**6. Antioxidant potential of fermented soybean**

Administration of high single dose of MK‐7 (2000 mg/kg) did not impart any toxic effect in animal modeling study in both genders. Moreover, prolonged treatment of MK‐7 is considered also safe for human consumption due to its non‐toxic effect on biochemical, hematological,

Recently, Indian researcher Puri et al. identified a *B. subtilis* strain (*Bacillus subtilis MTCC 2756*) for the biosynthesis of menaquinone‐7 for commercial purposes [32]. They found that addition of Tween 80 in fermentation medium significantly boost the MK‐7 yield. Likewise, for the production of MK‐7, groundnut meal is also used as a substrate owing to its protein and oil quality with strong minerals and vitamins profile using *Flavobacterium* sp. *SP‐L‐01* [33].

The vitamin K2 was quite stable at room temperature for a period of up to 3 years. However, its concentration in final product was little affected by storage timed. Therefore, it is recom‐ mended that the menaquinone‐7 rich product should be stored not more than 15°C tempera‐

Fermented soybean is demonstrated higher amount of protein than raw soybean. The higher content of protein in fermented soybean might be elevated due to the microbial synthesis of single cell protein or rearrangements of molecules or enzymes followed by mortification of other moieties [19]. Premarani et al. explicated the impact of fermentation on the proximate composition of hawaijar [34]. They inferred that natural fermented soybean had 62.1% moisture, 26.02% soluble protein 24.36% crude fat, 8.2% crude fiber, 1.42% ash, and 3.8% free amino acids content nonetheless, inoculation with bacteria increases these parameters. However, hawaijar prepared from different soybean varieties showed non‐momentous differences in lipid, fatty acid, and amino acid contents [35]. The nutritional profile of some

**Food Moisture Crude protein Crude fat Crude fiber Ash Carbohydrate References**

**Natto fresh weight basis** 62.72 13.19 7.61 1.17 1.37 13.89 [2] **Fermented soybean** 62.1 26.02 24.68 8.2 1.42 [34] **B. natto Itobiki** 59–61 36–42 19–23 – 4.38–4.97 31–34 [37] **B. Natto NRRL B‐3393** 61 39–44 25–27 ‐ 4.72–4.86 25–29 [37]

7.2 44.0 21.8 4.2 4.7 29.7 [79]

6.8 45.1 23.0 4.8 4.5 27.4 [79]

ture in a dry, cool, and dark place away from humidity, high heat, and sunlight.

**5. Nutritional profile of fermented soybeans products**

urinary, and histopathological parameters [31].

40 Vitamin K2 - Vital for Health and Wellbeing

**4. Stability of menaquinones**

fermented soybean was listed in **Table 2**.

**Table 2.** Nutritional profile of menaquinones rich fermented soybean (%).

**Kinema (traditional)**

**Kinema (pure culture)**

**dry basis**

**dry basis**

Fermented soybean had higher amount of total phenolic, antioxidant capacities, and flavonoid contents in thua nao produce by black soybeans by pure culture of *B. subtilis TN51* compared with yellow soybeans and cooked non‐fermented soybeans. Fermented black soybean and yellow soybean with *B. subtilis* TN51 exhibited higher amount of total phenolics 27.05 and 35.88 mgGAE/g extract than that of non‐fermented products. Whereas total flavonoids contents of fermented black and yellow soybean were 3.50 and 1.38 mg catechin eq/g metha‐ nolic extract. However, contents of total phenolics and flavonoids were significant less in non‐ fermented black and yellow cooked soybeans. Likewise, 2,2‐diphenylpicrylhydrazyl (DPPH)‐ antiradical activity (IC50, mg/mL), and lipid peroxidation inhibition potential were higher in fermented black and yellow soybean compared with non‐fermented cooked soybean [22].

Total phenol content of kinema was 144% higher than the raw soybean. Moreover, kinema has better free radical scavenger ability and metal chelating power and improved reducing power than that of non‐fermented soybean. Therefore, it is suggested that kinema may has potential used as designer foods to alleviate oxidative stress [43]. Likewise, *B. subtilis* fermentation inclines to improve total polyphenolic and anthocyanins content about 10 and 250% during natto preparation from black soybeans, respectively. Moreover, DPPH radical scavenging activity has positive association with fermentation time and concentration of black soybean [19].

Fermentation increases about 58% content of phytosterol in kinema [43]. Later, Moktan et al. [44] reported that the kinema had 144%, 44%, 147%, and 92% higher total phenolics content, antioxidant activity, DPPH scavenging activity, and Fe2+‐chelating activity, respectively, compared to non‐fermented cooked soybean. Similarly, better total phenolic contents and DPPH activity were observed in Bacillus fermented soybean than that of soaked or cooked soybean [19].

intramuscular fat and tenderness of meat. Contrary, Fujiwara et al. reported that poultry birds rely on natto did not improve the menaquinones content of meat [49]. Previously, Elder et al. [50] quantified the MK‐4 in beef, chicken, fish, and liver of calf available in retail outlets or fast food restaurants of various cities of USA and reported that MK‐4 was present in chicken in substantial amount ranged from 6.3 to 22.1 μg/100 g as compared to other tested animal meat

Vitamin K2 Rich Food Products http://dx.doi.org/10.5772/63902 43

**Meat Type Country MK‐4 MK‐6 MK‐7 Reference** Chicken Breast meat Netherlands 8.9 – – [13] Chicken Leg meat Netherlands 8.5 – – [13] Chicken Thigh raw Japan ND ‐ 27 ± 15 [12] Chicken Leg and thigh ng/g Japan 600 ND ND [12] Chicken Fresh ng/g Japan 89.9 ND ND [12] Beef Chuck, raw Japan 0.6 ‐ 15 [12]

Beef Fresh raw ground beef USA 4.9 – – [50] Beef Fresh raw ground beef (medium fat) USA 8.1 – – [50] Beef Fresh raw ground beef (high fat) USA 7.4 – – [50] Bovine beef Fresh beef (ng/g) Japan 34.3 0.3 0.3 [12] Cattle (Jersey) M. Biceps Femoris Norway 4.85 0.004 0.006 [48]

Cattle (Norwegian Reg) M. Biceps Femoris Norway 3.02 0.006 0.082 [48]

Beef Minced meat Netherlands 6.7 – – [13] Beef Product Salami Netherlands 9.0 – – [13] Pork Thigh, raw Japan ND 6 ± 2 [12] Pork Fresh pork meat (ng/g) Japan 9.4 0.3 0.3 [12] Pork Pork meat chop (ng/g) Japan 31 ND 1.2 [12] Horse Fresh house meat ng/g Japan 2.0 0.2 2.3 [12] Luncheon Meat Netherlands 7.7 – – [13] Hare Leg meat Netherlands 0.1 – – [13] Deer Back meat Netherlands 0.7 – – [13] Goose Leg meat Netherlands 31 – – [13] Goose Liver paste Netherlands 369 – – [13] Duck Breast meat Netherlands 3.6 – – [13]

**Table 3.** Menaquinones contents of meat of various fresh meat (μg/100 g).

Beef raw Netherlands 1.1 – – [13]

*M. psoas major* Norway 2.46 – – [48] M. longissimus dorsi Norway 3.39 – – [48]

*M. psoas major* Norway 1.82 – – [48] M. longissimus dorsi Norway 2.43 – – [48]

and meat products (**Table 3**).

During fermentation process of soybean, peptides are released by the hydrolysis of soybean proteins. Specific bioactive peptides such as glycinin and β‐conglycinin are synthesized through the hydrolysis of soybean proteins. These bioactive peptides may act as regulatory compounds and have potential to minimize the physiological dysfunctions such anti‐diabetic and anticancer activities [45].

Generally, fermented products are still widely synthesized by traditional methods. Conse‐ quently, it was recommended to develop standard operating producers and adhere with the good manufacturing practice (GMP) for individuals directly involved in its production for ensuring its safety [43].
