid in peanut.The contents of oleic acid,linoleic acid,palmitic acid,stearic acid,and arachidic acid were over 2%.Especially the oleic acid was highest in unsaturated fatty acids, which average content was 46.31%,essential fatty acid-the linoleic acid followed with the amount of 36.28%.Peanut trypsin inhibitor was contained in all 9 peanut cultivars,but their activities showed great differences(34.29%).3.The gray relational analysis was used to investigate the nutritional characters of 9 peanut cultivars widely planted in Fujian Province.The results showed that there were great differences about Relationship Grade(γ)between the reference and the individual peanut cultivars.The sequence of relationship grade was:Quanhua 646＞Minhua 5＞Minhua 6＞Quanhua 10＞Minhua 10＞Quanhua 327＞Shanyou 21＞Shanyou 71＞Baisha 1016.Further analysis indicated that Quanhua 646 and Minhua 6 were suitable for directly eating and processing respectively.4.Changes on moisture content,iodine value(â…£),acid value AV),peroxide value(POV)and activities of peroxidase(POD),catalase(CAT)and lipoxygenase (LOX)of 9 peanut cultivars stored for 1 year were measured.Results indicated that POV and AV increased gradually with the storing time,butâ…£and activities of peroxidase(POD),catalase(CAT)and lipoxygenase(LOX)descreased.AV,POV and activity of LOX were choosed for a sensitive index during peanut storing by DPS.When the POV was less than 16 meq/kg,peanut could be suitable for storing.When it reached above 16 meq/kg,peanut was not appropriate for storing.As activity of LOX was more than 140 U/g·min,peanut could be stored for a long time. As it was less than 140 U/g·min,peanut would be aging quickly.9 peanut cultivars were all suitable for storing with appropriate AV,POV and activity of LOX.It indicated that peanut had good storage resistance.5.Bleaching,soaking and roasting parameters were researched and optimized during processing on salty and crisp peanut in shells with Minhua 6.H₂O₂ and peracetic acid were used to bleach peanut shells,which could damage the color groups,make the peanut shells' color uniform,and improve its appearance quality.The optimum technological conditions of peanut bleaching were as follows: pH value was 8,bleaching temperature was 65℃,bleaching time was 15min, concentrations of H₂O₂ and peracetic acid were 3.0%respectively.The results showed when peanut was soaked at 25℃for 1min under vacuum, the liquid absorbability reached 100%.While it was soaked at 25℃for 36h under normal pressure,the liquid absorbability only came to 50.46%.Therefore,vacuum soaking was prior to pressure soaking.The optimum technological conditions for vacuum soaking were:vacuum degree was 0.085MPa,soaking temperature was 55℃, salt concentration was 10%,soaking time was 3min.Traditional roasting technology of salty and crisp peanut in shells was improved by hot air,microwave and far infrared roasting methods.According to fuzzy comprehensive evaluation,the quality of salty and crisp peanut in shells roasted by far infrared technology would be best.The optimized prameters for far infrared roasting were:roasting temperature was 130℃,roasting time was 2.5h,peanut amout was 1.0kg.During the roasting,AV and POV increased while reducing sugar and free amino acid showed certain decrease.Activities of LOX and PTI were all greatly inhibited after roasting,which would be helpful to maintain the nutrition of salty and crisp peanut in shells.6.HACCP principles were applied on salty and crisp peanut in shells processing.Material purchasing,bleaching and roasting were defined as critical control points.The practice on production indicated that products quality and security were greatly improved by the establishment of HACCP.