0.05 0.15 0.25 y = 0.275x - 0.0089 BIO-CULTURAL AND AGRICULTURAL SCIENCES Code

a b Figure 3. a Relations of lactic acid bacteria with the water content during storage for determination of critical moisture content Mc, b sorption curve isotermis dried cultures L. rhamnosus R21 for the determination of the equilibrium moisture content Me. Equilibrium moisture content Me is determined by a linear equation of sorption curve isotermis dried culture on the relationship between water content with water activity of dried cultures were measured using aw meter. Isotermis sorption curve slope values b were determined in the linear region of the curve of the relationship between water content with water activity Arpah 2001. Slope value of dried cultures L. rhamnosus R21 is 0.2789 from the calculation of the ratio between the difference in initial moisture content and moisture content critical to the difference between the value of initial water activity with the activity of water at the critical moisture content is reached. Of linear equations in Figure 4b obtained equilibrium moisture content Me on storage at 75 RH bk 19.75 or 0.1975 g H 2 Og solids, while storage at 80 RH obtained the equilibrium moisture content of 21.11 bk or 0.2111 g H 2 Og solids. Saturated water vapor pressure Po of storage conditions on the shelf life determination is the saturated vapor pressure at 75 RH and a temperature of 30 o C in the amount of 31.824 mmHg Labuza et al. 1984. Packaging used in determining the shelf life of dried cultures are usually aluminum foil packaging, but can also use aluminum foil packaging are plastic coated. The use of plastics for packaging is quite interesting because of its favorable properties such as easy to set up, has a high adaptability of the product, such as non-corrosive metal containers, as well as easy handling Syarief et al. 1989. According to Latif 1999 packaging permeability kx for PE poliethylene = 0.169 g H 2 O m 2 .mmHghari; PVC polivinylchloride = 0.544 g H 2 Om 2 .mmHghari, while aluminum foil laminated with plastics PE = 0.013 g H 2 Om 2 .mmHghari Histifarina 2002. Calculation of shelf life of the packaged material assuming weighing 20 g wet weight 19.98 g dry weight, widely used packaging by 11 x 7 cm 2 then the ratio of surface area with heavy packs are packaged culture is at 0.0004 m 2 g . y = -1.2693x + 29.774 R 2 = 0.8393 2 4 6 8 10 12 14

0.00 0.05

0.10 0.15

0.20 0.25

m oist ure cont ent of dried cult ures g H2O g solids 2 T o ta l B A L k u ltu r k e ri n g l o g c fu g c fu g

0.9 y = 0.275x - 0.0089

R 2 = 0.9453

0.00 0.05

0.10 0.15

0.20 0.25

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 Water activity a

w m o is tu re c o n te n t o f d ri e d c u lt u re s g H 2 O g s o li d s Based on the equation parameters shelf has been described above, the shelf life of dried cultures can be determined. If fluctuations in humidity at room temperature between 75 to 80 with initial moisture content dried cultures L. rhamnosus R21 at 2.17 bk according to research, the shelf life of dried culture with a laminated aluminum foil packaging with plastic PE can reach 5.10 to 5.86 years on a slope value of 1 and 5.10 – 5.88 years on the value of slope 2. Results shelf life of dried cultures calculation using the equation Labuza 1982, with a wide range of packaging on the storage RH 75 and 80 to 30 o C storage temperature can be seen in Table 1. Table 1 Estimation of shelf life of dried cultures L. rhamnosus R21 at RH 75 and 80; Temperature 30 o C Type of packaging Permeability packaging kx Shelf life years RH 75 RH 80 Aluminium foil laminated with PE 0,013 5,86 5,10 Metallized plastic 0,018 4,23 3,68 PET 0,020 3,81 3,31 PE 0,169 0,45 0,39 PVC 0,544 0,14 0,12 Type of packaging with different permeability showed different results. The results obtained show that packing with high permeability have a shorter shelf life compared with the packaging which has a low permeability. On application by using the model Labuza 1982, the permeability of the packaging is crucial shelf dried cultures L. rhamnosus R21. Permeability relatively small package capable of inhibiting the transformation of water vapor into a storage environment with good packing so that the level of dryness in the product can be maintained long term. Based on calculations derived shelf life, packaging should be used to store dried cultures L. rhamnosus R21 is aluminum foil laminated with plastic PE with relatively low permeability compared to packaging PE polyethylene or PVC polyvinylchloride. CONCLUSION The process of freeze drying freeze drying decrease the number of lactic acid bacteria, but can still produce dried probiotic cultures with high viability. From the calculated shelf life estimation using equation Labuza 1982, found that the shelf life of dried cultures L. rhamnosus R21 stored at RH 75, temperature of 30 o C with aluminum foil packaging materials are laminated with PE for 5.86 years and 5.10 years for RH 80. From the results of this study suggest that further testing needs to be done on the properties of other probiotic dry cultures L. rhamnosus R21 that has been through the process of freeze-drying as the ability to reduce the number of pathogenic bacteria, and should also confirm