Use of Alkaline Peeling Effluents from Vegetable and Fruit Processing Operations by Neurospora sitophila.

Growth of Neurospora sitophila on alkaline effluents from rutabaga, potato, and peach processing operations was studied. Submerged fermentation at 30 C reduced COD values from 42 to 68% of initial values for peeling wastes and from 17 to 25% in rinse wastes after 4 days. This procedure for reducing COD would be of interest as a pretreatment technique for use in processing plants discharging into municipal treatment systems. The total amino acid content of potato effluent biomass was nearly quadrupled, whereas the total amino acid content of peach effluent was doubled after 1 day of fermentation.

Determination of molecular-weight distribution of chitosan by high-performance liquid chromatography.

Optimal conditions for using high-performance liquid chromatography (HPLC) in the size exclusion mode have been determined for measuring the molecular-weight (MW) distribution of chitosan samples. Physical separation according to molecular size was accomplished on the stationary phase of glass supports having controlled pore sizes ranging from 2500 to 40 A. Selection of column combinations was based on the requirements to resolve the higher MW fraction of chitosan and to give a linear calibration curve within the required MW range. The best combination of glass pore sizes and column lengths in two foot sections joined sequentially was: 2500 A (2 ft.), 1500 A (4 ft.), 550 A (6 ft.), 250 A (2 ft), 100 A (2 ft.), and 40 A (2 ft.). A loading study showed that an injection load of 500 mug, i.e. 100 mul at 5 g/l or 50 mul at 10 g/l (w/v), was the optimal load to give reproducible elution volumes, precision in quantitation, and minimum viscosity effects. The best calibration curve using defined dextran standards was obtained from the geometric mean of Mw (weight average MW) and Mn (number average MW) values and peak elution volumes. Precision in determining MW distribution of chitosan as well as dextran standards was better than 5% relative standard deviation, and the differences between these results and the manufacturer's data on the dextran standards were 6 to -17%. The MW distribution of a selected chitosan samples in 2% acetic acid thus determined was Mw = 2,055,000, Mn = 936,000, dispersity = 2.16, and the most abundant species was around 1,103,000. Analysis time for the HPLC separation was less than 20 min per sample. Chitosan is an effective coagulating agent for the treatment of food processing wastes and activated sludge from biological treatment systems. It is manufactured from chitin in shrimp and crab wastes. The rapid methods developed here for determining the MW distribution of chitosan preparations will be used to optimize the manufacturing process and guide the selection of more effective chitosan products.

Recovery and nutritional evaluation of proteinaceous solids separated from whey by coagulation with chitosan.

Chitosan, a cationic carbohydrate polymer manufactured from chitin in shrimp and crab wastes, coagulated suspended solids in cheese whey as effectively or more so than ten commercial synthetic polymers. Concentrations of suspended solids after settling were reduced over 90% by coagulation at pH 6.0 with a ratio of chitosan to suspended solids of 2.15% (1:46.5). The yield of coagulated solids was approximately 2,270 mg/liter. The proximate composition of the coagulated solids after freeze drying was 73% protein, 6% lactose, 10% ash, and 7% moisture. Without the aid of a coagulating agent, setting for 1 or 3 h reduced suspended solids by only 34% and 49%, respectively. Rat feeding studies showed nn significant differences in the protein efficiency ratio of casein, coagulated whey solids containing chitosan, and whey solids containing no polymer. These results provide evidence of utility for coagulated whey solids as a protein supplement.

Effects of chitosan--a coagulating agent for food processing wastes--in the diets of rats on growth and liver and blood composition.

Effects of feeding free chitosan to rats at graded levels up to 15 percent of the diet for eight weeks was investigated. Animals receiving diets containing 5 percent or less of chitosan grew well at comparable rates. Progressive growth reduction occurred when chitosan was increased to 10 and 15 percent of the diet and enlargement of liver and kidneys was observed only in animals receiving the highest level of dietary chitosan. Liver moisture, protein, lipid, ash, and nucleic acids; blood hemoglobin and packed cell volume; and serum total protein, albumin, ceruloplasmin and transferrin were determined. Values for these components of liver and blood were altered significantly in the animals receiving the highest level of chitosan when compared to control animals. However, in animals receiving 5 percent or less of dietary chitosan none of these measures of tissue composition was different from controls, except for liver protein concentration of rats fed the 5 percent of chitosan diet. Animal feeds containing coagulated by-products are not expected to contain over 0.2% chitosan in the total diet. No adverse effects have been observed at this level in rat feeding studies. Therefore the tolerance level for dietary chitosan appears to be well above the levels expected to be in animal feeds containing by-products recovered from food processing wastes by coagulation with chitosan.

Preparation and evaluation of two microbiological media from shrimp heads and hulls.

Two peptones were extracted from raw shrimp waste after autolytic digestion. Digests were derived from shrimp heads and shrimp hulls, both of which are by-products of the shrimp processing industry. Digests were evaluated for suitability in supporting growth of microorganisms by measuring the total cell mass produced by five genera of bacteria and five genera of fungi in broths formulated from the peptones. Comparison was made to five commercially available medium preparations and a catfish peptone. A 0.5% solution of the lyophilized shrimp head digest, heated at 121 C for 15 min, resulted in a cloudy suspension. However, the digest supported excellent growth of fungi and good growth of bacteria. A heated 0.5% solution of the hull digest was clear and supported good growth of both bacteria and fungi.

Utilization of collagenous by-products from the meat packing industry: production of single-cell protein by the continuous cultivation of Bacillus megaterium.

The conditions for continuous cultivation of Bacillus megaterium on a collagen-derived substrate (SP-100) were determined. The optimum conditions of temperature, pH, and dilution rate were 34 C, pH 7.0, and 0.25/hr, respectively. Increasing the substrate concentration in plain tap water resulted in proportional increases in the productivity of cell mass from 0.6 g per liter per hr at 1% substrate to 1.8 g per liter per hr at 10% substrate; however, the protein content of the biomass decreased from 60 to 36%, and the protein yield decreased from 91 to 50% at substrate concentrations of 1 and 10%, respectively. These effects (decreases) were reversed up to 7.5% substrate by mineral supplementation of the medium. The productivity of biomass increased from 0.6 to 1.9 per liter per hr; the protein content of the biomass, from 43 to 54%; and the protein yield, from 60 to 93%, respectively, as the substrate concentration (with mineral supplementation of the medium) was increased from 1 to 7.5%. Spent medium could be refortified and recycled as often as five times. The amino acids in the substrate protein appeared to be utilized for growth and metabolism more or less uniformly. Analysis of the B. megaterium biomass indicated considerable enrichment of the essential amino acids and reduction of proline, glycine, and hydroxyproline as compared to the collagen-derived substrate. The Protein Efficiency Ratios obtained on the collagen-derived substrate (SP-100) and on the B. megaterium biomass, expressed as percentages of the casein reference protein, were 14 and 74%, respectively. Thus, considerable improvement in nutritional value was effected by bacterial conversion of the collagen-derived substrate into single-cell protein.