Progress 10/01/08 to 09/30/11
Outputs
OUTPUTS: In the first year of this project, we had identified apple and grape varieties suitable for the production of high quality vinegars and fermented and acetified all samples for preliminary quality appreciation. Low acetification rates of 0.1-0.31 % acetic acid per day were reached in static processes. Cellulose formation was observed in some acetifications, particularly those from cider apples. We investigated different method for the quantification of the substrate, ethanol. Considered were ebouillometry, titration with chromate, enzymatic tests, as well as spectrophotometric determination by near infrared spectroscopy. While NIR is used to determine ethanol in the exhaust gas from vinegar plants in industry, the utilization of bench-top NIR meters for the measurement of residual ethanol in liquid vinegar without any pre-treatment had not been investigated yet. We have been able to validate a new method that applies a bench-top NIR spectrophotometer for the determination of ethanol in vinegars. The method work well within the alcohol range 0.05-10% v/v at up to 10% (w/v) acetic acid. The availability of the method has proven crucial for the first submers (i.e. liquid) acetifications, where acetification rates of >1% (w/v) per day have been reached and the prediction of the acetification end-point is essential to prevent over-oxidation. In this final year, we have produced vinegars from the above mentioned vinegars by submers technique and applied the NIR technology developed to follow the substrate ethanol levels to prevent over-oxidation of the vinegars. The submers vinegar production by sparging was significantly faster and led to reduced cellulose film formations. In spite of the latter, acetic acid yields were lower since active aeration led to stripping of ethanol and acetic acid with the exhaust. Another aspect, which may be industrially relevant was the smell caused by aerations. Upon carrying out the sensory analysis of submers and surface vinegars, it was found that those produced by the slow, traditional surface method were more intense in flavor. However, this was predominantly judged significant for aromatic dessert varieties. For aromatically bland apple varieties it was deemed advantageous from a sensory point of view to blend back non-fermented must to the ciders to enhance typicity. This was not needed for cider apples, which preserved typical aromatics throughout the process (Brown Snout, Chisel Jersey, Tremletts Bitter). PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The major outcomes of this project have been: - Elaboration of a protocol for the successful double (alcoholi and vinegar) fermentation of apple musts - Study of the suitability, the advantages and inconveniences of rapid and slow vinegar making technologies allowing potential producers to make well informed choices - Providing data about the suitability of various apple varieties for the production of vinegars - Validation of a NIR and FT-NIR method for the rapid determination of acetic acid and ethanol in wines and vinegars.
Publications
- No publications reported this period
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: We have successfully acetified two grape and 11 apple varieties using a static surface process and demonstrated that all varieties could be successfully fermented and acetified using the proposed protocol. Preliminary data about the aromatic suitability of apple and grape varieties was obtained. Grape vinegars and those elaborated from cider apples presented a higher concentration of impact odorants and thus appear more suitable for high quality, monovarietal or blended vinegars. Dessert apple vinegars may serve as base vinegars for blends. Process observations, i.e. the formation of significant cellulose films in only some cultures, revealed differences with regards to product characteristics that will be of significance in commercial processes and need to be further studied. In the past reporting period, we have validated an improved ethanol detection method allowing to streamline the production process in small operations. Several submers techniques have been applied successfully for the following upscaling. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: The direct target audience of this project is the New York State wine industry. However, project results are of interest to the global wine industry as evidenced by invited conference presentations on this topics in Chile, Argentina, Spain and France. The final objective of this project is a reduction in wine acetaldehyde levels, which would lead to reduced utilization of the wine preservative SO2, which can cause adverse effects in sensitive consumers. Accordingly, wine consumers can be regarded as the eventual target audience, as well. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In the first year of this project, we have identified apple and grape varieties suitable for the production of high quality vinegars and fermented and acetified all samples for preliminary quality appreciation. We sought input from experts in viticulture and pomology and selected 2 grape and 11 apple varieties for processing based on the recommendations received. These were Niagara and Concord as well as Cortland, Goldrush, Macintosh, Jonagold, Golden Delicious, Ida Red, Mutsu, Brown Snout, Chisel Jersey, Tremletts Bitter and Dabinett for grape and apple varieties, respectively. The grape varieties are non-vinifera cultivars, which are suffering from structural weaknesses of the market and low prices compared to V. vinifera varieties. With regards to the apple varieties, both dessert apples and cider apples, were chosen. Apples were stored in order to achieve starch degradation as suggested. Grapes were used directly. All fruit was destemmed (grapes) or ground (apples) and pressed in order to obtain musts that were clarified before fermentation with a standard yeast strain (DV10, 25 g/hl). Suspended solid levels varied from 9 (Niagara) to 18.6 Brix (Brown Snout). Where applicable, sugar was added to the musts to achieve at least 12.7 Brix in order to reach final acetic acid levels of 6% (v/v). 60 g/hL of diammonium phosphate and 25 g/hl of a yeast nutrient were added to every batch to support alcoholic fermentation. After alcoholic fermentation, wines/ciders were racked once, and kept in carboys with minimal head space and without further additions. The pH values of wines/ciders thus obtained ranged between 3.37 (Niagara) and 4.31 (Brown Snout). Acetification was induced by inoculation of a commercial Acetobacter starter to a water, wine/cider, white vinegar mixture and acetifications were carried out at 30 deg C in static aerobic flask cultures. Acetification rates of 0.1-0.31 % acetic acid per day were reached in this process and all acetifications went to completion. Cellulose formation was observed in some acetifications, particularly those from cider apples. The aromatic evaluation of vinegars corresponded well with wine/cider characteristics and cider apples and Niagara/Concord provided the most aromatic vinegars. Vinegar from cider apples presented slight precipitations, but all final vinegars were clear and bright. In the past reporting period, we have validated a new method to monitor the acetification progress, which is necessary for the greatly increased acetification rates observed in submers processes (>1-2 % acetic acid per day). The method relies on the measurement of residual ethanol using a near infrared analyzer.
Publications
- No publications reported this period
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: We have successfully acetified two grape and 11 apple varieties using a static surface process and demonstrated that all varieties could be successfully fermented and acetified using the proposed protocol. Preliminary data about the aromatic suitability of apple and grape varieties was obtained. Grape vinegars and those elaborated from cider apples presented a higher concentration of impact odorants and thus appear more suitable for high quality, monovarietal or blended vinegars. Dessert apple vinegars may serve as base vinegars for blends. Process observations, i.e. the formation of significant cellulose films in only some cultures, revealed differences with regards to product characteristics that will be of significance in commercial processes and need to be further studied. The remaining project milestones, i.e. acetification up-scaling, consideration of different acetification techniques, as well as product stability, will be critical to present a comprehensive production protocol. PARTICIPANTS: The selection of grape and apple varieties was based on recommendations by Cornell University experts in viticulture (Dr. Tim Martinson) and pomolgy (Dr. Ian Merwin). TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In the first year of this project, we have identified apple and grape varieties suitable for the production of high quality vinegars and fermented and acetified all samples for preliminary quality appreciation. We sought input from experts in viticulture and pomology and selected 2 grape and 11 apple varieties for processing based on the recommendations received. These were Niagara and Concord as well as Cortland, Goldrush, Macintosh, Jonagold, Golden Delicious, Ida Red, Mutsu, Brown Snout, Chisel Jersey, Tremletts Bitter and Dabinett for grape and apple varieties, respectively. The grape varieties are non-vinifera cultivars, which are suffering from structural weaknesses of the market and low prices compared to V. vinifera varieties. With regards to the apple varieties, both dessert apples and cider apples, were chosen. Apples were stored in order to achieve starch degradation as suggested. Grapes were used directly. All fruit was destemmed (grapes) or ground (apples) and pressed in order to obtain musts that were clarified before fermentation with a standard yeast strain (DV10, 25 g/hl). Suspended solid levels varied from 9 (Niagara) to 18.6 Brix (Brown Snout). Where applicable, sugar was added to the musts to achieve at least 12.7 Brix in order to reach final acetic acid levels of 6% (v/v). 60 g/hL of diammonium phosphate and 25 g/hl of a yeast nutrient were added to every batch to support alcoholic fermentation. After alcoholic fermentation, wines/ciders were racked once, and kept in carboys with minimal head space and without further additions. The pH values of wines/ciders tuhs obtained ranged between 3.37 (Niagara) and 4.31 (Brown Snout). Acetification was induced by inoculation of a commercial Acetobacter starter to a water, wine/cider, white vinegar mixture and acetifications were carried out at 30 deg C in static aerobic flask cultures. Acetification rates of 0.1-0.31 % acetic acid per day were reached in this process and all acetifications went to completion. Cellulose formation was observed in some acetifications, particularly those from cider apples. The aromatic evaluation of vinegars corresponded well with wine/cider characteristics and cider apples and Niagara/Concord provided the most aromatic vinegars. Vinegar from cider apples presented slight precipitations, but all final vinegars were clear and bright.
Publications
- Mira de Orduna, R. (2008) From wine to Vinegar. Cornell Research in Viticulture and Enology Conference, Ithaca, New York
|
|