Fruit fermentation product range

A large spectrum of berries and fruits are used in the production of fruit juice products. The range of products is substantially extended by an additional (fermentation) process to produce alcohol, and transform the fruit into wine. Enzymes, some of them proteolytic, are used to increase the yield of fruit juice during extraction, and to produce the required degree of clarity for the final product. 

Many fruits and vegetables are processed through lactic acid fermentation for the production of a wide range of traditional fermented products in various worldwide regions, mainly in the Mediterranean area. The manufacturing protocols for some traditional fermented vegetables are described below. Due to the wide literature describing the lactic acid fermentation of table olives, they are not considered in this chapter. 

Esters also constitute a group of important flavour compounds. They are the main aroma components found in fruits (apples, pears,. ..). For example, bananas contain 12-18 ppm acetates. The price of the pure flavour compounds, when isolated from fruit, can range between 10,000 and 100,000 US /kg In the past, research has been carried out by our group about the microbial production of fruity esters by the yeast Hansenula mrakii and the fungus Geotrichum penicillatum [10]. A fermentation was developed whereby fusel oil was continuously converted into a mixture of 3-methylbutyl acetate (isoamyl acetate) and 2-methylbutyl acetate, the character impact compounds of banana flavour. 

Bakery Products. Sorbates are used in and/or on yeast-raised and chemically leavened bakery products. The internal use of sorbates in yeast-raised products at one-fourth the amount of calcium—sodium propionate that is normally added provides a shelf fife equal to that of propionate without adversely affecting the yeast fermentation. Sorbates added at one-tenth the propionate level reduce the mix time by 30% (126). This internal treatment combined with an external spray of potassium sorbate can provide the same or an increased shelf fife of pan breads, hambuiger and hot-dog buns, Enghsh muffins, brown-and-serve rolls, and tortillas. The total sorbate useful in or on these baked goods ranges from 0.03 wt % for pan breads to 0.5 wt % for tortillas 0.2—0.3 wt % sorbic acid protects chemically leavened yellow and chocolate cakes (127). Fruit-pie fillings and icings can be protected with 0.03—0.1 wt % sorbates. 

Solubility. Solubility is an important functional property per se, i.e. in fluid products, and is essential for other functionalities since insoluble proteins can not perform useful functions in foods. The caseins are, by definition, insoluble at their isoelectric points, i.e. in the pH range c. 3.5-5.S the insolubility range becomes wider with increasing temperature. Insolubility in the region of the isoelectric point is clearly advantageous in the production of acid casein and is exploited in the production of two major families of dairy products, i.e. fermented milks and fresh cheeses. However, such insolubility precludes the use of casein in acid liquid foods, e.g. protein-enriched fruit juices or carbonated beverages. Acid-soluble casein can be prepared by limited proteolysis or by interaction with certain forms of pectin. 

Microbes use enzymes as catalysts to make the desired or beneficial reaction take place, and typically under mild conditions. Brewing of beer and fermentation of fruit and vegetable mass high in starches to produce consumable ethanol are the oldest and most familiar instances of using microbial action to fulfill a desired end. But now much more has been demonstrated, ranging from the production of essential human hormones to the synthesis of specialty chemicals. 

It is my belief that the availability of on-line computer control has enabled the food process plant designer to achieve this end. Countless plants dealing with the blending of wine or fruit juices, the fermentation and maturation of beer, the continuous production of ice cream and the aseptic processing of a wide range of food products, now rely upon process logic as written in computer programs. 

Citrate is present in milk, fruit, and vegetables. It can be co-metabolized with sugars by citrateutilizing LAB. Citrate utilization results in an excess of pyruvate, which is thus converted to diacetyl (2,3-butanedione), acetoin (2-hydroxy-3-butanone), and 2,3-butanediol to equilibrate the redox balance of cellular metabolism (Collins 1972 Bartowsky and Henschke 2004). Some LAB can also synthesize 2,3-pentanedione from pyruvate and threonine (Ott et al. 2000). Diacetyl and 2,3-pentanedione are associated with a buttery aroma, which positively contributes to the flavor of a range of fermented dairy products such as butter (MalUa et al. 2008), yogurt (Routray and Mishra 2011), and cheese (Curioni and Bosset 2002). Diacetyl also contributes to wine style, while it is responsible for flavor defects in beer. Diacetyl is widely produced by LAB, including species of the Lactococcus, Streptococcus, Leuconostoc, Lactobacillus, Pediococcus, and Oenococcus genera. 

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