Juices enzyme treatment

Table V. Effect of Enzyme Treatment on Naringin Content and Bit-terness Perception in Grapefruit Juice.(79) ...

Juice solids have a critical effect not only on wine quality (discussed under juice clarification) but also on yeast activity. A juice that is too clean, from excessive pectic enzyme treatment, filtration, or centrifuging, may have difficulty completing fermentation. Groat and Ough (24) and others have reported that juice solids levels below 0.1 to 0.5 percent resulted in slower fermentations. Levels of 0.5-2.5 percent solids are used commonly in the North Coast. 

Acid hydrolysates were added to a low aroma intensity white wine (ie the base wine), and the aroma properties of these samples were assessed by sensory descriptive analysis. In addition, the glycoside isolates from the Australian vineyards were subjected to glycoside hydrolase enzyme treatment, and duo-trio difference tests were performed on these hydrolysates added to a base wine. The volatile composition of each of the hydrolysates was investigated by GC/MS, and relationships between the two sets of data were determined. Finally, the glycoside concentration of each of the juices and skin extracts was determined by the glycosyl-glucose assay. 

In order to produce clear juice the cloudy product is treated with pectolytic enzymes to degrade the pectic substances which are responsible for the cloud stability of the cloudy juice. The treatment time depends on the activity of the enzymes and the temperature respectively. Several years ago the industry had no enzymes which were able to work in very acid juice environments (e.g. lemon juice). However, in the meantime new types were developed which are capable of treating acid juices satisfactorily. Some fruit juices contain substances which cannot be removed with pectolytic enzymes and which require other specific enzymatic products to eliminate turbidity, e.g. starch in apple juice requires a suitable amylase. 

Glycosldases in winemaking. Enzyme treatment of juices or wines to increase the concentrations of volatile monoterpene flavorants could, if successful, provide considerable benefit to winemaking. 

Enzyme treatment of pulp of soft fruit, red grapes, citrus and apples, for better release of juice and colour pigments. 

Figure 3 Flow diagram of fruit juice manufacture. Arrows indicate eventual enzyme treatments ...

Table IV. Effect of enzyme treatment and storage on apple juice yields...

The purpose of this study was to examine the efficacy of a process to produce clear juice from a model concentrate, apricot, utilizing enzyme treatment and microfiltration. Specific goals were to determine (a) if effective flux rates could be achieved, and (b) if clarified juice of acceptable quality could be produced. 

Figure 1. Changes in juice and pulp as a result of enzyme treatment of apple pulp.

Enzymic treatment of less-well-defined protein systems results in an alteration of the functional properties of the proteins. One of the primary functional properties is solubility since a protein generally must be in solution before it can exert many of its other functionalities. Unfortunately, many protein concentrates are either naturally insoluble or rendered insoluble at pH values in the neutral range by processing treatments which denature the proteins. Many protein concentrates tend to be insoluble at acidic pH values around 5(6) and require alkaline conditions for solubilization. Supplementation of an acidic soft drink or citrus juice with protein, for example, would require solubilization of the protein at acidic pH values. Consequently, proteolytic enzymes have been employed to solubilize proteins from various sources and thus alter their solubilities through proteolysis and modify their other functional properties. 

Bayindirli et al (2006) studied the effectiveness of treatment on pectinesterase activity in orange juice, comparing the application of high hydrostatic pressure with a mild heat treatment. The residual pectinesterase activity in the orange juice after treatment at 450 MPa and 50°C for 30 minutes was determined as approximately 7 1.6%. This compares with 12 0.2% after a treatment of 40°C and 450 MPa for 60 minutes. The inactivation was irreversible and the enzyme was not reactivated when stored at 4 and 25 °C for 1 week. 

Ingallinera, B., Barbagallo, R.N., Spagna, G., Pahneri, R., and Todaro, A. 2005. Effects of thermal treatments on pectinesterase activity determined in blood orange juices. Enzyme Microb. Technol. 

The freshly-pressed juice of the apple is naturally more or less cloudy as well as somewhat thick or syrupy in body, and it quickly oxidizes both in color and flavor. These attributes characterize cider in the older tradition. Enzyme-treatment and filtration... 

Enzymic treatment with cucumber juice. The O consumed in the enzymic reaction was detected Automated enzyme packed-bed system (ascorbate oxidase)... 

Use of ultrafiltration (UF) membranes is becoming increasingly popular for clarification of apple juice. AH particulate matter and cloud is removed, but enzymes pass through the membrane as part of the clarified juice. Thus pasteurization before UF treatment to inactivate enzymes prevents haze formation from enzymatic activity. Retention of flavor volatiles is lower than that using a rack-and-frame press, but higher than that using rotary vacuum precoat-filtration (21). 

Pectic enzymes are inactivated by pasteurization. Citms juices require higher temperatures for enzyme deactivation than for pasteurization. Heat treatment at 85—94°C for 30 s inactivates pectic enzymes (9) and is more than adequate for pasteurization. 

KROGDAHL A, HOLM H (1981) Soybean proteinase inhibitors and human proteolytic enzymes selective inactivation of inhibitors by treatment with human gastric juice. /M/fr. Ill 2045-51. 

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