UPMSP Class 12 Food & Fruit Preservation - Code 202 cheat sheet

Food spoilage is any change making food unfit or unacceptable: microbial, chemical (oxidation, browning), physical (moisture loss, freezer burn) or enzymatic.

Microbial spoilage agents: bacteria (mostly pH above 4.6, high water activity), yeasts (sugars, acidic foods) and moulds (low water activity, aerobically).

Water activity (aw) is the ratio of vapour pressure of food to that of pure water; most spoilage bacteria need aw above 0.90, xerophilic moulds grow near 0.65.

Intrinsic factors controlling spoilage: pH, aw, nutrient content, oxidation-reduction potential, natural antimicrobials and competing microflora.

Extrinsic factors: temperature, relative humidity, gases (O2, CO2) and light; these determine which organisms dominate.

pH 4.6 is the dividing line between low-acid foods (need pressure canning) and acid/high-acid foods (boiling water processing is often adequate).

Enzymatic browning (polyphenol oxidase) needs oxygen and is controlled by blanching, sulfites, citric acid or oxygen exclusion.

Nutrient losses during storage: vitamin C and thiamine are the most heat- and oxygen-sensitive; fat-soluble vitamins are lost mainly by oxidation.

Preservation principles: asepsis, removal of microorganisms (filtration, centrifugation), inhibition of growth, and destruction of organisms.

Hurdle technology combines several sub-lethal preservative factors (aw, pH, heat, preservative, packaging) so no single factor must be severe.

Preservation methods grouped as physical (heat, cold, drying, irradiation, high pressure), chemical (preservatives, acids, salt, sugar) and biological (fermentation).

Blanching inactivates enzymes and removes tissue gases before freezing or drying; it is not a sterilization step.

Chilling range is roughly 0–7 °C; freezing range is −18 °C or below for long-term storage.

Commercial sterility means freedom from viable organisms capable of growing under normal storage, not absolute sterility.

Irradiation doses are expressed in kGy; low doses (sprout inhibition, insect disinfestation) are below 1 kGy.

Preservation choice depends on product pH, aw, heat sensitivity, intended shelf life and packaging system.

Fruits and vegetables are living tissue after harvest; respiration rate and ethylene production determine perishability class.

Climacteric fruits (banana, mango, tomato, apple) ripen after harvest with an ethylene peak; non-climacteric (citrus, grape, pineapple) do not.

Blanching uses hot water or steam, typically 90–100 °C for 1–5 minutes, followed by rapid cooling.

Pectin and pectinase control jam and jelly set; a good set needs acid (pH about 3.0–3.5), sugar (about 65°Brix) and pectin together.

Pectin gels form at roughly 60–65% soluble solids; below about 55% the product is a low-sugar gel needing added pectin or calcium.

Fruit juice processing: extraction, clarification (enzymes, fining), filtration, pasteurization and filling; pulp juices are not clarified.

Fruit beverages are classified by fruit content: juice (100%), nectar (about 25–50% fruit), squash and cordial (diluted before drinking).

Tomato products are standardized by total soluble solids: paste about 25–30°Brix, ketchup about 25–28% solids with sugar, salt and vinegar.

Heat processes: pasteurization (below 100 °C, targets vegetative pathogens), boiling (100 °C), and sterilization (above 100 °C in a pressure retort).

Low-acid canned foods (pH above 4.6) require a 12-D process for Clostridium botulinum: 121 °C for at least 3 minutes in the coldest point.

D value is the time at a given temperature to reduce a population by 90%; z value is the temperature change giving a tenfold change in D.

F0 (sterilizing value) is equivalent minutes at 121 °C with z = 10 °C; a minimum F0 of 3 minutes is used for low-acid foods.

In-container sterilization uses a retort or pressure cooker; the retort must be vented to remove air before pressure builds.

Exhausting (removing air from the headspace) and adequate headspace are needed to form a vacuum on cooling and prevent seam strain.

Canned food spoilage types: flat sour (no gas, Bacillus), thermophilic anaerobic spoilage, putrefactive (Clostridium), and leaker spoilage from seam defects.

Bottling of acidic products (juices, sauces) uses hot fill and hold or pasteurization; glass requires gradual heating and cooling to avoid thermal shock.

Chilling slows microbial growth and respiration but does not stop them; typical storage is 0–5 °C with high relative humidity.

Freezing lowers aw and stops microbial growth, but enzymes and some microorganisms survive and resume activity on thawing.

Freezing rate controls ice crystal size: fast freezing gives many small intracellular crystals and better texture; slow freezing gives large extracellular crystals.

Freezer burn is surface dehydration from sublimation; prevented by tight packaging and stable temperature.

Cold storage disorders: chilling injury in tropical fruits (banana, mango) below about 10–13 °C; apple scald and internal browning.

Controlled atmosphere storage lowers O2 (about 2–3%) and raises CO2 to slow respiration; ultra-low oxygen is below 1.5% O2.

Freezing point depression depends on solute concentration; most fruits freeze between −1 and −3 °C.

Thawing should be slow and controlled (refrigerator) to reduce drip loss and microbial growth.

Drying removes water to lower aw below about 0.60, the level at which most spoilage organisms cannot grow.

Drying rate curve: constant-rate period (surface evaporation controls) then falling-rate period (internal diffusion controls).

Sun drying is cheap but slow and weather-dependent; cabinet, tunnel, drum, spray and freeze drying are controlled methods.

Spray drying suits liquids (milk, juice powder) with very short contact time; freeze drying (lyophilization) sublimates ice and best preserves structure.

Osmotic dehydration uses concentrated sugar or salt solution to draw water out before further drying.

Case hardening occurs when the surface dries too fast and seals, trapping moisture inside.

Blanching or sulfiting before drying controls browning and vitamin loss; sulfites are restricted in many markets.

Rehydration ratio and water activity (measured by hygrometer or aw meter) are quality checks for dried products.

Class I preservatives (natural): salt, sugar, vinegar, honey, spices, edible oils; Class II are chemical additives such as benzoates and sorbates.

Sodium benzoate is effective in acidic foods (pH below 4.5); potassium sorbate works over a wider pH range and inhibits yeasts and moulds.

Sulfur dioxide and sulfites inhibit browning and moulds; permitted limits apply and labels must declare sulfites.

Salt preserves by lowering aw; a 10–15% brine inhibits most spoilage bacteria but halotolerant organisms survive.

Sugar preserves by lowering aw; jams at about 65% soluble solids resist spoilage, though osmophilic yeasts may grow.

Nitrites in cured meat inhibit Clostridium botulinum and fix colour; nitrosamine formation is the main safety concern.

Fermentation: lactic acid bacteria (Lactobacillus) convert sugars to lactic acid, lowering pH; used in sauerkraut, pickles, yoghurt.

Alcoholic fermentation by yeasts (Saccharomyces cerevisiae) produces ethanol and CO2; acetic acid bacteria then make vinegar from ethanol.

Packaging functions: containment, protection, preservation, convenience and communication; barrier properties matter most for oxygen and moisture.

Materials: glass (inert, heavy), metal cans (tinplate, aluminium), plastic films (PE, PP, PET, EVOH), paper and laminates.

Modified atmosphere packaging changes the gas mix (typically low O2, elevated CO2); vacuum packaging removes air to suppress aerobes.

FSSAI is the Indian food regulator; the Food Safety and Standards Act 2006 consolidated earlier food laws and sets standards and labelling.

Label essentials: product name, ingredients in descending order, net quantity, nutrition information, FSSAI licence number, batch, date marking and veg/non-veg mark.

HACCP is a preventive system with seven principles: hazard analysis, CCPs, critical limits, monitoring, corrective action, verification and record keeping.

Good Manufacturing Practice and Good Hygiene Practice are prerequisite programmes supporting HACCP.

Quality tests: pH, titratable acidity, °Brix, aw, moisture, total plate count, coliform count, yeast and mould count, and sensory evaluation.

Business plan components: product, market analysis, production plan, cost of project, means of finance, profitability and break-even.

Fixed cost plus variable cost gives total cost; break-even quantity = fixed cost ÷ (selling price per unit − variable cost per unit).

Licensing route for a small food unit: FSSAI registration or state licence depending on turnover, plus GST, Udyam and local trade licence.

Food processing schemes (PMFME, PMKSY) offer capital subsidy and credit-linked support; verify current terms before quoting figures.

Marketing mix: product, price, place, promotion; for foods, shelf life and distribution temperature constrain place and price.

Sensory evaluation by a trained panel uses 9-point hedonic scale for liking and triangle or duo-trio tests for difference detection.

A student project should state aim, raw material, process flow, observations in a table, calculations and conclusion.

Costing a product requires accounting for raw material, packaging, labour, utilities, wastage and overheads per unit output.