Processing technology of almond fermented yoghurt

(1) Product features

Bitter almond, the dried seed of almond, was used as the main raw material to produce plant protein fermented milk beverage by lactic acid bacteria fermentation. Lactic acid fermentation improves the special aroma of bitter almonds and makes them more acceptable to consumers. Bitter almond is rich in a variety of unsaturated fatty acids, protein content of about 24%, rich in vitamins, iron and other trace elements, with high nutritional value and health care function.

(2) main raw and auxiliary materials

Bitter almond, white granulated sugar, skim milk powder, acid-resistant sodium carboxymethyl cellulose, Lactobacillus bulgaricus and Streptococcus thermophilus.

(3) technological process

Almond → peeling → soaking detoxified → pulping → filtering → almond pulp → mixed blending → homogenized → sterilization → cooling → inoculation → fermentation → finished product

(4) description of operation points

(1) preparation of starter

① weighed 0.1g dry powder (mixed powder of Lactobacillus bulgaricus and Streptococcus thermophilus 1 ∶ 1) dissolved in 5ml 0.9% peptone solution.

② absorbs 0.5ml of the dissolved dry powder albumen solution into the bevel medium. Preparation of slant subculture medium: 100g skimmed milk powder was dissolved in 1000 ml distilled water and sterilized for 20 minutes; 25g 30g Agar and 2.5g yeast paste were added to 300ml distilled water, boiled and dissolved, 121ml ℃ sterilized for 20 minutes; the two liquids were mixed under sterile conditions while hot to make a slant (the amount of solution was 15ml).

③ put a burned candle in a dry dish, put it on the bevel where the bacteria were inoculated, and could not leak air. It was cultured in a 37 ℃ incubator for 18 hours for 24 hours.

④ picked the bacteria from the slant into the milk test tube medium and cultured them at 37 ℃ for 24 hours.

Preparation of test-tube culture medium for milk: 120g skim milk powder was dissolved in 1000 ml of distilled water, 20ml was placed in the test tube, kept at 95 ℃ for 20 minutes, and sterilized intermittently in water bath for 3 times.

⑤ strain domestication: 4% bacteria were inoculated from milk test tube medium to almond juice test tube medium and cultured at 41 ℃ for 8 hours for 12 hours.

A. Almond juice test-tube medium preparation: almond pulping (180mesh sifted, plus 10 times water) 20ml mixed with 80ml milk (milk powder: water = 1:7), 20ml was placed in the test tube, kept at 95 ℃ for 20 minutes, and sterilized 3 times in the water bath gap.

B. expanded culture in triangular flask: 4% bacteria were taken from the above culture medium to be cultured in triangular flask and cultured in 41 ℃ for 8 hours.

C. Preparation of triangular flask medium: 600ml almond juice (ibid.) mixed with 400ml milk (ibid.), poured into triangular beaker, kept at 95 ℃ for 20 minutes, intermittent sterilization in water bath for 3 times. After expanded culture, it is an almond milk starter that can be used directly.

(2) preparation of almond fermented milk beverage

① almond peeling: boil the almonds with 2% sodium hydroxide solution for 3-4 minutes, then peel with a peeling machine, and manually select the almonds that meet the requirements.

② immersion detoxification: soak in clean water for 20 hours for 24 hours, and change the water for 2 times for 3 times.

③ mixed blending: according to the almond (wet weight) and milk powder ratio of 100 ∶ 10, sucrose dosage of 8%, sodium carboxymethyl cellulose ∶ alginate propylene glycol = 2 ∶ 1, the total dosage of both is 0.2% 0.3%. First, the milk powder, white granulated sugar and stabilizer were mixed and dissolved, and when the almond pulp was heated to 70 ℃, it was added to the slurry, stirred evenly and kept for 10 minutes. After blending, the final slurry solids were 8% and 12%.

④ homogenization: while hot homogenization, the pressure is 35 ~ 40 MPA.

⑤ sterilization: 95 ℃, 20 minutes water bath sterilization.

⑥ cooling: cooling to 40-45 ℃.

⑦ inoculation: add activated and expanded culture starter, according to 4% of the amount of access.

⑧ fermentation: anoxic fermentation in (41 ±1) ℃ greenhouse (or incubator). The general acidity reached 50 ~ 70 °T (titration acidity) and was taken out at pH ≤ 4.2.

⑨ after ripening: store in 4 ℃ cold storage for 12 hours.