Lactic Acid Bacteria as A Bio Preservative: Importance and Production

Biopreservation is the method of employing natural microflora and their antimicrobial compounds to extend the storage life and improve the safety of foods. Streptococcus lactis was the first pure strain of lactic acid bacteria which was isolated from milk by Liszt. He named it bacterium lactis. Lactic acid bacteria are gram-positive, acid-tolerant, have low Guanine-Cytosine content and are generally non-sporulating, non-respiring, either spherical cocci or rod-shaped bacilli bacteria that share most of them their metabolic and physiological characteristics. These bacteria are mostly present in decomposing plants and milk products. They have an increased tolerance to acidity. Most species are incapable of respiration and therefore media used for lactic acid bacteria include a carbohydrate source. At the end of carbohydrate fermentation, these bacteria give out lactic acid as a major end product. The review focuses on the process of lactic acid production by lactic acid bacteria and its expanding importance in a variety of disciplines. Keywords: Lactic acid bacteria, bio preservative, food, microflora

Fermentation and Extrusion effects on Nutritional and Organoleptic Compositions of Unripe Plantain and Pigeon Pea Blends

This research investigated effects of fermentation and extrusion on unripe plantain and pigeon pea blends. The samples were blended and prepared in three combinations (A=100g unripe plantain; B= 70g unripe plantain: 30g pigeon pea; C= 50g unripe plantain: 50g pigeon pea) and sectioned into four group (i.e. group 1 = preconditioned and fermented; group 2 = extruded; group three = fermented and extruded; and group 4 = unfermented/unextruded). Semi-solid state fermentation method was employed to ferment the blended samples for 96 hours. The physicochemical parameters (i.e pH, temperature and total titratable acidity) of these fermented samples were evaluated. The total microbial counts include; 9 bacteria, 2 yeasts and 4 molds were isolated and identified as; Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc mesenteroides, Lactobacillus mali, Streptococcus lactis, Saccharomyces cerevisiae, Candida utilis, Aspergillus niger, Aspergillus fumigatus, Aspergillus candidus, and Mucor hiemalis. There were significant variations in the values of pH and total titratable acidity (TTA) during fermentation. This was also same for the proximate contents of the fermented and extruded flour blends when contrasted with the raw flour blends. The fermented unextruded group 1 (11.73±0.01%) has the highest moisture contents and least in the raw sample B (6.34±0.00%). The raw flour blends protein content increased from 2.57±0.03 to 10.17±0.00% and from 2.58±0.02 to 16.27±0.01% in the fermented extruded blends. The carbohydrate content in the raw flour blends was highest (67.97±0.02 to 74.32±0.00%) and least in fermented unextruded samples (38.28±0.01 to 62.72±0.01%). The fat content was highest in the fermented unextruded blends (2.52±0.01 to 6.33±0.00%) and least in raw blends (1.33±0.02 to 2.01±0.02%). The sensory evaluation of the samples showed a good preference for fermented-extruded samples. Findings from this research have established that fermented and extruded unripe plantain and pigeon pea blend enhanced nutritional value of food.

Microbial Fermentation of Water Melon (Citurullus lanatus) Seeds for Bioethanol Production

Watermelon (Citrullus lanatus) is a vine-like flowering originally from Southern Africa. The microbial fermentation of watermelon seeds for me production of bioethanol was investigated. The seeds were washed dried and grounded into powder. The seed powder was then fermented for bioethanol production and the microorganisms responsible for the fermentation were isolated and characterized. Bioethanol was distilled from the fermentation. The distilled bioethanol was subjected to comparative analysis with ’the conventional ethanol. Proximate analysis of the grinded seed was carried out before and after fermentation. The organisms responsible for fermentation were identified as Lactobacillus bulgaricus, Bacillus cereus, Streptococcus lactis, Staphylococcus aureus, Enterococcus sp, Micrococcus spp, Staphylococcus epidermidis, Fusarium oxysporium, Mucor mucedo, Penicillium notatum, Saccharomyces cerevisiae, Aspergillus fumigatus and Aspergillus niger. There was an increase in the protein content of the seed from 4.269% in the unfermented to 10.031% in the fermented. While carbohydrate reduced from 70.523% in the unfermented to 50.149% in the fermented seed. Fat content increased as well as crude fibre content. The distilled bioethanol boils at 78.4% and as a melting point of -112°C at 15°C. The refractive index was 1.360 and the flash point was 12°C. It burns with blue flame. Considering the comparison between the bioethanol produced from Citrullus lanatus seeds with the conventional ethanol, it can be used as an alternative source of biofuel.

Impact of Erodium moschatum (L.) L.'Hér. extracts against some bacteria and fungi species

The effectiveness of Erodium moschatum extracts (ethanol and methanol, water) were tested against pathogenic bacteria (two gram positive: Staphylococcus aureus and Streptococcus lactis and two gram negative: Escherichia coli and Proteus mirabilis) and four pathogenic fungi (Microsprum canis, Trichophyton mentagrophytes, Pencillium chrysogenum and Fusarium oxysporeum). Tannins, flavonoid and glycoside contents were studied by using HPLC technique and their antimicrobial activities were examined. The results showed the extracts efficacy on the tested microbes in which the ethanol with 11.11mm methanol with 11.22mm diameter were the most effective against the studied bacteria compared with the rest of the studied extracts, either in the fungi it was found that the studied extracts did not have significant differences in their effectiveness against the tested fungi, the results seemed that there are a difference in the concentration of studied active compounds according to the environment (geographical locations) and the difference in the plant parts, rutin showed the highest concentration in the entire plant (Sulaymaniyah) at concentration 22.92ppm compared to the rest of the compounds and Saladin locality and the studied plant part.

Identifikasi Uji Kemampuan Hidrolisis Lemak Dan Penentuan Indeks Zona Bening Asam Laktat Pada Bakteri Dalam Wadi Makanan Traditional Kalimantan Tengah

Wadi is a sort of fermented fish product from Dayak tribe in Central Kalimantan. Wadi is made with the addition of lumu, sugar, and salt, and fermented for 7-10 x 24 hours. During the fermentation process, there are microflora from fish, and microflora from lumu that play a role in fermentation process. Some species of bacteria that play a role in the wadi fermentation process are lipolytic bacteria and Lactic Acid Bacteria (LAB). This research aims to: (1) identify the species of lipolytic bacteria and LAB that present in the wadi, (2) determine the lipid hydrolysis index and lactic acid clearance zone index of lipolytic bacteria and LAB that present in the wadi, and (3) determine the species of lipolytic bacteria and LAB which have highest ability to hydrolyze lipid and have the highest ability to produce lactic acid based on lipid hydrolysis index and lactic acid clearance zone index. The results showed that, (1) there are four species of lipolytic bacteria and LAB present in wadi: Lactobacillus coryniformis, Lactobacillus casei, Nitrococcus mobilis and Streptococcus lactis; (2) the four species of bacteria have different lipid hydrolysis index and lactic acid clearance zone index which are Lactobacillus coryniformis has a lipid hydrolysis index of 1.63 and lactic acid clearance zone index of 3.31; Lactobacillus casei has index of 1.94 and 3.96; Streptococcus lactis has index of 1.51 and 1.54 and Nitrococcus mobilis has index of 0.98 and 1.52; (3) Lactobacillus casei is a species of lipolytic bacteria and LAB which has the highest ability to hydrolyze lipid and to produce the highest lactic acid based on the lipid hydrolysis index and lactic acid clearance zone index, which are 1.94 and 3.96. Keywords: lipolitic bacteria, LAB, lipid hydrolysis index, lactic acid clearance zone, wadi.