E. SELMER-OLSEN, S.-E. BIRKELAND AND T. SO šR HA U G. 1999. When lactic acid bacteria are used industrially as fermentation starters it is important to obtain stable and highly viable bacterial cultures. Six strains of Lactobacillus encapsulated in Ca-alginate gel beads were investigated to determine whether dehydration, storage and rehydration may inflict injury. A negative relationship between leakage of lactate dehydrogenase and survival rates was found. Mesophilic lactobacilli showed only negligible leakage compared with thermophilic strains when dehydrated at 30°C to a level of 0·11 g H 2 0 (g dry wt). The choice of an appropriate suspending medium to be introduced before drying was therefore very important for thermophilic lactobacilli in order to increase the survival rates during dehydration, storage and rehydration. The osmoregulatory solutes tested were adonitol, betaine, glycerol and reconstituted non-fat milk solids (NFMS). Less injury was inflected during dehydration for Lactobacillus helveticus with adonitol, glycerol and NFMS. Survival rates for the strains subjected to immobilization, dehydration, storage and rehydration varied with the strain and the protective solute when fluidized-bed drying was used at 5°C to a level as high as 0·34 g H 2 0 (g dry wt) −1. Non-fat milk solids gave the best protection for thermophilic lactobacilli, while adonitol and NFMS were best for mesophilic lactobacilli.

Lactobacillus helveticus CNRZ 303 entrapped in Ca-alginate gel beads was investigated for improved survival and stability during fluidized-bed drying, storage and rehydration. Addition of protective solutes was very important. Studies of the conditions showed that inactivation of entrapped L. helveticus started when the water content exceeded 0.3-0.4 g H2O (g dry wt)-1 for adonitol, glycerol and reconstituted non fat milk solids (NFSM). With Ringer's solution (control) and betaine, the fall in viability was evident above 1 g H2O (g dry wt)-1. Drying down to 0.2 g H2O (g dry wt)-1 required the removal of 98.5-98.9% of the water. The best survival rate with the least injured cells among survivors was experienced with adonitol and NFMS, respectively, 71% and 57% (compared to the initial) immediately after dehydration. Adonitol and NFMS were also best for survival during storage. The highest cell recovery was obtained by rehydrating the cells in cheese whey permeate between 20-30 degrees C done at pH 6.0-7.0, satisfying the demands for cell survival, repair and slow swelling (adaptions).

Recovery of proteins and fats from dairy wastewater has two advantages: the recovery process results in a pretreatment of wastewater prior to discharge to municipal sewers; and the recovered sludge can be used as a food additive. Carboxy Methyl Cellulose (CMC) is commonly used for the treatment of dairy wastewater after reducing the wastewater to pH 4.2. A novel application of a non-toxic cationic biopolymer – chitosan – is evaluated as a substitute for CMC. The results indicate that chitosan can achieve results similar to the CMC process even at pH as high as 5.3. Thus, the novel method can save up to 50 % of pH-adjusting chemicals requires for both for acidification and neutralisation. The process sludge contains valuable components which have been evaluated and found to be suitable as a food additive. A stable demand for chitosan is also expected to solve the existing shrimp-shell waste disposal problems along the west and north Norwegian coasts. The process is found to be both environmentally and economically attractive for all partners.

BackgroundCow milk is a natural source of the cis 9, trans 11 isomer of conjugated linoleic acid (c9,t11-CLA) and trans vaccenic acid (VA). These fatty acids may be considered as functional foods, and the concentration in milk can be increased by e.g. sunflower oil supplementation to the dairy cow feed.The objective of this study was to compare the effects of regular butter with a special butter naturally enriched in c9,t11-CLA and VA on plasma lipids in female growing pigs. The experimental period lasted for three weeks and the two diets provided daily either 5.0 g c9,t11-CLA plus 15.1 g VA or 1.3 g c9,t11-CLA plus 3.6 g VA.ResultsThe serum concentrations of c9,t11-CLA, VA and alpha-linolenic acid were increased and myristic (14:0) and palmitic acid (16:0) were reduced in the pigs fed the CLA+VA-rich butter-diet compared to regular butter, but no differences in plasma concentrations of triacylglycerol, cholesterol, HDL-cholesterol, LDL-cholesterol, LDL particle size distribution or total cholesterol/HDL cholesterol were observed among the two dietary treatment groups.ConclusionGrowing pigs fed diets containing butter naturally enriched in about 20 g c9,t11-CLA plus VA daily for three weeks, had increased serum concentrations of alpha-linolenic acid and decreased myristic and palmitic acid compared to pigs fed regular butter, implying a potential benefit of the CLA+VA butter on serum fatty acid composition. Butter enriched in CLA+VA does not appear to have significant effect on the plasma lipoprotein profile in pigs.

: A continuous process for treatment of dairy wastewater with immobilized lactic acid bacteria has been demonstrated at pilot scale. A strain of L actobacillus plantarum was selected on the basis of a high conversion rate of lactose at low pH, a high affinity of lactose at low concentrations, and the ability to retain activity for a long time immobilized in alginate beads. Lactose was converted to lactic acid, which lowered the pH and precipitated milk proteins. The proteins were separated together with milk fat by Ñotation with carboxy methyl cellulose (CMC) or chitosan and gave a solid phase of approx. 10% dry matter (23% protein and 68% fat). The total chemical oxygen demand removed (COD t ) varied from 65 to 78% for CMC and 49 to 82% for chitosan. The precipitated material was used as a feed supplement for pigs to provide up to 30% of the total energy intake. No adverse e †ects on the pigÏs performance were observed. The energy feed value of the precipitate was estimated to be 2É0 feed units (FUs) per kg dry matter.