Cider Apples with a kick Apples Cider Fermentation Filtration Mash Enzymation Nutrients Whether cloudy or clear, sweet or dry, there are many types of this much-loved alcoholic drink, which is created by fermenting apple juice. Regardless of whether the cider is produced on a large industrial scale or in small cider mills, the same requirements are necessary on the production processes and the final product. In order to fulfil these requirements, supporting biotechnological products are available to the producers. Enzymes increase the juice yield, active dry yeasts and yeast nutrients ensure safe alcoholic fermentation and, by using malolactic bacteria, both speedy and safe malolactic fermentation (MF) and the desired aroma of the final product can be achieved. Cider Cider was first produced in France, and quickly spread to England, Belgium, Northern Spain, Ireland, Austria and Germany. It has now been produced around the world for over 2,000 years. The variety of flavors can be attributed to the different varieties of apples and production processes. In 2013, England was Europe s largest producer of cider with 9,735,000 hl, followed by Spain (950,000 hl), France (821,000 hl) and Germany (676,000 hl). The world s largest grower of apples for cider production is France. Europe is responsible for 69 % of global cider consumption, making it the largest consumer of the drink. Africa and the Middle East consume 11% and the rest of the world consume around 20 % [AICV]. Production process The production process for cider is similar to that of fruit wine processing. First, the apples are cleaned and sorted. The subsequent crushing and pressing enables the juice to be extracted. The clear juice is fermented, filtered and bottled. In order to influence the aromatic profile, apples with a range of acidity and tannin contents are selected. England, as the world s top cider producer, distinguishes the types of flavor as sharp, bittersharp, bittersweet and sweet. To produce these flavors requires the selected varieties of apples to be developed into a blend during the production process. Only rarely is an apple variety developed separately. The blend is used to round off the taste of the tannin and sugar contents. After being harvested, apples are either processed directly, matured or are stored in a cold storage facility for several weeks. Before processing, the apples are washed. Damaged or microbiologically compromised apples are rejected. This selection is necessary to avoid off-flavors and microbiological problems in downstream production stages. After the grinding process comes the juice extraction, which uses packing presses, belt presses, hydraulic presses, pneumatic presses or decanters. Pectolytic enzymes may be used to increase the juice yield. The enzyme activity has a significant influence on the yield and the haze removal of the juice. Mash enzymation The use and effectiveness of enzymes depend on the technology used to produce the enzymes. Pectolytic enzymes are produced either by submerged fermentation or solid-state fermentation. In submerged fermentation, which is also known as liquid culture fermentation, mold (from which the enzyme is generated) is cultivated in a fermentation medium. In solid-state fermentation, which is also known as surface fermentation, microorganisms are cultivated on a basic substrate. Modern pectolytic enzymes (e.g. Panzym First Yield Enzyme) are made using a combination of two enzyme production technologies. Some of the advantages of these new mixtures of enzymes are: Increased yield of between 5 20 %, depending on the ripeness of the apples Increased use of the press capacity of between 20 50 % for consistent yields 138 July / August 2015
Increase in the unpressurized run-off juice percentage Improved juice clarification Optimized downstream filtration The dosage of the pectolytic enzyme depends on the quality of the apples. Fresh fruit with between 40 80 ml/t mash can be processed in a temperature range of between 20 25 C. The holding time is from 0.5 to a maximum of 1.5 hours. For stored fruit, the enzyme dosage needs to be increased to 100 to 200 ml/t. The temperature range and holding time remain the same. Figures 1 and 2 show the yield of enzyme-treated apple mash on two processing days during the harvesting season on an industrial scale. On the first processing day, on average 6.909 kg of mash per hour was processed, with a yield 88.37 % (see figure 1). On the second day, the average amount of mash processed was 7.220 kg per hour and the average yield was 88.00 % (see figure 2). During this time period, the various quantities of mash are a result of the different quantities of apples delivered by farmers. Figure 1: Yield of enzyme-treated apple mash without secondary extraction on the first processing day The above results demonstrate that a constant juice yield can be achieved regardless of the volume of mash processed or natural variations in the quality of the apples. The key to continuity is mash enzymation. The pecto- lytic activities of the mash enzyme and its composition of polygalacturonase, pectin methylesterase and pectin lyase from different enzyme production technologies enable the effective digestion of natural apple pectin. This gives the producers a consistently high juice yield regardless of variations in apple quality. Figure 2: Yield of enzyme-treated apple mash without secondary extraction on the second processing day After the juice has been produced, safe and complete alcoholic fermentation is required. Particularly in apple juice, the naturally occurring wild yeast Hanseniaspora uvarum is the main cause of volatile acidity (acetic acid) or ethyl acetate, which are indications of a spontaneous alcoholic fermentation that is microbiologically defective. Under the microscope, the wild yeast Hanseniaspora uvarum can easily be distinguished from the Saccharomyces cerevisae or Saccharomyces bayanus strains of active dry yeast. Wild yeast cells are lemon shaped/apiculate [Riekstina-Dolge et al.], while active dry yeast cells are round or oval shaped. Wild yeasts can be reduced by proper preliminary sedimentation of the juice or by pasteurization. Alcoholic fermentation To achieve a clean alcoholic fermentation of the apple juice requires an optimized rehydration of the Saccharomyces active dry yeast. By adding inactive yeast nutrients (e.g. SIHA SpeedFerm yeast nutrient) during the rehydration of the active dry yeast, cell vitality and the total cell count are increased (see figure 3). During alcoholic fermentation, the rehydrated yeast cells with inactive yeast nutrients are more active than non-rehydrated yeast cells without inactive nutrients, as they absorb minerals, July / August 2015 139
Figure 3: Use of inactive yeast nutrients during the rehydration of active dry yeast amino acids and vitamins and store them intracellularly. The optimized nutrient availability promotes cell proliferation and is reflected in an increase of around 10 % in the total cell count, which also raises the level of fermentation activity. Alcoholic fermentation proceeds smoothly until the end, and the danger of stuck fermentation is minimized. The effect of inactive yeast nutrients on alcoholic fermentation is reflected in the total number of active yeast cells, measured 20 minutes after rehydration. In the experiment, 20 g/hl of the active dry yeast SIHA active yeast 7 was rehydrated in an apple juice with 11 Bx at a temperature of 35 C. The control was performed without the addition of inactive yeast nutrients (threefold repetition). The variants with inactive yeast nutrients were performed at 20, 30 and 40 g/hl (see figure 4) with two repetitions each. The total cell count is determined using the Thoma counting chamber and Koch s pour plate method. In comparison to the control, the total cell count in the 20 g/hl variant with inactive yeast nutrients after being counted with the Thoma counting chamber and following the pour plate method was higher, at between 7.45E+08 and 7.30E+08 cfu/ml. After 20 minutes, the control (without the addition of inactive yeast nutrients) measured between 3.55E+08 and 6.45E+08 cfu/ml in the Thoma counting chamber. The difference between the 20 g/hl variant with inactive yeast nutrients and the control corresponds to an increase in the total cell count of between 16 48 %. The findings using the Thoma counting chamber were supported by the pour plate method. Figure 4: Comparison of the development of the total cell count (Thoma counting chamber and Koch s pour plate method) 20 minutes after rehydration with and without inactive yeast nutrients 140 July / August 2015
The increased total cell count during the rehydration forms the basis for an optimal start to the alcoholic fermentation and a more vigorous development of active dry yeasts. Another advantage is the rapid development of the cell count, which accelerates the formation of alcohol, which in turn suppresses the wild yeasts. This ensures that alcoholic fermentation takes place quickly and safely and by the end has transformed all of the sugars into alcohol. More Profit from Non-Stop Output Malolactic fermentation MF is a common and widely used method of breaking down L-Malic acid into L-Lactic acid. This biological acid reduction is associated with a rise in ph and is gentle and maintains the aroma. MF reduces the sour taste and the metabolic byproduct diacetyl can add a flavor of MF to the overall sensory picture. Another function of MF is acidity stabilization. The L-Lactic acid formed cannot be metabolized by microorganisms, thereby stabilizing the microbiological acidity. Figure 5: Breakdown processes during MF In practice, undesirable spontaneous MF often occurs during or after alcoholic fermentation. This has the consequence that an increased amount of acetic acid or acetolactate also forms during the breakdown of L-Malic acid into L-Lactic acid [Jarvis]. This is an indication of cider spoilage. Spontaneous MF is initiated through Lactobacilli [Jarvis]. The consequences are, in addition to the formation of acetic acid, increased levels of L-Lactic acid, D-Lactic acid and biogenic amines, which results in off-flavors in the cider. To avoid this undesirable development, planned MF using Oenococcus oeni malolactic bacteria is advisable. Targeted inoculation after alcoholic fermentation ensures the controlled breakdown of L-Malic acid into L-Lactic acid without significantly increasing the volatile acidity [Zhao H, et al.]. In addition, depending on the malolactic bacteria culture used, citric acid can be converted into diacetyl (see figure 5). Maximum availability with the ultimate in output: the new gmaster CF decanter for profitable processing of fruit juice. GEA Westfalia Separator Group GmbH Werner-Habig-Straße 1, 59302 Oelde, Germany Phone: +49 2522 77-0, Fax: +49 2522 77-2089 ws.info@gea.com, www.gea.com July / August 2015 engineering for a better world 141 BE-03-004
potential of the depth filter sheet to be exhausted, all microorganisms detrimental to the beverage to be removed and an optimal product stability to be achieved. Summary BECO depth filter sheets The formation of diacetyl is closely linked to the growth of Oenococcus oeni malolactic bacteria and the breakdown of malic acid. Citrate-positive malolactic bacteria (e.g. Viniflora CH11) absorb citric acid into their metabolism and begin to break down when around half of the L-Malic acid has been metabolized. High concentrations of citrates lead to high concentrations of diacetyl in the finished drink. In terms of the senses, diacetyl is described as having a buttery, lactic taste. This aroma masks the fruit aromas and may be perceived as an off-flavor by the consumer. The newly selected citrate-negative malolactic bacteria cultures (e.g. Viniflora CiNe) do not absorb any citric acid into their metabolism and as such do not form diacetyl during the breakdown of L-Malic acid into L-Lactic acid. This ultimately results in the fruitiness and the typical apple aroma of cider. Filtration After MF, the next step in the process is to separate the sediment using a centrifuge or diatomaceous earth filtration. Both processes remove large particles and microorganisms from the filtrate, to avoid blocking the surface of the filter sheets in downstream sheet filtration. The desired level of clarity after using the centrifuge/ diatomaceous earth filtration is 2 NTU. During filtration using depth filter sheets (e.g. BECO KD and BECO Steril 40), the cider is usually at 0 C. The low filtration temperature favors the separation of unstable phenol and protein components, and thus stabilizes the cider. The ideal flux rate during cold filtration is around 200 250 l/m 2 /h. This enables the whole adsorptive Using current production processes combined with biotechnological products, both large-scale and small-scale producers can meet the highest requirements and can handle fluctuations in apple quality without losing the regional touch and typicity of their cider. There is a clear emphasis on preserving the natural apple aroma, in order to offer the consumer a typical and traditional cider. Purity and product safety are the primary considerations here. These are followed by an effective juice yield from the apple mash through the controlled breakdown of pectins by enzymes, controlled alcoholic fermentation with active dry yeast and yeast nutrients without the formation of undesirable flavors such as volatile acids as well as the harmonization of acidity through targeted MF using malolactic bacteria, and finally cold filtration with depth filter sheets to stabilize the cider. What is therefore important is a complete solution that represents expertise in products and product applications. References: AICV, The European Cider & Fruit Wine Association, European Cider Trends 2014, 2014 Zhao H., Zhou F., Dziugan P., Yao Y., Zhang J., LV Z., Zhang B., Development of organic acids and volatile compounds in cider during malolatic fermentation, 2008, Czech Journal Food Science, Vol. 32, No. 1: 69 76 Alberti A., Braga C M., Jaster H., Nogueira A., Dissolved oxygen content in apple must: technological implications in cider processing, 2014, Journal Institute of Brewing & Distilling, 120: 65 70, wileyonlinelibrary.com DOI 10.1002/jib.113 Riekstina-Dolge R., Kruma Z., Karklina D., Seglina D., Composition of aroma compounds in fermented apple juice: effect of apple variety, fermentation temperature and inoculated yeast concentration, 2011, Procedia Food Science, 1: 1709 1716 Burona N., Cotona M., Leg P., Implications of Lactobacillus collinoides and Brettanoymces/Dekkera anomal in phenolic off-flavour defects in cider, 2012, International Journal of Food Microbiology, 153: 159 165 Cotona M., Romanob A., Spanoc G., Occurrence of biogenic amine-forming lactic acid bacteria in wine and cider, 2010, Food Microbiology, 27:1078 1085 Jarvis B., Cider, Encyclopedia of food microbiology, Volume 1, 2014: 437 443 Panzym is a registered trademark of Novozymes A/S. Viniflora is a registered trade mark of Chr. Hansen. SIHA, SIHA SpeedFerm and BECO are registered trademarks of Eaton. Author: Dr Ilona Schneider Team Leader Product Management, Beverage Treatment and R&D Eaton Technologies GmbH www.eaton.de 142 July / August 2015