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YEAST IN FOOD TECHNOLOGY: Overview and Current Development Lilis Nuraida Southeast Asian Food and Agriculture Science & Technology Center and Departement of Food Science and Technology Bogor Agricultural University - Indonesia Yeast Technology in Food Industry Jakarta September 4, 2007 YEAST Unicellular Eukaryotes Yeast Technology in Food Industry Jakarta September 4, 2007 1 Outline • History, development and application of yeast • Technological function of yeast and yeast preparation • Yeast starter culture • Production Process of Baker’s Baker s Yeast • Yeast Derived Products: Type, function and production Yeast Technology in Food Industry Jakarta September 4, 2007 HISTORY AND DEVELOPMENT OF YEAST First approved genetically engineered wine yeast, brewer’s yeast, baker’s yeast S. cerevisiae’s genome was the first eukaryote genome fully sequenced Improvement of industrial yeast strain Yeast taxonomy study Yeast observed in malt, named Saccharomyces cerevisiae Late 1600s 2000-6000 BC Late 1800s End 20th and 1st ys 21st Century Late 1900s Isolation of single yeast and employement of pure yeast starter cultures for beer and wine Early 1800s Microscopic appearance of yeast (van Leeuwenhoek, 1685) Fortuitous use of yeast in wine making (Caucasia), beer brewing (Sumeria, Babylonia) and dough leavening (Egypt) Verstrepen et al. 2006 Yeast Technology in Food Industry Jakarta September 4, 2007 2 Saccharomyces yeasts • Mankind’s oldest domesticated microorganism • Considered to be the best studied and most used yeast: – 30 million tons of wine p.a. – 60 million tons of beer p.a. – 600,000 tons of baker yeast p.a. – 800,000 tons of single cell protein p.a. Verstrepen et al. 2006 Yeast Technology in Food Industry Jakarta September 4, 2007 The road of discovery and application of yeast Synthetic Biology Systems y Biology gy Molecular Biology Genetics Biochemistry • • • Prospect of the synthesis of entire genomes for construction of “ideal” industrial yeast Exploitation of biological complexity of yeast strain improvement for example to optimise yeast cell process. Metabolic engineering of yeast by directed genetic modifications and reconstruction to improve performance of industrial strains • Microbiology • • • • Genetics engineering g g of yyeast by yg gene cloning g and trnasformation of specific genes for a new desirav=ble characteristics Genetics breeding Mutagenesis and selection Clonal selection Isolation and Identification Adapted from Verstrepen et al. 2006 Yeast Technology in Food Industry Jakarta September 4, 2007 3 Technological Function of Yeast • Dough Leavening (baker’s yeast) • Brewing (brewer’s yeast) • Distilled alcohol beverages fermentation (distiller’s yeast) • Wine fermentation (wine yeast) • Other alcoholic fermentation (ragi) – Indonesia: I d i ttape, brem b • Dairy fermentation (kefir grain) • Soy fermentation (soy sauce, tauco) Yeast Technology in Food Industry Jakarta September 4, 2007 Desirable properties of Baker’s Yeast • S. cerevisiae: – Rapid maltose fermenting ability (lean dough yeast) – Improved osmotolerance (sweet dough yeast) – Rapid fermentation kinetics – Freeze/thaw tolerance – Substrate metabolism: • Melibiose utilising ability (beet molasses as substrate) • Lactose utilising ability (whey as substrate) Yeast Technology in Food Industry Jakarta September 4, 2007 4 Desirable properties of Brewer’s Yeast • Bottom fermentation process (ale) – S.cerevisiae • Top fermentation process (lager) – S. uvarum • Carbohydrate utilization – Increase metabolism of maltose and maltotriose in malt wort – Ferment dextrin and starch • Efficiency and low calorie (light) beer Yeast Technology in Food Industry Jakarta September 4, 2007 Desirable properties of Distiller’s Yeast • Natural fermentation: any number of species may be involved • Controlled fermentation: S.cerevisiae – Very alcoholic tolerant and gives a good yield – Ferments rapidly y – Good flavor production Yeast Technology in Food Industry Jakarta September 4, 2007 5 Wine Yeast • Controlled fermentation started in 20th century • Natural fermentation involves different yeast species such grow succesively at initial. – In the most active fermentation stage to end of fermentation: Saccharomyces cerevisiae • Desirable characteristics: – Rapid fermentation rate – Tolerance to SO2 Yeast Technology in Food Industry Jakarta September 4, 2007 Yeast Preparation based on Activity • Yeasts are available in several forms, and are classified l ifi d on th the b basis i off th their i activity. ti it – Active yeasts include: • Baker’s yeast • Brewer’s yeast • Yeasts for alcoholic beverages – Inactive yeasts, such as: • Dried brewer’s yeast • Primary- grown yeasts Yeast Technology in Food Industry Jakarta September 4, 2007 6 Yeast Starter Culture Preparation • Yeast Cream (18-20% solid) • Compressed yeast (27-32% solid) • Dry yeast (8% moisture) – Active Dry Yeast – Instant Dry Yeast Perishable, kept refrigerated Shelf-life up to 2 y in suitable packaging • Traditional ad t o a d dry y yeast ((ragi) ag ) • Kefir grain Yeast Technology in Food Industry Jakarta September 4, 2007 Storage Stability of Active Dry Baker’s Yeast in Variuos Atmosphere Atmosphere Residual Activity (%)*) Nitrogen 79.5 Carbon dioxide 81.9 Carbon monoxide 85.2 Argon 80.7 Hydrogen 88.9 Air 43 3 43.3 Vacuum 70.3 *) after storage for 3 d at 55oC Hill, 1987 Yeast Technology in Food Industry Jakarta September 4, 2007 7 Ragi and Kefir grain • Kefir grain • Ragi – Mixed yeast culture – Present together with amylolytic molds – Mixed Mi d yeastt culture lt – Present together with lactic acid bacteria Yeast Technology in Food Industry Jakarta September 4, 2007 Yeast Biomass • B Baker’s k ’ Y Yeast • Brewer’s Yeast • Single Cell Protein Used for food Used in food is limited Mainly for feed Yeast Technology in Food Industry Jakarta September 4, 2007 8 Production Process of Baker’s Yeast Raw Materials FILTRATION FERMENTATION STAGES Flask fermentation BLENDING Pure culture fermentation Intermediate fermentation EXTRUSION AND CUTTING DRYING: tunnel, fluid bed Compressed Yeast Dried Yeast Stock fermentation Pitch fermentation Trade fermentation PACKAGING Yeast Technology in Food Industry Jakarta September 4, 2007 Baker’s yeast fermentation • Substrate: – Molasses: beet and/or cane – Other: whey • Fermentation condition: – Aerobic Yeast Technology in Food Industry Jakarta September 4, 2007 9 Processing aids and additives to improve activity of Dry Yeast • Added to yeast cream or press cake prior to drying: – Swelling agent: • Methyl cellulose or carboxymethyl cellulose (1-2% of yeast solid) (Langejan, 1980) – To reduce solid leaching • Monoglycerides, gy soya y lecithin, g glycerol y p polyesters y and sorbitan esters (Hill, 1987) – To improve storage in air: • Addition antioxidant Yeast Technology in Food Industry Jakarta September 4, 2007 Yeast-Derived Products • Yeast Extract • Yeast Autolysates Contains guanosine 5’monophosphate (GMP), ionosine 5’monophosphate (IMP), glutamic acid • Application: – Flavoring g agent g in soup, p, sauces,, g gravies,, stew, snack food etc. – Main component of savoury spreads: Vegemite and Marmite Yeast Technology in Food Industry Jakarta September 4, 2007 10 Yeast Extract Components • • • • • • • Amino acids Peptides Nucleotides Proteins Carbohydrates Vitamins Flavor compounds Yeast Technology in Food Industry Jakarta September 4, 2007 Product definition • Yeast Extract: – Yeast extract comprises the water soluble components of the yeast cell, the composiiton of which is primarily amino-acids, peptides, carbohydrates and salts. Yeast extract is produced through the hydrolyses of peptide bonds by the naturally occurring enzymes present in edible yeast or by the addition of food grade enzymes The Food Chemical Codex Yeast Technology in Food Industry Jakarta September 4, 2007 11 Product definition • Yeast Autolysates/Autolysed yeast: – Autolysed yeast is the concentrated, concentrated not extracted, partially soluble digest obtained from food-grade yeast. Solubilisation is accomplisehd by enzyme hydrolysis or autolysis of yeast cells. Autolysed yeast contains both soluble and insoluble components derived from the whole yeast cells. The Food Chemical Codex Yeast Technology in Food Industry Jakarta September 4, 2007 Composition Yeast Extract Yeast Autolysate • Protein content: 5075% • Total carbohydrate: 413% p content: very y • Lipid little • Protein content: 5069% • Total carbohydrate content: 15-25% • Lipid content: 3-10% Yeast Technology in Food Industry Jakarta September 4, 2007 12 Preparation of Yeast Extract • Requires disruption of cell walls: – Autolysis by endogenous enzymes*) – Plasmolysis: modified autolyses in the presence of accelerator, i.e. salt or organic solvent – Mechanical desruption p – Hydrolysis by acid or by exogenous enzymes *)practical on industrial scale Yeast Technology in Food Industry Jakarta September 4, 2007 Production Process of Yeast Extract Absent in production of yeast autolysate Yeast cream Clarification Plasmolyses Concentration Autolyses y Liquid: 50-65% dry matters Paste: 70-80% 70 80% dry matters Pasteurisation Packed in pails, drums Spray, roller drying Yeast Technology in Food Industry Jakarta September 4, 2007 13 Source of yeast cream • Conventional: – Baker’s Yeast – Brewer’s Yeast • Alternative: • Candida utilis • Kluyveromyces marxianus Enriched yeast extract in amino acid cystein produced through the application of GE-yeast to over express and over produce the yeast cystein-rich protein metallothionein (Stam et al., 2000) Yeast Technology in Food Industry Jakarta September 4, 2007 Condition for Yeast Extract Production Steps Autolyses and Plasmolyses Pasteurisation Concentration Condition 55 oC for 24 h, pH 5.5 1st : 70oC for 15 h 2nd: 70-75oC for 2-5 h (after clarification) Temperature <55oC Adapted from Biocatalyst Ltd Yeast Technology in Food Industry Jakarta September 4, 2007 14 Common problem encountered in yeast extract production Problem Solution*) Enzyme not working Ensure no direct heat Low yield autolysis Check pH and temperature of slurry at each stage Extend autolyses time Add protease Over heat Add protease Clarification problems caused by Add glucanase insoluble glucans Keep final temperature <55oC during final evaporation Treatment with protease followed by nuclease resulted in the highest 5’-GMP (Chae et al., 2001) Burnt flavor *)Adapted from Biocatalyst Ltd Yeast Technology in Food Industry Jakarta September 4, 2007 Other yeast-derived products • Colorants – Pigmented yeasts such as Rhodotorula, Phodospondium, Cryptococcus, Sporidiobolus, Sporobolomyces, GESaccharomyces, Candida • Yeast Polysaccharides: – Food application and nutraceutical potential – Potential species S. S cerevisiae, cerevisiae Pichia holstii holstii, Hansenula sp, Candidia, Rhodotorula • Yeast Enzymes Yeast Technology in Food Industry Jakarta September 4, 2007 15 Conclusion and future outlook • The economic important of yeast to the food industries continues to outweigh all other commercial uses of yeast • Modification and tailoring yeast for an increasing array of application provide added promise for the application of yeast in the food industries Yeast Technology in Food Industry Jakarta September 4, 2007 Thank you Further information: [email protected] Http://www.seafast.ipb.ac.id p p Yeast Technology in Food Industry Jakarta September 4, 2007 16