Sep 14, 2010: Daring Cooks' Apple Butter

The September 2010 Daring Cooks’ challenge was hosted by John of Eat4Fun. John chose to challenge The Daring Cooks to learn about food preservation, mainly in the form of canning and freezing. He challenged everyone to make a recipe and preserve it. John’s source for food preservation information was from The National Center for Home Food Preservation.

Hello Daring Cooks! I have the honor of hosting this month's challenge. I’m John from Eat4Fun.

[Yes, that's me! I'm hosting this month's Daring Cooks' Challenge! Woo Hoo!

I wanted to provide a challenge that was unique, provide information that people could use beyond the challenge and a challenge that was vegetarian/vegan friendly. Also, I wanted to use ingredients that were readily available.

I gave two options canning or freezing. Canning requires that you buy jars and lids while, a less expensive option, is freezing where you can find good containers for under $5 for a multi-pack.]

When Lis and Ivonne asked if I would host a challenge, I jumped at the chance. Being a person who enjoys experimenting around with different cooking techniques and learning about new topics, I racked my brain trying to figure out what to present. Chinese cooking? Grilling? Barbecuing? Roasting? Tofu making?

I finally decided on a topic that takes advantage of the time of year where, in the Northern Hemisphere, our gardens and local farms should be harvesting an abundance of fresh fruits and vegetables.

For this month's challenge, I hope to whet your appetite on the vast topic of Food Preservation. Food preservation is a broad subject covering canning, freezing, drying, pickling, fermentation and jam making, but for this challenge the focus will be on freezing and home canning. The main recipe for our challenge will be apple butter. However, a couple additional recipes are provided for a little added variety.

Apple butter is essentially an apple sauce that’s been cooked down with spices to form a thick spread. No butter is used in making apple butter. “Butter” just refers to the spreadable consistency of the final product. Talking with a family friend, she mentioned that apple butter was a way of using the scraps, skins and cores, after making apple sauce. The spices were added to flavor the scraps. Nowadays, recipes use the whole apple, which is what we’ll use for this challenge.

Disclaimer: Since I am an engineering geek, I present a lot of technical information on food preservation. The apple butter is actually a very simple recipe, so please do not be discouraged by the information and jargon used in this write-up.

Why Preserve Foods?
There are many reasons – save the harvest from our garden for later in the year, control the ingredients that go into our food, nostalgia (memories of our parents or grandparents), make gifts, satisfaction of making it yourself… etc. For me, it’s curiosity, controlling what I eat and just the satisfaction of making it myself.

Why foods go bad?
Before we start preserving foods, we need to know why foods spoil.

The two main culprits are
1) The obvious culprit is bacteria, molds and yeast/fungi. I call them “bad bugs.” There are “good bugs” that help with fermentation (yogurt, beer, wine, sourdough breads and pickles), but the bad bugs rots foods, gives foods an off taste and can make us sick.
2) The other culprit is enzymes. Enzymes are molecules that occur naturally in food which encourage chemical changes, some of which are desirable - help ripen fruit by converting starch to sugar, soften fruits or vegetables, or reduce acidity level. Some changes are not desirable, browning when an apple is cut, or the fruit becomes overripe where the flesh becomes soft and mushy.

The other supporting culprits are oxygen and unintentional moisture loss. Fortunately, when we eliminate microorganisms, the rest of the culprits are taken care off at the same time.

Good bugs and bad bugs keep growing and growing?
Bacteria, molds and yeast are living organisms that are present at all times – in the air, on surfaces, and on our food. In order for organisms to survive, they need food, water, oxygen (although some microorganisms can survive without oxygen) and a comfy environment.

A better way to remember food, water, oxygen and comfy place to live is by remembering “FATTOM” or “FAT TOM”. No, FATTOM is not the guitar riff to “Smoke on the Water” [F-A-T, T-T, O-M; F-A-Tee-Tee-O-M]. FAT TOM represents the six conditions microorganisms need to grow/multiply.

FAT TOM is Food, Acidity, Temperature, Time, Oxygen and Moisture.
* Food - Microorganisms, like people, need nutrients. Unfortunately, that means microorganism eat what we eat. Some microorganisms can get by with sugar while other need protein. The foods of concern from a food safety standpoint are low acid, protein rich foods, such as, meat, dairy and egg containing foods.

* Acidity – Acidity is a value between 0 to 14 (known as pH) where values less than 7 are acidic and values above 7 are alkaline. For example, water is generally neutral at pH = 7 while vinegar is acidic with a pH between 2.4 and 3.4. Most foods we eat have a neutral to acidic pH where foods with values 4.6 or higher are considered low acid foods.

* Temperature – Temperatures between 40F (4.4C) to 140F (60C) is considered the Temperature Danger Zone (TDZ) where microorganisms can grow. The optimal temperature for growth is typically between 70F (21C) to 100F (38C). Note: In the USA, the FDA is lowering the higher temperature from 140F to 135F (57C).


- Food Safety Tip: Hot foods should stay hot, above 140F (60C). Cold foods should stay cold, below 40F (4.4 C)

* Time – Given the right conditions and temperatures 40F to 140F, microorganisms start growing. Given enough time, the population will grow rapidly to levels that can make us sick.

- Food Safety Tip: Two hour rule and the Four hour rule.
Foods kept at room temperature (in the TDZ) should be refrigerated before two hours. Foods are to be thrown out after 4 hours in the TDZ. For hot days, for example a 90F (32C) day, the time is cut in half.

- Food Safety Tip: Also, cooling foods in the refrigerator, foods should be cooled within two hours (from 140F (60C) to 70F (21C)). Of course, faster is better. For example, a pot of chili beans can be cooled quickly by pouring into a baking dish where the chili beans are spread out into a thin layer.

* Oxygen – Most microorganisms need air. There are a couple bad bugs that don’t need air to grow where Clostridium botulinum (Botulism), being the most notorious bad bug that prefers a no oxygen environment.

* Moisture – Pure water is the key to life while salt water is less desirable.

How does knowing FAT TOM help us preserve food?
Food preservation works by changing the condition of our food to discourage bad bug growth. Food is what we are trying to save and Time is beyond our control. The remaining factors we can change are Acidity, Temperature, Oxygen and Moisture.

Brief summary of how each food preservation method works.
Preservation Method	Acid	Temperature	Oxygen	Moisture
Freezing		Storing foods at 0F (-17.8C) or lower	Airtight packaging
Boiling Water Canner (high acid foods)/Pressure Canner (low acid )	Some foods can be acidified using vinegar or lemon juice	Heats foods to kill bad bugs and neutralize enzymes	Jars form a vacuum seal – creates a low oxygen environment
Pickling and Fermentation	Food is acidified by using vinegar or natural bacteria creating lactic acid			Brines (salted water) and sugars reduce fresh water
Drying			Airtight packaging	Removes up to 90% of the moisture
Jam and Jellies	Vinegar or Lemon juice, Fruits naturally acidic	Cooking, canning or Freezing	Canning will create a vacuum seal	Sugar reduces water available

For this daring challenge, we will be focusing on Freezing and Boiling Water Canning.

Freezing:
Freezing refers to storing foods in airtight containers at 0ºF (-17.8ºC) or lower. Freezing does not kill bad bugs. The cold temperature causes the microorganisms to go into hibernation/suspended animation.

Freezing is the easiest food preservation method, especially with modern freezers.
The main pointers for freezing:
1) Freeze foods quickly. Quickly freezing creates smaller ice crystals. Water is a funny substance where water expands when frozen. This means larger ice crystals can puncture cell walls (such as whole berries) so when defrosted you end up with a mushy mass.
2) Try not to freeze too much at once. Typical advice 2 to 3 lbs (1 kg) per cubic foot (28 L) of freezer space.
3) Containers should be airtight and leak proof.
4) Minimize air and gaps in the packaging. This reduces the chance for freezer burn – drying.
5) Label and date the package. Frozen foods tend to look the same over time, especially when a layer of ice has formed.
6) Vegetables can be blanched to deactivate enzymes. Blanching is quick cooking in boiling water for a few minutes and cooled rapidly in ice water.
7) For initial freezing using pliable freezer bags, freeze on a smooth, flat surface to prevent the bag from molding itself to the rack.

Boiling Water Canning:
Boiling water canning sterilizes the food using the temperature of boiling water. The jars form a vacuum seal which creates a low air/oxygen environment.

Important!
The temperature that water boils varies with altitude. At sea level, water boils at 212ºF (100ºC) while at 5,000 ft (1524 m) water boils at 203ºF (95ºC). What this means is canning (processing) times increase with altitude. Fortunately, we don’t need to do the math. Canning recipes include processing times for different altitudes

Boiling water canning is appropriate for high acid foods (foods with pH values lower than 4.6). Typically, fruits are high acid foods while vegetables are low acid. There are a few fruits that are on the border (pH 4.6), such as, tomatoes. However, some borderline pH foods can be acidified by adding vinegar or lemon juice. In home canning, lemon juice (and lime juice) refer to bottled concentrate, unless the recipe calls for fresh. Also, vinegar refers to vinegar with 5% acidity. The percentage strength can be found on the label.

In the USA, home canning uses Mason jars, a thick-walled jar. The lid is a two piece assembly – the lid with a reddish sealing compound and a metal band/ring.

Jars should be inspected before each use – looking for cracks and chips. Washed with detergent dish soap and dried. To reduce thermal shock (hot food cracking a cold jar), the jars should be kept hot. Clean jars can be kept hot by submerging in the boiling water canner or in a dishwasher. Also, a warm oven can be used.

For processing (canning) times less than 10 minutes, the jars need to be sterilized for 10 minutes in boiling water. For altitudes higher than a 1,000 ft (305 meters), an additional minute is added for each 1,000 ft (305 meters) above sea level.


Figure illustrates the jars and lids used in the USA.

The basic steps for using a boiling water canning.
1. Check your jars for chips, cracks and nicks. Wash and preheat your jars.
2. Fill you canner half full with water. Preheat water to 140ºF (60ºC) for raw packing foods or 180ºF (82ºC) for hot packing foods.
3. Fill jars with food prepared according to the recipe, remove bubbles and adjust headspace.
4. Load jars into the canner. It’s important to keep the jars level.
5. Add more hot water, as needed, so the jars are submerged by at least 1 inch (2.54 cm) of water.
6. Cover the canner with the lid and turn the heat to high.
7. Set timer when the water comes to a vigorous boil. You can lower the heat, but the boil must be maintained.
8. When the time is up, turn off the heat and remove the lid. Wait 5 more minutes.
9. Remove jars making sure the jars are level and set on a towel. Allow to cool to room temperature, undisturbed for 12 to 24 hours.

Terminology
Headspace – is the gap between the top of the container to the level of the liquid or food.
For freezing, headspace is important to ensure there is room in the container for the expanding food. For canning, headspace ensures that a proper vacuum seal will form without the food spilling out of the jars while canning.




Raw Pack (canning) – foods are placed in jars raw and, typically, a flavored liquid is added to the jars before processing. Advantages: Food is not cooked twice. Retains shape better. Disadvantages: Uses more jars. Foods may float due to trapped air.

Hot Pack (canning) – foods are cooked before jarring. Advantages: Foods are cooked down so more can be packed into a jar. Less air in food. Disadvantages: Original shape is lost.

Recipe Source:
Reduced Sugar Apple Butter from The National Center for Home Food Preservation – [http://www.uga.edu/nchfp/how/can_02/apple_butter_reduced.html]

Oven Roasted Tomatoes from Susy Hymas, Master Food Preserver

Bruschetta in a Jar from the Bernardin Canning website.
[http://www.bernardin.ca/pages/recipe_page/51.php?pid=435]

Blog-checking lines:

Posting Date: September 14, 2010

Note:
For making apple butter, I do not have a food mill. The first time I made this recipe, I used apples with the stem and blossom end removed. I pressed the soft cooked apples through a mesh strainer. The resulting apple butter yield was barely 3 cups. Therefore, I recommend using peeled and cored apples to yield 5 to 6 cups of apple butter.

Mandatory:
I want all you daring cooks to try canning or freezing one of the recipes presented in the challenge. If you’re leery about making the full recipe, feel free to half a recipe. How much your freeze or can is up to you. My goal is to have you all become comfortable with food preservation.

The apple butter can be frozen or canned while the oven roasted tomatoes are better suited for freezing. The bruschetta is best canned due to the raw tomatoes. Raw tomatoes tend to become soft when frozen and defrosted.

Variations allowed: If you are familiar with home canning and would like to show us your favorite up to date recipe, please feel free to show us your recipe. Remember to reference the source for your recipe.

Preparation time:
- Apple Butter
Preparing Apples: 10 Minutes (if you leave the skin on)
20 Minutes if you peel and core apples
Cooking: 20-30 Minutes to soften apples for mashing + 2 hours to make Apple Butter.
Boiling Water Canner: 40 Minutes

- Roasted Tomatoes
Preparation: 10 Minutes
Cooking: 1 Hour


- Bruschetta in a Jar
Preparation: 15-30 minutes
Canning: 30 Minutes

Equipment required:
Apple Butter
• Knife
• Measuring Cup
• Measuring Spoons
• 8 Quart (about 7½ litres) Sauce Pan or Pot
• Potato Masher
• Storage Container/Containers to hold 5 to 6 cups
Optional:
o Scale
o Vegetable Peeler
o Food Mill
o Freezer Bags/Containers
o Boiling Water Canner
- Pot with Lid
- Rack
- Jars with lids and bands
- Bubble Remover (can use small spatula or plastic knife)
- Wide Mouth Funnel

Roasted Tomatoes
• Knife
• Roasting Pan
• Mixing Bowl

Bruschetta in a Jar
• Knife
• Measuring cups and spoons
• Cutting Board
• Sauce Pan
• Boiling Water Canner + Accessories
• Scale (Optional)

Recipes: Reduced Sugar Apple Butter Recipe
My preference is to use sweet apples (Golden Delicious) so the need for sugar is reduced. However, tart apples (Granny Smith) can be used. It’s a matter of personal preference.

Recipe: Reduced Sugar Apple Butter
Ingredient	U.S.	Metric	Count	Special Instructions
Apples	4lbs*	1.8 kg	12 Apples	Cut into eights, stem and blossome end removed
Apple Cider	1 Cup	240 ml		Optional: Water or Juice
Sucralose/Splenda	1/2 Cup	120 ml		Optional: Honey, Agave or Sugar - to taste
Cinnamon, Ground	1 Tbl	15 ml
Allspice, Ground	1/2 tsp	3 ml
Cloves, Ground	1/4 tsp	2 ml

Note: * If you used peeled and cored apples. I recommend buying 5 lbs (2.26 kg) of apples.


Gala and Golden Delicious Apples

Directions:
1. Wash apples well and remove stems. Cut apples into quarters or eighths and remove cores.

Note: I ended up peeling the apple at this step.


2. Combine unpeeled apples and cider in 8-quart (about 7 ½ litre) saucepan. Cook slowly and stir occasionally to prevent sticking. Cook until apples are very soft (falling apart).


3. Position a food mill or strainer securely over a large bowl. Press cooked apples with cider through the food mill or strainer to make a pulp. Be sure to collect all the pulp that comes through the food mill or strainer; for example, scrape any pulp clinging under the food mill into the bowl.

Note: Since the apples were peeled, I just mashed in the pot.


4. Combine pulp with Sucralose and spices in an 8-quart (about 7 ½ litre) saucepan. Simmer over low heat, stirring frequently.

Note: A stick blender was used to mix the spices and creates a smoother apple butter. Also, when cooking down the apples, you want to leave the lid ajar or use a splatter screen. This will allow for evaporation. Another trick is to support the lid by laying two wooden spoons across the top of the pot.


5. To test for doneness, spoon a small quantity onto a clean plate; when the butter mounds on the plate without liquid separating around the edge of the butter, it is ready for processing. Another way to test for doneness is to remove a spoonful of the cooked butter on a spoon and hold it away from steam for 2 minutes. It is done if the butter remains mounded on the spoon.

Note: It may be difficult to see, but the sample on the left is the apples sauce from step 3. The apple sauce left a liquid ring while the apple butter did not.


6. Pour contents into desired storage container or multiple containers. I stored my apple butter in 1-cup (250ml) plastic containers with screw on tops. Refrigerate up to 2 weeks, freeze up to a year, and home canning is good for a year.

* The Finished Apple Butter:
Apple Butter is often used as a spread. However, apple butter can also be used as a condiment (pork chops or in marinades) or as an ingredient to an apple quick bread.




* Freezing:
I used a freezer bag where I expelled as much air as possible and minimized the gaps in the bag. Freezer bags work well for storage since they can lay flatter in the freezer than containers.


With a container, you need to ensure you have “headspace”. Headspace is the gap between the food (or liquid level) and the top of the container. Typical, headspace when freezing foods is 1/2 “ (1.27 cm) for straight sided containers. As mentioned previously, water expands when freezing. The headspace allows room for expansion.


Thawing: The best method (Food Safety) is to thaw in the refrigerator for a day.
Cold water, 70ºF (21ºC) or lower, can be used for as quicker way to defrost. The frozen food is submerged under running water. An alternative to running water is to change the water every 30 minutes. If you need an even faster method to defrost and you plan to cook the food immediately, the microwave is another method (of last resort).

* Boiling Water Canning:
For our challenge, apples are high acid foods. Golden delicious apples have an approximate pH of 3.6. Boiling Water Canning is an appropriate method of preserving apple butter.

Apple Butter processing information:
Headspace when canning apple butter is 1/4 “ (0.64 cm)

Processing Time:
15 minutes for altitude of 0 ft (0 m) to 1,000 ft (305 m)
20 minutes for altitude of 1,001 ft (305.1 m) to 6,000 ft (1828.8 m)
25 minutes altitudes above 6,000 ft (1828.8 m)


For boiling water canning, you need a pot that is high enough to cover the jars with at least 1” (2.5 cm) of water. Also, a rack, to prevent thermal shock, is used to keep the jars off the bottom of the pot. Any type of rack will work – a tea towel, a trivet, tying together unused bands… etc. I improvised a rack by tying metal bands to a bamboo sushi mat.


Also, for my pot, I used a large tamale steamer.


Jars are filled using a wide mouth funnel. A plastic bubble remover is run along the sides of the jar, in an up and down motion, to remove air pockets.
The top and side of the jar are wiped down with a damp paper towel.


Headspace is measured to ¼" (6.5mm).


Lids are placed in a pan of hot water (180ºF or 82ºC) to soften the sealing compound.


The lid is seated, centered on the jar and the band is screwed on.
The purpose of the band is to hold the lid down, but not too tightly. Air from the jar needs to escape into the boiling water.

I generally screw down the bands (using two fingers) until resistance stops the band. After which, I give a slight additional 1/4" (6.5mm) twist.


The jars are lowered into the hot water canner. Water temperature is about 180ºF (82.2ºC).
The water level is checked to ensure there is at least 1” (2.54 cm) of water above the jars.
Next, pot is covered and heat turned to high.
When the water comes to a boil, the timer is started (15 minutes). The heat can be lowered as long as the water remains at a boil.

After the 15 minutes are up, the whole canner is removed off the burner (I have an electric stove) and uncovered. Jars are left in the canner for 5 more minutes.


After 5 minutes, the jars are lifted out level.
The temptation is to tilt the jars to drain the water off the top of the lids. Do NOT do that! You don’t want to contents of the jar to running under the seal.


Jars are placed on a dish towel to minimize thermal shock and allowed to cool for 12 to 24 hours.
While the jars are cooling, you may hear a ping or a pop from the lid as it seals. That ping is a good sound. For these three jars, they all pinged within a minute.


After 24 hours, test the seal. The lid should be bowed down (concave), when you press down the lid should not move or pop up. Also, try lifting the jar by the lid only. The lid should stay on if properly sealed. The final thing is to look at the lid to see if there are any cracks or debris caught between the jar and the lid.


Jar Lift:


Storing – Once the integrity of the lids have been checked, it’s best to store the jars in a cool, dark space. The rings are removed. The rings have done their job of holding down the lids in the boiling water canner and are not needed for storage.


Remember to check the lid before you open a jar.
If the lid has become unsealed during storage or the lid is bulging, throw it out.
If the food has mold, become oddly discolored or has an off odor, throw it out.

The canned apple butter can easily store on a shelf for one year.

Additional Recipes:
Tomatoes are a popular home garden plant. There are seasons when we hit the jackpot with tomatoes. Here are a couple recipes that will help preserve the tomatoes for later in the year.

Recipe: Oven Roasted Tomatoes (for Freezing)
Ingredient	U.S.	Metric	Count	Special Instructions
Tomatoes	1lbs	455 g	10 to 12	Cut in half or thirds. Core if needed
Fresh Basil			3 leaves	Chiffonade (Cut into thin strips)
Fresh Garlic			2 Cloves	Minced
Olive Oil	1 Tbl	15 ml
Salt			1 or 2 pinches
Cloves, Ground	1/4 tsp	2 ml

Coring a tomato


Bake 325 F for an hour or slightly browed.

The finished tomatoes can be stored as-cut, chopped or pureed to make a sauce or tomato paste.


Additional Recipe: Bruschetta in a Jar
Recipe Source: Bernardin Canning Website - http://www.bernardin.ca/pages/recipe_page/51.php?pid=435

Recipe: Bruschetta in a Jar
Ingredient	U.S.	Metric	Count	Special Instructions
Plum/Roma Tomatoes *	3 1/2 lbs	1.6 Kg	20 Medium	Wash, seed and chop
Fresh Garlic			5 Cloves	Minced
Dry White Wine	1 Cup	250 ml
White Wine Vinegar	1 Cup	250 ml
Balsamic Vinegar	2 Tbl	30 ml
Sugar, Granulated	2 Tbl	30 ml
Dried Basil	2 Tbl	30 ml
Dried Oregano	2 Tbl	30 ml

* Note: Although other tomato varieties may be used, firm plum tomatoes yield the best results. If using round garden-variety tomatoes, seed tomatoes and drain in colander for 30 minutes then chop.

Headspace: 1/2 “ (1.27 cm)

Processing Time:
20 minutes for altitude of 0 ft (0 m) to 1,000 ft (305 m)
25 minutes for altitude of 1,001 ft (305.1 m) to 3,000 ft (915 m)
30 minutes for altitude of 3,001 ft (916 m) to 6,000 ft (1,830 m)
35 minutes altitudes above 6,000 ft (1,831 m) to 8,000 ft (2,440 m)

1) Place 7 clean half-pint (250 ml) mason jars on a rack in a boiling water canner; cover jars with water and heat to a simmer (180°F/82°C). Set screw bands aside. Heat lids in hot water, not boiling (180°F/82°C). Keep jars and sealing discs hot until ready to use.

2) Wash, seed and chop tomatoes into 1/2 inch (1cm) pieces; measure 9 cups (2250 ml), set aside.

3) Combine garlic, white wine, wine vinegar, balsamic vinegar, water, sugar, basil and oregano in a deep stainless steel saucepan. Bring to a full boil; reduce heat. Stirring occasionally, boil gently, covered, 5 minutes. Remove from heat.

4) Pack tomatoes into a hot jar to within 3/4 inch (2 cm) of top rim. Add hot liquid to cover tomatoes to within 1/2 inch (1 cm) of top rim (headspace). Using nonmetallic utensil, remove air bubbles and adjust headspace, if required, by adding more tomatoes and hot liquid. Wipe jar rim removing any food residue. Centre hot sealing disc on clean jar rim. Screw band down until resistance is met, then increase to fingertip tight. Return filled jar to rack in canner. Repeat for remaining tomatoes and hot liquid.




5) When canner is filled, ensure that all jars are covered by at least one inch (2.5 cm) of water. Cover canner and bring water to full rolling boil before starting to count processing time. At altitudes up to 1000 ft (305 m), process –boil filled jars – 20 minutes.

6) When processing time is complete, remove canner lid, wait 5 minutes, then remove jars without tilting and place them upright on a protected work surface. Cool upright, undisturbed 24 hours; DO NOT RETIGHTEN screw bands.

7) After cooling check jar seals. Sealed discs curve downward and do not move when pressed. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars, as desired. Label and store jars in a cool, dark place. For best quality, use home canned foods within one year.

Serving Suggestions:
With boiling water canning, very little oil is used since the oils can weaken the seals on the jar.
For the Bruschetta, olive oil and fresh herbs can be added before serving on top of toasted bread or as a condiment to a dish.



Challenge Summary:
For this challenge, I wanted to pique your interest on the topic of food preservation. The subject may seem daunting, due to my long-winded and geeky explanations, however you will find the process of canning and freezing to be very simple.

I do recommend using tested, research based recipes for boiling water canning. There are many research based websites that offer a lot of information and tested recipes which make the whole food preservation process pretty straightforward.



Additional Information:
USDA Guide to Home Canning: http://www.uga.edu/nchfp/publications/publications_usda.html

For food preservation information, canning guides, recipes and how-to for various foods, I highly recommend The National Center for Home Food Preservation website. http://www.uga.edu/nchfp/index.html

Another website is Ball/Kerr/Bernadin (All owned by Jarden): http://www.homecanning.com/
I used the Canadian version of the website for recipes in metric units.

Approximate pH of Foods: http://foodscience.caes.uga.edu/extension/documents/FDAapproximatepHoffoodslacf-phs.pdf

This pdf contains a larger list of references (WSU Extension C1117E): https://cru84.cahe.wsu.edu/ListItems.aspx?Keyword=C1117E