Food Biochemistry and Food Processing (2 edition)

BLBS102-c35 BLBS102-Simpson March 21, 2012 14:9 Trim: 276mm X 219mm Printer Name: Yet to Come

678 Part 6: Health/Functional Foods

Time (h)

0 5 10 15 20 25

pH

4.5

5.0

5.5

6.0

6.5

7.0

Milk : Bifidobacterium longum R0175

Milk: Lactobacillus helveticus R0052

Soy: Bifidobacterium longum R0175

Soy: Lactobacillus helveticus R0052

Figure 35.1.Acidification of milk or soy beverages adjusted at

identical protein and fat levels by two probiotic cultures. (Redrawn

from Champagne et al. 2010.)

be linked to their growth rates on lactose (Table 35.1). It was

examined, if this extended to soy fermentation as well. However,

it was observed that acidification rates in a soy beverage by two

probiotic cultures were much higher than in milk (Fig. 35.1) even

though their growth rates on soy carbohydrates were lower that

on lactose (Table 35.1). These data show that enzyme activity on

carbohydrate is not always the limiting factor on growth rates and

fermentative activity. As was the case in milk, amino acids in soy

are mainly found in the proteins. Therefore, proteolytic activities

are crucial to attain high biomass levels in a soy substrate. A

link was indeed established between the ability of bifidobacteria

to synthesize galactosidases as well as proteinases and their

multiplication in a soy substrate (Donkor et al. 2007).

With respect to soy, another enzymatic system is also of inter-

est: hexanal and pentanal assimilation. These compounds con-

tribute to the “beany” flavor of soy (Desai et al. 2002, Blagden

and Gilliland 2005). For some consumers, this is an undesirable

trait. Both lactobacilli (Blagden and Gilliland 2005) and bifi-

dobacteria (Desai et al. 2002) have been shown to reduce the

level of these metabolites in fermented soy products.

Prebiotics and Other Foods

Prebiotics are nondigestible food ingredients that beneficially

affect the host by selectively stimulating the growth and/or ac-

tivity of one or a limited number of bacteria in the GI system,

and thereby confer health benefits to the host (Roberfroid 2007).

This definition overlaps with the definition of dietary fiber, with

the exception of its selectivity for certain bacterial species and

a wider range of health effects. Peptides, proteins, and lipids

contain prebiotics characteristics, but some carbohydrates have

received the most attention, including lactulose, inulin, and a

range of oligosaccharides that supply a source of fermentable

carbohydrate for the beneficial bacteria in the colon (Prado et al.

2008).

The nutritional composition of pulses such as complex car-

bohydrates (Table 35.3), protein, vitamins, and minerals as well

as antioxidants, and only very small amounts of unsaturated

Table 35.3.Average of Carbohydrate Content in Different Canadian Pulses and Their Digestibility in Human Body

Mean of Carbohydrates Content in Pulses (g/100 g dry matter)

Sucrose Raffinose Stachyose Verbascose Oligosaccharides

Digestibility in human body +− − − −

Chickpea (desi) 2.03 0.54 1.64 NDa 2.18

Chickpea (kabuli) 3.84 0.61 2.20 NDa 2.81

Green lentil 2.01 0.43 2.09 0.56 3.07

Red lentil 1.80 0.42 1.94 0.52 2.87

Field pea 2.8 0.7 2.7 1.0 4.4

Navy bean 3.2 0.5 4.0 NDa 4.6

Black turtle bean 3.93 0.57 3.50 0.07 4.14

Cranberry bean 4.14 0.23 3.13 0.21 3.58

Dutch brown bean 2.85 0.34 2.97 0.17 3.47

Dark red kidney bean 3.45 0.26 3.80 0.14 4.20

Great Northern bean 5.14 0.54 3.42 0.02 3.98

Light red kidney bean 4.69 0.26 3.44 0.16 3.85

Pink bean 4.54 0.31 3.65 0.02 4.02

Pinto bean 4.40 0.37 3.65 0.04 4.07

Small red bean 4.74 0.45 3.48 0.09 4.02

White kidney bean 3.67 0.22 3.53 0.18 3.93

aNot defined.

From Wang and Daun, 2004.