Studies On By-products From Some Vegetables:

Mahmoud Hassan Mohammed Mahmoud

This investigation included a study on the utilizationof some vegetable crops wastes,. The raw materials usedwere: watermelon, carrot haulm, cauliflower leaves andartichoke bracts.The objectives of these studies included the followingitems:-A) The chemical composition of raw materials.B) Preparing leaf protein concentrate (LPC).C) Production of single cell protein (SCP) by fungal growth(Aspergillus niger) and yeasta! growth (Saccharomycescerevisiae) from different substrates.D) Production of pectin.The obtained results could be summarized as follows:-A) The che.tcal co.positioD of rav .at.rials iDdicatedthat:1- Watermelon juice contained higher percentage of totalsugars (76.18%, on dry weight basis).2- Carrot haulm and cauliflower leaves contained higherpercentage of crude protein (21.28 and 19.36%; on dryweight basis, respectively).3- Watermelon peels and artichoke bracts contained agood percentage of pectin (10.13 and 6.54%, respectively,on dry weight basis).4- The protein content was 24.13 and 26.67%, on dryweight basis in juices of carrot haulm and of cauliflowerleaves, respec tivel y. I t was higher in thejuices than in their cakes.5- Albumins were the first maj or protein for juice anddehydrated carrot haulm and cauliflower leaves [(47.82& 47.04) and (49.69 & 41.96) for protein content,respectively], while the globulins were the secondmajor protein [(19 .•06 & 18.90%) and (17.98 & 13.87%)for protein, respectively].According to the chemical composition of testedvegetable wastes, carrot halum and .’ cauliflower leaves werechosen for preparing leaf protein concentrates (LPC), whilewatermelon peels and artichoke bracts were used for pectinextraction. The watermelon juice, supernatant carrot haulm,supernatant cauliflower leaves, hydrolyzed cake of bothcarrot haulm and cauliflower to produce single cell protein(SCP).B) Production of leaf protein CODceatrates (LPC):1- Different methods based on precipitation or extractionof existent proteins of carrot haulm and cauliflowerleaves ·were eva·luated from.- th.e· point· of theirefficiency and the characteristics of the resultantLPC. Methods based on precipitating protein fromthe eIpressed juices of carrot haulm and cauliflowerleaves included various techniques such as different-1al heat (53° & BDOC) (RP- & UNF-), polyanion1cflocculants (FP-) and acid precipitation (AP-).Methods based on extraction of protein from thechopped materials of carrot haulm and cauliflowerleaves included extraction with NaOH (EM-NaOH) andNaCI (EM-NaCI) solutions.2- Both precipitation and extraction methods resultedin comparable protein recovery data and differencesamong each method under these two general methodswere observed. For example, in case of carrot haulmLPC, maximum total yield (CRL-CYT) was attained usingalkali (EM-NaOH) method (81.20% for EM-NaOH vs. 73.50and 70.091 for ml’F- and HP- methods, repectively).In case of cauliflower leaves LPC maximum total yieldwas attained also using alkali method (84.09% forEM-NaOH vs. 78.98 and 69.89 for UNF- and HP- methodsrespectively.3- Che.ieal eo.position of LPCThe chemical composition, of all LPC, prepared bydifferent methods from carrot haulm and cauliflowerleaves, was respectively, as follows:Moisture content ranged from 6.63 to 12.0%. Thehighest moisture content was for CHL-LPC-FP of carrothaulm, while the lowest moisture eontent was forCYT-LPC-FP cauliflower leaves.Protein content ranged from 36.15 to 53.65% and from34.53 to 67.28%, on dry basis.Ether ex tract content ranged from 3.85 to 8.12 andfrom 1.62 to 8.93X, on dry basis.Ash c6ntent ranged from 7.66 to 22.05% and from 6.37to 21.18%, on dry basis.Crude fiber content for ranged from 2.08 to 8.28%and from 1.56 to 7.62%, on dry basis.Total sugars content ranged from 1.01 to 9.10% andfrom 3.16 to 15.98%, on dry basis.4- Characteristicsof~:- CHL-LPC characterized by lower total protein contentand total sugar, and higher ash, ether ex trac t andcrude fiber contents than the corresponding CYT-LPG.- Proteins of all CHL- and CYT-LPC of. the. two sourcesdiffered with respect to their solubilities at different pH values. However, CYT-LPC seemed to be moresoluble than the CHL-LPC regardless of the sourceof LPC.- UNF-, CHL-LPC-HP and CYT-LPC-HP exhibited the lowestsolubilities at pH values 2-10 especially at pH 2and above 7, where all other LPC showed superiorsolubilities (of above 50%). However, LPC-HP hadsolubilities of not less than 19.71% at pH 10 redgardlessof LPC source.- Protein classes of LPC, in general, (regardless ofthe source), UNF- and CRL-LPC proteins were character-ized by having albumins as the first maj or proteinand having higher portion of insoluble fraction tothe corresponding CYT-LPC. On the other hand, CYTLPCproteins were characterized by having, glutei insas the first major protein, and albumins as the secondand also by having low portion of insoluble proteinfraction.- The ion-exchange chromatographic analysis revealedthe presence of 16 proteineous amino acid in LPCof both carrot ha~lm and cauliflower leaves.- Acidic amino acids constituted high portion of proteinin all the tested LPC t where they ranged from 26.13to 29.21 and from 17.85 to 23.08 g/16 g N in LPCof carrot haulm and cauliflower leaves, respectively.The neutral amino acids comprised the second maj orpart of the total amino acids.- CYT-LPC had the hi.ghest content in methionine thanCHL-LPC (2.32 and 1.34 g/16 g N) in CYT-LPC of carrothaulm and cauliflower leaves, respectiYely~The amino acid pat.tern of many of the tested LPCwas competetive with many good quality animal proteinssuch as meat protein having a good level -of theessential amino acids compared with the FAO referencepattern.- The obtained LPC varied greatl,. from the point ofmineral availability. Mineral elements varied inLPC according to the source and method of extraction.- It seems that consumption as small as about lessthan 100 g of each carrot haulm and cauliflower leavesLPC preparations would satisfy the daily recommendedallowance and in turn, req ui rements of Mg. Ca. Cu ,Zn and” Fe.C) SiD81e cell proteiD (SCP) productioD:Production of SCP 1:lyusing fungal growth (Aspergillusniger) and yeastal growth (Saccharomyces cerevisiae) on:watermelon juice. supernatant carrot baulm. supernatantcauliflower leaves, hydrolyzed cake of carrot haulm andof cauliflower leaves.1- Increasing the incubation period intreased the consumedsugar and total yield for different substrates by usingfungi and yeast.2- The protein content andcase of using waterDlelonother substrates, wh4:!therprotein yield were higher injuice as a medium. than theby the use of fungi or byyeast.3- Yield coefficient percentage was higher in case of usingfungi than using yeast for all substrates. while proteinyield was hi~her in case of using yeast than using fungi.4- Moisture, crude protein and ash contents were lowerwhile ether extract lIrashigher in SCP yielded by fUDgithan that yielded by Jeast.5- Amino acids content was higher in SCP produced by fungi(88.74 g/16 g N) than in that produced by yeast (72.51g/16 g~N).6- The first limiting amtno acid for SCP yielded by usingboth fungi and yeast was methionine. The second limitingfor SCP produced by f ung d was threonine Ivaline in SCP produced by yeast.7- Nucleic acid content was higher in SCP yielded by yeastwhile it was(16.28-18.05 8/100 g protein) than in that yielded byfungi (1.98-2.28 g/100 g protein).8- Mineral content of Scp yielded by fungi was higher inMg, P, [ and Zn, whi Le the SCP yielded by yeast washigher in Ca, Na, Fe, Mn and Cu. ”D) Pectin production:1- Total pectin content in watermelon peels was higherthan in the artichoke brac ts (11.47 and 7.83%, ondry basis, respectively).2- Pectin soluble in ammonium oxalate was the majorpart of pectin in both artichoke bracts and watermelonpeels (51.85 and 55.01%, respectively).3- The yield of pectin increased with increasing ammoniumoxalate concentrati.on and also, with inc,reasingte.perature for both artichoke bracts and watermelonpeels.4- The pectin extracted from watermelon peels was higherin ash, acetyl, reducing power and AGA (anhydrousgalactourinic acid) contents, while was lower inthe methoxyl as compared with commercial pectin.S- Physical propertielil of pectin extracted from watermelonwas nearly similar to properties of commercialpectin.